Ali Hamza Ahmad al Bahlul v. United States , 840 F.3d 757 ( 2016 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued December 1, 2015             Decided October 20, 2016
    No. 11-1324
    ALI HAMZA AHMAD SULIMAN AL BAHLUL,
    PETITIONER
    v.
    UNITED STATES OF AMERICA,
    RESPONDENT
    On Petition for Rehearing En Banc
    Michel Paradis, Counsel, Office of the Chief Defense
    Counsel, argued the cause for petitioner. With him on the
    briefs were Mary R. McCormick and Todd E. Pierce, Counsel.
    David Weissbrodt and William J. Aceves were on the
    brief for amici curiae International Law Scholars in support
    of petitioner.
    J. Douglas Richards was on the brief for amicus curiae
    National Institute of Military Justice in support of petitioner.
    Robert Barton was on the brief for amicus curiae
    Professor David Glazier in support of petitioner.
    Ian Heath Gershengorn, Principal Deputy Solicitor
    General, U.S. Department of Justice, argued the cause for
    2
    respondent. On the brief were Steven M. Dunne, Chief,
    Appellate Unit, and John F. De Pue and Joseph Palmer,
    Attorneys.
    James A. Schoettler Jr. was on the brief for amici curiae
    Former Government Officials, Former Military Lawyers, and
    Scholars of National Security Law in support of respondent.
    Richard A. Samp was on the brief for amici curiae John
    D. Altenburg, Maj. Gen., U.S. Army (Ret)., et al. in support
    of respondent.
    Before: GARLAND, Chief Judge, and HENDERSON,
    ROGERS, TATEL, BROWN, GRIFFITH, KAVANAUGH,
    SRINIVASAN, MILLETT, PILLARD, and WILKINS, Circuit
    Judges.
    Opinion for the Court filed PER CURIAM.
    Concurring opinion filed by Circuit Judge HENDERSON.
    Concurring opinion filed by Circuit Judge KAVANAUGH,
    with whom Circuit Judges BROWN and GRIFFITH join.
    Concurring opinion filed by Circuit Judge MILLETT.
    Concurring opinion filed by Circuit Judge WILKINS.
    Joint Dissenting opinion filed by Circuit Judges ROGERS,
    TATEL, and PILLARD.
    
    Chief Judge Garland was a member of the en banc court at the
    time the case was argued but did not participate in this opinion.
    
    Circuit Judge Srinivasan did not participate in this matter.
    3
    PER CURIAM: Bahlul is a member of al Qaeda who
    assisted Osama bin Laden in planning the September 11,
    2001, attacks on the United States. Bahlul was convicted by a
    U.S. military commission of the offense of conspiracy to
    commit war crimes, among other offenses. The U.S. Court of
    Military Commission Review affirmed Bahlul’s conviction.
    In a prior en banc decision, we recounted the facts and
    considered Bahlul’s Ex Post Facto Clause objection to the
    conspiracy conviction. Applying plain error review, we
    concluded that the Ex Post Facto Clause did not preclude the
    conspiracy charge against Bahlul. See Al Bahlul v. United
    States, 
    767 F.3d 1
    (D.C. Cir. 2014) (en banc).
    In this en banc case, Bahlul argues that Articles I and III
    of the Constitution bar Congress from making conspiracy an
    offense triable by military commission, because conspiracy is
    not an offense under the international law of war.
    We affirm the judgment of the U.S. Court of Military
    Commission Review upholding Bahlul’s conspiracy
    conviction. Six judges – Judges Henderson, Brown, Griffith,
    Kavanaugh, Millett, and Wilkins – have voted to affirm.
    Three judges – Judges Rogers, Tatel, and Pillard – dissent.
    Of the six-judge majority, four judges (Judges
    Henderson, Brown, Griffith, and Kavanaugh) would affirm
    because they conclude that, consistent with Articles I and III
    of the Constitution, Congress may make conspiracy to
    commit war crimes an offense triable by military commission.
    They would uphold Bahlul’s conspiracy conviction on that
    basis.
    4
    Judge Millett would apply plain error review and affirm
    Bahlul’s conviction under that standard of review. She would
    not reach the question of whether Congress may make
    inchoate conspiracy an offense triable by military
    commission.
    Judge Wilkins would affirm because he concludes that
    the particular features of Bahlul’s conviction demonstrate that
    Bahlul was not convicted of an inchoate conspiracy offense.
    He further concludes that Bahlul’s conviction complies with
    the Constitution because the particular features of Bahlul’s
    conviction have sufficient roots in international law. He
    therefore would not reach the question of whether Congress
    may make inchoate conspiracy an offense triable by military
    commission.
    Judges Rogers, Tatel, and Pillard have filed a Joint
    Dissent. They conclude that Article III of the Constitution
    bars Congress from making inchoate conspiracy an offense
    triable by a law-of-war military commission.
    Bahlul has also raised First Amendment and Equal
    Protection challenges to his conviction. The Court rejects
    those challenges. See Kavanaugh Concurring Op. at 24 n.12;
    Millett Concurring Op. at 2, 44-45; Wilkins Concurring Op. at
    14. The Joint Dissent neither reaches those claims nor adopts
    the above characterization of the facts.
    ***
    We affirm the judgment of the U.S. Court of Military
    Commission Review upholding Bahlul’s conspiracy
    conviction.
    So ordered.
    KAREN LECRAFT HENDERSON, Circuit Judge, concurring:
    I join the Court’s judgment affirming Bahlul’s conspiracy
    conviction. I do so for the reasons stated in my dissent in Al
    Bahlul v. United States, 
    792 F.3d 1
    , 27-72 (D.C. Cir. 2015)
    (since vacated). I incorporate by reference thereto that
    previously published opinion as my concurrence here.
    ‎KAVANAUGH, Circuit Judge, with whom Circuit Judges
    BROWN and GRIFFITH join, concurring: Pursuant to
    congressional authorization, Presidents throughout U.S.
    history have employed military commissions to try enemy
    war criminals for conspiracy to commit war crimes. That
    history includes the two most significant U.S. military
    commission trials: the 1865 military commission trial of the
    Confederate conspirators who plotted to kill President Lincoln
    and the 1942 military commission trial of the Nazi
    conspirators who secretly entered the United States during
    World War II and planned to attack U.S. infrastructure and
    military facilities.
    In‎the‎wake‎of‎al‎Qaeda’s‎attacks‎on‎the‎United‎States‎on‎
    September 11, 2001, Congress has twice passed laws (signed
    by President Bush in 2006 and President Obama in 2009)
    expressly reaffirming that military commissions may try
    unlawful enemy combatants for conspiracy to commit war
    crimes. Pursuant to those express congressional
    authorizations, President Bush and later President Obama
    have employed military commissions to try alleged al Qaeda
    war criminals for the offense of conspiracy to commit war
    crimes. Indeed, Khalid Sheikh Mohammed, one of the
    alleged masterminds of the September 11th attacks, faces a
    conspiracy charge in his pending military commission trial.
    Several other al Qaeda members likewise have been charged
    with conspiracy before U.S. military commissions.
    Bahlul is an al Qaeda member who worked closely with
    Osama‎ bin‎ Laden‎ in‎ plotting‎ al‎ Qaeda’s‎ September‎ 11th‎
    attacks on the United States. In December 2001, Bahlul was
    captured in Pakistan. In 2008, he was tried and convicted
    before a U.S. military commission of conspiracy to commit
    war crimes.
    Citing Article I and Article III of the Constitution, Bahlul
    argues that Congress may establish military commissions only
    2
    for offenses under the international law of war. Bahlul
    further argues (and the Government concedes) that conspiracy
    is not an offense under the international law of war.
    Therefore, Bahlul contends that he may not be tried for
    conspiracy before a U.S. military commission.
    On‎its‎face,‎Bahlul’s‎argument‎is‎extraordinary.‎It‎would‎
    incorporate international law into the U.S. Constitution as a
    judicially enforceable constraint on Congress and the
    President. As a matter of U.S. constitutional law, the wartime
    decisions of Congress and the President to try unlawful
    enemy combatants before military commissions would be
    subject to the dictates of foreign nations and the international
    community, as embodied in international law.
    The Government responds that, under the Constitution,
    Congress may establish military commissions to try, at a
    minimum, (i) international law of war offenses and
    (ii) offenses that are not international law of war offenses but
    have historically been tried by U.S military commissions. As
    the Government points out, conspiracy has historically been
    tried by U.S. military commissions.
    This case therefore raises one central legal question:
    Under the U.S. Constitution, may Congress establish military
    commissions to try unlawful enemy combatants for the
    offense of conspiracy to commit war crimes, even if
    conspiracy is not an offense under the international law of
    war? The answer is yes. We know that from the text and
    original understanding of the Constitution; the structure of the
    Constitution;    landmark Supreme Court              precedent;
    longstanding congressional practice, as reflected in venerable
    3
    and contemporary federal statutes; and deeply rooted
    Executive Branch practice, from the 1800s to the present.1
    1
    The Government argues that Bahlul forfeited this claim.
    Even if that were true, the Court should review the claim de novo,
    not simply for plain error. In rare and extraordinarily important
    cases, the Court has discretion to hear even a forfeited claim de
    novo. See Plaut v. Spendthrift Farm, Inc., 
    514 U.S. 211
    , 232
    (1995). The question of whether conspiracy may constitutionally
    be tried by military commission is extraordinarily important and
    deserves‎ a‎ “definitive answer.”‎ ‎ Al Bahlul v. United States, 
    767 F.3d 1
    , 62 (D.C. Cir. 2014) (en banc) (separate opinion of Brown,
    J.). The question implicates an important part of the U.S.
    Government’s‎war‎strategy.‎‎And‎other cases in the pipeline require
    a clear answer to the question. This case unfortunately has been
    pending in this Court for more than five years. It is long past time
    for us to resolve the issue squarely and definitively.
    Judge Kavanaugh adds that he would apply de novo review for
    that reason, as well as for any of five other independent reasons.
    First, before the military judge, Bahlul objected to the military
    commission’s‎authority‎to‎try‎him‎for‎the‎charged‎offenses. Bahlul
    did not forfeit this claim. Second, even if Bahlul had not objected,
    the question of whether the Constitution requires Article III courts
    to try conspiracy offenses is a structural question of subject matter
    jurisdiction, and cannot be forfeited or waived. See Ex Parte
    Quirin, 
    317 U.S. 1
    , 25 (1942) (describing the question as one of
    “jurisdiction”).‎‎Third, in any event, Rules 905 and 907 of the Rules
    for Military Commissions require de novo judicial review of the
    question whether a charged offense may be tried by military
    commission. Fourth, even if all of those points are incorrect, the
    Government has repeatedly forfeited any forfeiture argument
    during the course of this litigation. For example, before the U.S.
    Court of Military Commission Review, the Government expressly
    acknowledged‎that‎Bahlul’s‎argument‎was‎not forfeited or waived.
    See Bahlul Appendix at 161 n.5 (quoting‎ Government’s‎
    submission: “The‎ Government‎ does‎ not‎ argue”‎ that‎ Bahlul’s‎
    argument‎“questioning‎jurisdiction”‎is “waived.”).‎‎Only‎at‎the‎11th‎
    hour has the Government belatedly claimed that Bahlul forfeited his
    4
    I
    We first address the Article I issue. Bahlul acknowledges
    that Congress possesses authority under Article I to establish
    military commissions to try war crimes. But he contends that
    military commissions may try only international law of war
    offenses.    Bahlul further argues (and the Government
    concedes) that conspiracy is not an international law of war
    offense. Therefore, Bahlul says he may not be tried by
    military commission for conspiracy.
    Contrary‎ to‎ Bahlul’s‎ argument, Article I of the
    Constitution does not impose international law as a limit on
    Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
    commission.2 That is apparent from five sources of law: the
    text and original understanding of Article I, the overall
    structure of the Constitution, landmark Supreme Court
    precedent, longstanding federal statutes, and deeply rooted
    U.S. military commission practice.
    constitutional argument. Fifth, even if Bahlul forfeited his
    argument and plain error review applied here, the Court when
    applying plain error often holds that there was no error, rather than
    merely holding that any possible error was not plain. We should do
    the same here.
    2
    To be clear, Congress may and sometimes does incorporate
    international law principles into statutes. In doing so, Congress may
    on‎occasion‎enact‎statutes‎that‎simply‎refer‎to‎“international‎law”‎in‎
    general terms. See, e.g., 22 U.S.C. §§ 5604-5605 (empowering the
    President to impose sanctions on foreign countries that use
    chemical‎or‎biological‎weapons‎“in‎violation‎of‎international‎law”).
    Likewise, the President and Senate may enter into self-executing
    treaties with foreign nations. See Medellin v. Texas, 
    552 U.S. 491
    ,
    505 n.2 (2008). Those statutes and self-executing treaties are U.S.
    law, not international law.
    5
    First, the text and original understanding of Article I
    demonstrate that international law does not impose a limit on
    Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
    commission.
    The‎ premise‎ of‎ Bahlul’s‎ Article‎ I‎ argument‎ is‎ that‎
    Congress’s‎ sole source of constitutional authority to make
    offenses triable by military commission is the Define and
    Punish Clause of Article I. That Clause grants Congress
    authority‎to‎“define‎and‎punish . . . Offences against the Law
    of‎Nations.”‎‎U.S. CONST. art. I, § 8, cl. 10. Bahlul argues that
    the‎ “law‎ of‎ nations”‎ is‎ a‎ synonym‎ for‎ international‎ law,‎ and‎
    further contends that conspiracy is not an offense under the
    international law of war. Therefore, according to Bahlul,
    Congress lacks power under Article I, Section 8 to make
    conspiracy an offense triable by military commission.
    We need not decide the scope of the Define and Punish
    Clause in this case.3 That‎is‎because‎the‎premise‎of‎Bahlul’s‎
    Article I argument is flawed. Regardless of the scope of the
    Define and Punish Clause, an issue we do not decide,
    Congress’s‎ Article‎ I‎ authority‎ to‎ establish‎ military‎
    commissions – including its authority to determine which
    crimes may be tried by military commission – does not derive
    exclusively from that Clause.
    3
    Judge Henderson and Judge Brown have previously
    concluded that the Define and Punish Clause grants Congress
    authority to make conspiracy an offense triable by military
    commission. See Al Bahlul v. United States, 
    792 F.3d 1
    , 44-55
    (D.C. Cir. 2015) (Henderson, J., dissenting); Al Bahlul v. United
    States, 
    767 F.3d 1
    , 53-62 (D.C. Cir. 2014) (en banc) (separate
    opinion of Brown, J.).
    6
    Rather, the war powers clauses in Article I, Section 8 –
    including the Declare War Clause and the Captures Clause,
    together with the Necessary and Proper Clause – supply
    Congress with ample authority to establish military
    commissions and make offenses triable by military
    commission. And the Declare War Clause and the other war
    powers clauses in Article I do not refer to international law or
    otherwise impose international law as a constraint on
    Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
    commission. Cf. Al Bahlul v. United States, 
    792 F.3d 1
    , 55-
    56 (D.C. Cir. 2015) (Henderson, J., dissenting).
    As the Supreme Court has long recognized, a
    congressional authorization of war pursuant to the Declare
    War‎ Clause‎ is‎ understood‎ “by‎ universal‎ agreement‎ and‎
    practice”‎to‎encompass‎all‎of‎the‎traditional‎incidents‎of‎war‎–
    including the power to kill, capture, and detain enemy
    combatants, and most relevant here, the power to try unlawful
    enemy combatants by military commission for war crimes.
    Hamdi v. Rumsfeld, 
    542 U.S. 507
    , 518 (2004) (binding
    opinion‎of‎O’Connor,‎J.);‎see also Hamdan v. Rumsfeld, 
    548 U.S. 557
    , 593-94 (2006); In re Yamashita, 
    327 U.S. 1
    , 11-12
    (1946).4 As Colonel William Winthrop, described by the
    Supreme‎Court‎as‎the‎“Blackstone‎of‎Military‎ Law,”‎ Reid v.
    Covert, 
    354 U.S. 1
    , 19 n.38 (1957) (plurality opinion),
    summarized‎ it:‎ “[I]n general, it is those provisions of the
    Constitution‎ which‎ empower‎ Congress‎ to‎ ‘declare‎ war’‎ and‎
    ‘raise‎armies,’‎and‎which,‎in‎authorizing‎the‎initiation‎of‎war,
    authorize the employment of all necessary and proper
    agencies for its due prosecution, from which this tribunal
    derives its original sanction. . . . The commission is simply an
    4
    On September 18, 2001, Congress authorized the use of force
    against al Qaeda and related terrorist groups. See Authorization for
    Use of Military Force, Pub. L. No. 107-40, 115 Stat. 224.
    7
    instrumentality for the more efficient execution of the war
    powers vested in Congress and the power vested in the
    President as Commander-in-chief‎ in‎ war.”‎ ‎ WILLIAM
    WINTHROP, MILITARY LAW AND PRECEDENTS 831 (rev. 2d
    ed. 1920); see also 
    Hamdan, 548 U.S. at 592
    n.21 (quoting
    Winthrop’s‎ statement‎ that‎ the‎ Declare‎ War‎ Clause,‎ among‎
    others, supplies Congress with authority to establish military
    commissions to try war crimes). So too, Justice Story
    explained‎ that‎ Congress’s‎ power‎ to‎ make‎ substantive‎ and‎
    procedural‎ rules‎ for‎ military‎ commissions‎ is‎ a‎ “natural‎
    incident to the preceding powers to make war, to raise armies,
    and‎ to‎ provide‎ and‎ maintain‎ a‎ navy.”‎ ‎ 3‎ JOSEPH STORY,
    COMMENTARIES ON THE CONSTITUTION OF THE UNITED
    STATES § 1192 (1833).5
    In short, it would be textually and historically inaccurate
    to deem the Define and Punish Clause, whatever its scope, as
    the sole source‎ of‎ Congress’s‎ authority‎ here.‎ ‎ The‎ Declare‎
    War Clause and the other war powers clauses in Article I
    authorize Congress to establish military commissions and
    make offenses triable by military commission. And those
    clauses do not refer to international law or otherwise impose
    international law as a constraint on Congress’s‎ authority‎ to‎
    make offenses triable by military commission. By their
    terms, therefore, those clauses do not confine U.S. military
    commissions to trying only international law of war offenses.
    5
    Contrary to the suggestion advanced by Bahlul and the joint
    dissent, it would be absurd to say that the war powers clauses grant
    Congress authority to establish military commissions but not to
    specify which offenses may be tried by military commission. There
    is no support in Supreme Court precedent for slicing and cabining
    Congress’s‎ war‎ powers‎ authority‎ in‎ that‎ way.‎ Moreover,‎ the‎
    longstanding historical practice in the Legislative and Executive
    Branches flatly contravenes that suggestion.
    8
    Second, the overall structure of the Constitution strongly
    reinforces the conclusion that international law does not
    impose‎ a‎ limit‎ on‎ Congress’s‎ authority‎ to‎ make‎ offenses‎
    triable by military commission.
    The Framers of the Constitution paid careful attention to
    the allocation of war powers between the national government
    and the states, and within the national government. The
    Framers assigned the national government – in particular,
    Congress and the President – the authority to make wartime
    decisions on behalf of the United States. The Framers
    assigned that power to the national government in part
    because the inability to wage war effectively had been one of
    the key weaknesses of the Articles of Confederation, and the
    Framers sought to fix that flaw.
    What matters most for present purposes is that the
    Framers certainly did not purport to afford foreign nations
    (acting through the international law of war or otherwise) any
    constitutional authority over the wartime decisions of the
    United States, such as the determination of which war crimes
    may be prosecuted by U.S. military commissions. It would be
    a historical‎ anomaly‎ to‎ conclude‎ that‎ “We‎ the‎ People‎ of‎ the‎
    United‎States”‎gave‎foreign‎or‎international‎bodies‎the‎power‎
    to constrain U.S. war-making authority in that way. Yet that
    would be the necessary consequence of the argument put
    forward by Bahlul and the joint dissent. They would
    incorporate international law into the U.S. Constitution as a
    judicially enforceable constraint on the wartime decisions of
    the Congress and the President. As a matter of U.S.
    constitutional law, Congress and the President would be
    subject to the dictates of the international community, a
    community that at any given time may be unsupportive of or
    even hostile to U.S. national security interests.
    9
    Put simply, the argument advanced by Bahlul and the
    joint‎ dissent‎ does‎ not‎ comport‎ with‎ the‎ Constitution’s‎
    structure. The Constitution does not give foreign nations
    (acting through the international law of war or otherwise) a de
    facto‎veto‎over‎Congress’s‎determination‎of‎which‎war‎crimes
    may be tried by U.S. military commissions.
    Third,‎ consistent‎ with‎ the‎ Constitution’s‎ text‎ and‎
    structure, landmark Supreme Court precedent likewise
    supports‎the‎conclusion‎that‎Congress’s‎authority‎to‎establish‎
    offenses triable by military commission is not confined by
    international law.
    The‎ Supreme‎ Court’s‎ leading‎ constitutional‎ decision‎
    regarding military commissions is Ex Parte Quirin. There,
    the Supreme Court ruled that use of military commissions to
    try war crimes was constitutionally permissible. In doing so,
    the Court emphasized that U.S. military commissions have
    long been authorized by Congress, and the Court noted in
    particular that military commissions have long tried the
    offense of spying. See Ex Parte Quirin, 
    317 U.S. 1
    , 41-42 &
    n.14 (1942). But spying was not and has never been an
    offense under the international law of war. See Government
    Br. 45 (spying not an international law of war offense); see
    also National Institute of Military Justice Amicus Br. 14-15
    n.6 (same); Curtis A. Bradley & Jack L. Goldsmith,
    Congressional Authorization and the War on Terrorism, 118
    HARV. L. REV. 2047, 2132 (2005) (same). The Court
    nonetheless relied on and approved of trying spying offenses
    by military commission.6 Quirin is admittedly a difficult
    6
    The Quirin Court’s‎discussion‎of‎spying‎was‎not‎dicta.‎‎One‎
    primary basis for the‎ Court’s‎ finding‎ a‎ military‎ commission‎
    exception to Article III was the longstanding statute that made
    spying an offense triable by military commission. See 
    Quirin, 317 U.S. at 41-42
    .‎But‎even‎if‎the‎Supreme‎Court’s‎reference‎to‎spying‎
    10
    decision‎ to‎ decipher.‎ ‎ But‎ the‎ Supreme‎ Court’s‎ reliance‎ on‎
    spying, a non-international-law-of-war offense, as an offense
    triable by military commission at least suggests – even if it
    does not conclusively show – that Congress has authority
    under Article I to make offenses triable by military
    commission even if those offenses are not war crimes under
    the international law of war.7
    The Court in Quirin did not say that military
    commissions are constitutionally permitted only for
    international law of war offenses. Nor did any later Supreme
    Court case hold that military commissions are constitutionally
    permitted only for international law of war offenses. One
    would have expected the Court at some point to say as much
    if the Court actually thought as much.
    were dicta, we as a lower court generally treat Supreme Court dicta
    as authoritative. See United States v. Dorcely, 
    454 F.3d 366
    , 375
    (D.C.‎Cir.‎2006)‎(“[C]arefully considered language of the Supreme
    Court, even if technically dictum, generally must be treated as
    authoritative.”) (internal quotation marks and citations omitted);
    Bangor Hydro-Electric Co. v. FERC, 
    78 F.3d 659
    , 662 (D.C. Cir.
    1996)‎ (“It‎ may‎ be‎ dicta, but Supreme Court dicta tends to have
    somewhat greater force – particularly when expressed so
    unequivocally.”). The Quirin Court’s‎ discussion‎ of‎ spying‎ was‎
    hardly the kind of stray comment that a lower court can or should
    cast aside.
    7
    To be sure, the Quirin Court did not expressly state that
    Congress may make non-international-law-of-war offenses triable
    by military commission. Had it explicitly done so, the question
    would be indisputably resolved and we would not be facing the
    current litigation, after all. But in considering an objection to trial
    by military commission, the Court did rely on a longstanding
    statute that made spying, a non-international-law-of-war offense,
    triable by military commission.
    11
    An amicus brief nonetheless argues that the Quirin Court
    thought that international law was a constitutional constraint
    on Congress but that the Quirin Court believed, albeit
    mistakenly, that spying was an international law of war
    offense. See National Institute of Military Justice Amicus Br.
    at 14 n.6. The joint dissent agrees. See Dissenting Op. at 25-
    26. That argument lacks foundation. To begin with, the
    Supreme Court never said anything to the effect that
    Congress’s‎ constitutional authority to make offenses triable
    by military commission is constrained by the international law
    of war. Moreover, the idea that the Court actually thought
    spying was an international law offense necessarily assumes
    that the Quirin Court – with Justices such as Harlan Fiske
    Stone, Felix Frankfurter, Robert Jackson, and Hugo Black –
    was ignorant of the content of international law. We cannot
    plausibly make such an assumption. There is no indication in
    the opinion or historical record that the Quirin Court actually
    believed that spying was an international law of war offense.
    Nor do any later Supreme Court cases suggest as much. On
    the contrary, the Quirin Court cited authorities that indicated
    that spying was not an international law of war offense. See
    
    Quirin, 317 U.S. at 30
    n.7, 31 n.8, 32, 34, 37 (citing, among
    other authorities, (i) the Hague Convention No. IV, art. 1
    (annex), 36 Stat. 2295 and (ii) the 1940 U.S. War
    Department’s‎ Rules‎ of‎ Land‎ Warfare,‎ which‎ states‎ in‎
    Paragraph‎ 203‎ that‎ spying‎ “involves‎ no‎ offense‎ against
    international‎law”).
    To be sure, the Quirin Court discussed international law
    authorities. Those international law authorities were relevant
    for, among other things, determining whether the charged
    offenses could be tried by military commission under Article
    15 of the Articles of War, which is present-day Article 21 of
    the Uniform Code of Military Justice, or 10 U.S.C. § 821.
    That statute has long used‎ the‎ broad‎ term‎ “law‎ of‎ war”‎ to‎
    12
    define the scope of offenses triable by military commission.
    The Court discussed those authorities in part because an
    offense’s‎ status‎ as‎ an‎ international‎ law‎ of‎ war‎ offense‎ is‎
    sufficient but not necessary to make an offense triable by U.S.
    military‎ commission‎ under‎ the‎ “law‎ of‎ war”‎ prong‎ of‎ 10‎
    U.S.C. § 821. See 
    Quirin, 317 U.S. at 46
    ; Al Bahlul v. United
    States, 
    767 F.3d 1
    , 65-72 (D.C. Cir. 2014) (en banc) (separate
    opinion of Kavanaugh, J.); see also 
    Hamdan, 548 U.S. at 594
    -
    95. But the Quirin Court never stated that the international
    law of war constituted a constitutional limit‎ on‎ Congress’s‎
    authority to make offenses triable by military commission.
    Fourth, when we interpret the Constitution, especially the
    provisions related to the separation of powers, the historical
    practice of the Legislative and Executive Branches matters.
    See Zivotofsky v. Kerry, 
    135 S. Ct. 2076
    , 2091, slip op. at 20
    (2015)‎ (“In‎ separation-of-powers cases this Court has often
    put‎ significant‎ weight‎ upon‎ historical‎ practice.”)‎ (internal‎
    quotation marks omitted); NLRB v. Noel Canning, 
    134 S. Ct. 2550
    , 2560, slip op. at 7 (2014) (“[L]ongstanding practice of
    the government can inform our determination of what the law
    is.”)‎ (internal‎ quotation‎ marks‎ and‎ citations omitted); The
    Pocket Veto Case, 
    279 U.S. 655
    , 689 (1929) (“Long‎ settled‎
    and established practice is a consideration of great weight in a
    proper interpretation of constitutional provisions .‎ .‎ .‎ .”);‎
    McCulloch v. Maryland, 
    17 U.S. 316
    , 401 (1819) (when
    considering a separation of powers question, court should
    “receive‎ a‎ considerable‎ impression”‎ from‎ longstanding‎
    practice).
    In this case, turning first to the Legislative Branch,
    Congress’s‎ longstanding‎ practice‎ strongly‎ supports‎ the‎
    conclusion that international law is not a constitutional
    constraint‎ on‎ Congress’s‎ authority‎ to‎ make‎ particular crimes
    triable by military commission. From the earliest days of the
    13
    Republic, Congress has gone beyond international law in
    specifying the offenses that may be tried by military
    commission. Beginning in 1776, the Continental Congress
    codified the offense of spying – a non-international-law
    offense – as a crime triable by military tribunal. See
    Resolution of the Continental Congress (Aug. 21, 1776), in 5
    JOURNALS OF THE CONTINENTAL CONGRESS 1774 – 1789, at
    693 (Worthington Chauncey Ford ed. 1906) [hereinafter
    “JOURNALS”] (authorizing‎ trial‎ by‎ military‎ court‎ of‎ “all‎
    persons, not members of, nor owing allegiance to, any of the
    United States of America . . . who shall be found lurking as
    spies”);‎ see also WILLIAM WINTHROP, MILITARY LAW AND
    PRECEDENTS 765-66 & n.88 (rev. 2d ed. 1920). Likewise, in
    September 1776, Congress authorized trial by military
    tribunal for another non-international-law offense: aiding the
    enemy. See Articles of War (Sept. 20, 1776), in 5 JOURNALS,
    at 799. In 1789, after the Constitution was ratified, the First
    Congress adopted the same Articles of War that had been
    promulgated by the Continental Congress, including the
    offenses of spying and aiding the enemy. See Act of Sept. 29,
    1789, ch. 25, §4, 1 Stat. 95, 96 (1789). Again in 1806,
    Congress updated those provisions and, in doing so, was
    careful to preserve the offenses of spying and aiding the
    enemy as crimes triable by military tribunal. See Articles of
    War of 1806, ch. 20, arts. 56, 57, § 2, 2 Stat. 359, 366, 371
    (1806). Both of those prohibitions remain on the books today.
    See 10 U.S.C. §§ 950t(26), 950t(27). Congress has made
    those two crimes triable by military commission even though
    they are not international law of war offenses.
    Congress’s‎ practice‎ of‎ going‎ beyond international law
    has continued to the present. As recently as 2006 and 2009,
    Congress enacted new laws making several non-international-
    law offenses, such as solicitation and material support for
    terrorism, triable by military commission. See Military
    14
    Commissions Act of 2006, Pub. L. No. 109-366, 120 Stat.
    2600, 2630; Military Commissions Act of 2009, Pub. L. No.
    111-84, 123 Stat. 2574, 2611.
    That consistent congressional practice requires our
    respect.‎As‎the‎Supreme‎Court‎has‎stated,‎the‎“uniform, long-
    continued and undisputed legislative practice just disclosed
    rests upon an admissible view of the Constitution which, even
    if the practice found far less support in principle than we think
    it does, we should not feel at liberty at this late day to
    disturb.”‎ United States v. Curtiss-Wright Export Corp., 
    299 U.S. 304
    , 329 (1936).
    The joint dissent responds that Congress, over the course
    of more than two centuries, actually thought itself bound by
    international law but believed (mistakenly) that those offenses
    – spying and aiding the enemy, for example – were in fact
    international law offenses. See Dissenting Op. at 34-36. That
    assertion seems to materialize out of thin air. We are aware
    of no credible support for the notion that Congress has
    believed itself bound by international law in this context or
    has thought that those offenses were in fact international law
    offenses. Moreover, the joint dissent does not deal with the
    persistence of congressional practice – from the Founding to
    the recent 2006 and 2009 Acts. In short, the deeply rooted
    congressional‎ practice‎ directly‎ contradicts‎ the‎ joint‎ dissent’s‎
    position.
    Fifth, in addition to the historical practice in Congress,
    the historical practice in the Executive Branch demonstrates
    that international law is not a constraint on which offenses
    may be tried by military commissions. Indeed, perhaps the
    most telling factor when considering this constitutional
    question is the deeply rooted history of U.S. military
    commission trials of the offense of conspiracy, which is not
    15
    and has never been an offense under the international law of
    war. Cf. 
    Zivotofsky, 135 S. Ct. at 2091
    , slip‎ op.‎ at‎ 20‎ (“In‎
    separation-of-powers cases this Court has often put significant
    weight‎ upon‎ historical‎ practice.”)‎ (internal‎ quotation‎ marks‎
    omitted); Noel 
    Canning, 134 S. Ct. at 2560
    , slip op. at 7
    (“[L]ongstanding practice of the government can inform our
    determination‎ of‎ what‎ the‎ law‎ is”)‎ (internal‎ quotation‎ marks‎
    and citations omitted).
    The two most important military commission precedents
    in U.S. history – the trials of the Lincoln conspirators and the
    Nazi saboteurs – were trials for the offense of conspiracy.
    Consider the trial of the Lincoln conspirators. After
    seeking the advice of the Attorney General, President Andrew
    Johnson decided to try the Lincoln conspirators by military
    commission rather than by criminal trial in civilian court. See
    Military Commissions, 11 Op. Attorney Gen. 297, 298
    (1865). The Lincoln conspirators were expressly charged with
    and convicted of conspiracy – in that case, conspiracy to
    violate the law of war by killing the President and
    Commander in Chief of the Union Army, Abraham Lincoln.
    Indeed, conspiracy was the only offense charged against them.
    After an extensive multi-week trial that gripped the Nation
    and after vigorous argument about the facts and the
    commission’s‎ jurisdiction,‎ numerous‎ conspirators‎ were‎
    convicted of conspiracy.
    The joint dissent tries to cast doubt on whether the
    Lincoln conspirators were actually tried for conspiracy. There
    is no doubt. Consider what a contemporary court said in
    response to a habeas petition filed by three of the Lincoln
    conspirators:‎ ‎ “[T]he‎ prisoners‎ are‎ guilty‎ of‎ the‎ charge‎ on‎
    which they were convicted – of a conspiracy to commit the
    military crime which one of their number did commit, and
    16
    some‎of‎them‎of‎more‎or‎less‎participation.”‎‎Ex parte Mudd,
    
    17 F. Cas. 954
    (S.D. Fla. 1868).8 Indeed, in the prior en banc
    decision in this case, our Court (joined by one of the judges
    who joins the joint dissent today) described the Lincoln case
    as‎ a‎ trial‎ for‎ conspiracy‎ and‎ stated‎ that‎ “the‎ sole‎ offense‎
    alleged‎was‎conspiracy.”‎Al Bahlul v. United States, 
    767 F.3d 1
    , 25 (D.C. Cir. 2014) (en banc). Our en banc Court
    explained‎that‎the‎Lincoln‎case‎was‎a‎“particularly‎significant‎
    precedent”‎ and‎ a‎ “high-profile example of a conspiracy
    charge‎tried‎by‎a‎military‎commission.”‎Id.; see also Al Bahlul
    v. United States, 
    792 F.3d 1
    , 59-61 (D.C. Cir. 2015)
    (Henderson, J., dissenting).
    Consider also the military commission trial of the eight
    Nazi saboteurs who had been selected to execute Operation
    Pastorius – Adolf‎ Hitler’s‎ plan‎ to‎ destroy‎ America’s‎ war‎
    industries and facilities – and secretly entered the United
    States during World War II. The defendants were expressly
    charged with and convicted of conspiracy, as well as of other
    offenses. Attorney General of the United States Francis
    Biddle, who would later represent the United States as a judge
    at Nuremberg, personally prosecuted the case before the
    military commission. President Franklin Roosevelt reviewed
    and approved all of the convictions. The defendants filed
    habeas corpus petitions to block the proceedings as
    unconstitutional. The Supreme Court affirmed the legality of
    8
    Although the original records for the Southern District of
    Florida from that time period were initially lost, a copy of Judge
    Boynton’s‎ opinion‎ for‎ the‎ court‎ is on file with the Library of
    Congress. Moreover, the opinion was published in full in the New
    York Times on October 1, 1868 – precisely one month after the
    decision was handed down by the court. The Application in Behalf
    of Dr. Mudd, Arnold and Spangler – Opinion of Judge Boynton,
    N.Y. TIMES at 2 (Oct. 1, 1868).
    17
    the trial, and in doing so, did not disturb the conspiracy
    charge. See 
    Quirin, 317 U.S. at 46
    .
    Later in World War II, moreover, the Government
    prosecuted another set of Nazi saboteurs for conspiracy and
    tried them before a military commission. In that case,
    Assistant Attorney General Tom Clark, who would later serve
    on the Supreme Court, produced a formal memorandum –
    based in large part on the precedents involving the Lincoln
    conspirators and the earlier Nazi saboteurs – concluding that
    conspiracy was an offense triable by military commission.
    See Memorandum from Tom C. Clark, Assistant Attorney
    General, to Myron C. Kramer, Judge Advocate General (Mar.
    12, 1945), reprinted in Government Supplemental Appendix
    104-10.‎‎In‎Assistant‎Attorney‎General‎Clark’s‎words,‎it‎was‎
    “well‎ established‎ that‎ a‎ conspiracy‎ to‎ commit‎ an‎ offense‎
    against the laws of war is itself an offense cognizable by a
    commission‎ administering‎ military‎ justice.” 
    Id. at 110.
    The
    military commission subsequently convicted the defendants of
    conspiracy. President Truman reviewed and affirmed the
    convictions.     After one of those Nazi saboteurs later
    challenged his conviction in court, the Tenth Circuit affirmed
    the denial of his habeas petition, and the Supreme Court
    denied certiorari. The Tenth Circuit stated the charges against
    him‎ were‎ clearly‎ “within‎ the‎ jurisdiction‎ of‎ the‎ duly‎
    constituted Military Commission with power to try, decide
    and condemn.” Colepaugh v. Looney, 
    235 F.2d 429
    , 432 (10th
    Cir. 1956), cert. denied, 
    352 U.S. 1014
    (1957).
    Put simply, the most well-known and important U.S.
    military commissions in American history tried and convicted
    the defendants of conspiracy. That history matters. See
    
    Zivotofsky, 135 S. Ct. at 2091
    , slip op. at 20; Noel 
    Canning, 134 S. Ct. at 2559-60
    , slip op. at 6-7. And that history is
    directly on point here because conspiracy is not an
    18
    international law of war offense and because conspiracy is the
    precise offense that Bahlul was charged with committing.
    In response to all of this, the joint dissent says that there
    is‎no‎“robust‎history.”‎Dissenting‎Op.‎at‎37.‎‎But‎to‎reiterate,‎
    the two most important military commission trials in U.S.
    history were trials for conspiracy, which is not an
    international law of war offense. From the beginning of the
    Nation, Congress and the President have gone well beyond
    international law when enacting legislation making offenses
    triable by military commission.           To be sure, military
    commissions were not employed by the United States during
    the Korean War, the Vietnam War, or the Persian Gulf War.
    See Hamdan v. Rumsfeld, 
    548 U.S. 557
    , 597 (2006) (plurality
    opinion)‎(“The‎last‎time‎the‎U.S.‎Armed‎Forces‎used‎the‎law-
    of-war military commission was‎during‎World‎War‎II.”).9 So
    those wars do not supply us with any additional examples of
    military commission trials, and thus do not tell us anything
    one way or the other about trying conspiracy or other non-
    international-law offenses before military commissions.
    But in the two most significant U.S. wars of the last 200
    years – the Civil War and World War II – as well as in the
    current war against al Qaeda and its associated forces, the
    9
    In the Korean War, General Douglas MacArthur – who was
    serving as the head of the U.S. and United Nations forces in Korea
    – issued regulations specifying conspiracy to commit war crimes as
    an offense triable by military commission. See U.N. COMMAND,
    RULES OF CRIMINAL PROCEDURE FOR MILITARY COMMISSIONS OF
    THE UNITED NATIONS COMMAND at Rule 4 (Oct. 22, 1950)
    (establishing‎ that‎ “all‎ attempts‎ to‎ commit,‎ or‎ conspiracies‎ and‎
    agreements to commit . . . violations of the laws and customs of
    war”‎committed‎ during‎ the‎ Korean‎ War‎ were‎ to‎ be‎ punishable‎ by‎
    U.N. military commission). But no U.S. military commissions
    ultimately were convened during that war.
    19
    U.S. has employed military commissions. And the most
    important military commission trials during those wars were
    trials for conspiracy, which is not an international law of war
    offense. That historical and contemporary practice cannot be
    airbrushed out of the picture. Prosecuting conspiracy and
    other non-international-law-of-war offenses is not at the
    periphery of U.S military commission history and practice.
    Prosecuting conspiracy and other non-international-law-of-
    war offenses lies at the core of U.S. military commission
    history and practice.
    As the Supreme Court cautioned in Noel Canning, we
    must‎ be‎ “reluctant to upset this traditional practice where
    doing so would seriously shrink the authority that Presidents
    have‎ believed‎ existed‎ and‎ have‎ exercised‎ for‎ so‎ long.”‎ Noel
    
    Canning, 134 S. Ct. at 2573
    . Moreover, the Supreme Court
    has explained that historical‎practice‎constitutes‎“an‎important‎
    interpretive factor even when the nature or longevity of that
    practice is subject to dispute, and even when that practice
    began‎after‎the‎founding‎era.”‎Id. at 2560.
    In short, the text and original understanding of the
    Constitution; the structure of the Constitution; landmark
    Supreme Court precedent; the deeply rooted historical
    practice of the Legislative Branch, as seen in federal statutes;
    and the longstanding practice of the Executive Branch, as
    seen in U.S. military commission practice stretching back
    over two centuries, all point decisively to the same
    conclusion: The war powers clauses of Article I of the
    Constitution do not impose international law as a constraint
    on Congress’s‎ authority‎ to‎ establish‎ offenses‎ triable‎ by‎
    military commission.
    20
    II
    Bahlul also contends that Article III of the U.S.
    Constitution confines U.S. military commissions to
    international law of war offenses.
    This‎ iteration‎ of‎ Bahlul’s argument begins with the
    premise that Article III vests the judicial power in Article III
    courts and requires crimes to be tried by jury, not before
    military commissions.10 Based solely on the text of Article
    III, Bahlul might have a point. But the Supreme Court has
    long recognized an exception to Article III for military
    commissions to try enemy war crimes. See Ex Parte Quirin,
    
    317 U.S. 1
    , 38-45 (1942); see also Hamdan v. Rumsfeld, 
    548 U.S. 557
    (2006).
    Exceptions to Article III, including the exception for
    military commissions, are established and interpreted in light
    of historical practice. See Northern Pipeline Construction Co.
    v. Marathon Pipe Line Co., 
    458 U.S. 50
    , 64 (1982) (plurality
    opinion) (“[T]he literal command of Art. III . . . must be
    interpreted in light of the historical context in which the
    Constitution was written, and of the structural imperatives of
    the‎ Constitution‎ as‎ a‎ whole.”);‎ Quirin 317‎ U.S.‎ at‎ 39‎ (“[I]t‎
    was not the purpose or effect of § 2 of Article III, read in the
    light of the common law, to enlarge the then existing right to
    a‎ jury‎ trial.”);‎ see also Stern v. Marshall, 
    564 U.S. 462
    ,
    504-05 (2011)‎(Scalia,‎J.,‎concurring)‎(“[A]n Article III judge
    is required in all federal adjudications, unless there is a firmly
    established historical practice to the contrary.”);‎see generally
    10
    See U.S. CONST. art.‎ III,‎ §‎ 1‎ (“The‎ judicial‎ Power of the
    United‎States,‎shall‎be‎vested‎.‎.‎.‎.”);‎id. §‎2,‎cl.‎3‎(“The‎Trial‎of‎all‎
    Crimes, except in Cases of Impeachment, shall be by
    Jury‎.‎.‎.‎.”).
    21
    Zivotofsky v. Kerry, 
    135 S. Ct. 2076
    , 2091, slip op. at 20
    (2015) (“In‎ separation-of-powers cases this Court has often
    put significant weight upon historical‎ practice.”) (internal
    quotation marks omitted); Youngstown Sheet & Tube Co. v.
    Sawyer, 
    343 U.S. 579
    , 610 (1952) (Frankfurter, J.,
    concurring)‎ (“Deeply‎ embedded‎ traditional‎ ways‎ of‎
    conducting government cannot supplant the Constitution or
    legislation, but they give meaning to the words of a text or
    supply‎ them.”);‎ The Pocket Veto Case, 
    279 U.S. 655
    , 689
    (1929)‎ (“Long‎ settled‎ and‎ established‎ practice‎ is‎ a‎
    consideration of great weight in a proper interpretation of
    constitutional provisions of this character.”);‎ McCulloch v.
    Maryland,‎ 17‎ U.S.‎ 316,‎ 401‎ (1819)‎ (“[A]‎ doubtful‎ question,‎
    one on which human reason may pause, and the human
    judgment be suspended, in the decision of which the great
    principles of liberty are not concerned, but the respective
    powers of those who are equally the representatives of the
    people, are to be adjusted; if not put at rest by the practice of
    the government, ought to receive a considerable impression
    from‎that‎practice.”).
    In this context, if historical practice demonstrates that an
    offense is triable by U.S. military commission, that history
    resolves the Article III issue. As explained in Part I of this
    opinion, the history of U.S. military commissions trying non-
    international-law-of-war offenses is extensive and dates from
    the beginning of the Republic. That historical practice
    therefore amply demonstrates that Article III is not a barrier to
    U.S. military commission trials of non-international-law-of-
    war offenses, including the offense of conspiracy to commit
    war crimes.
    Notwithstanding that history, Bahlul says that Quirin
    already considered the military commission exception to
    22
    Article III and limited the exception to international law of
    war offenses.
    Bahlul’s‎ reading‎ of‎ Quirin is incorrect. In Quirin, the
    Nazi saboteur defendants claimed that they had a right under
    Article III to be tried by jury in an Article III federal court and
    therefore could not be tried by military commission. At some
    length, the Quirin Court specifically considered and rejected
    the defendants’‎Article‎III‎objection.‎‎See 
    Quirin, 317 U.S. at 38-45
    .11 The Court explained that Article III did not “enlarge
    the‎ then‎ existing‎ right‎ to‎ a‎ jury‎ trial”‎ beyond‎ the‎ right‎ as‎ it‎
    existed at common law. 
    Id. at 39.
    Because the common law
    did not preclude trial by military commission for war crimes,
    Article‎ III‎ “cannot‎ be‎ taken‎ to‎ have‎ extended‎ the‎ right‎ to‎
    demand a jury to trials by military commission, or to have
    required that offenses against the law of war not triable by
    jury‎at‎common‎law‎be‎tried‎only‎in‎the‎civil‎courts.”‎‎ 
    Id. at 40.
    As explained above, in reaching its conclusion on the
    Article III issue, the Quirin Court emphasized that Congress –
    exercising its Article I powers – had made spying an offense
    triable by military commission since the earliest days of the
    Republic.‎ ‎ The‎ Court‎ stated‎ that‎ the‎ early‎ Congress’s‎
    enactment‎ of‎ the‎ spying‎ statute‎ “must‎ be‎ regarded‎ as‎ a‎
    contemporary‎construction”‎of‎Article‎III‎“as‎not‎foreclosing‎
    trial by military tribunals, without a jury, of offenses against
    the law of war committed by enemies not in or associated
    with‎ our‎ Armed‎ Forces.”‎ ‎ 
    Id. at‎ 41.‎
    ‎ “Such‎ a‎ construction,”‎
    the‎Court‎said,‎“is‎entitled‎to‎the‎greatest‎respect.”‎‎Id. at 41-
    42.
    11
    The Court also referred to the Fifth and Sixth Amendments
    when talking about Article III, but the Court analyzed them
    together. For ease of reference, we will refer only to Article III.
    23
    The‎Supreme‎Court’s‎analysis in Quirin is instructive for
    present purposes because, as noted above, the offense of
    spying on which the Quirin Court relied to answer the Article
    III objection was not (and is not) an offense under the
    international law of war. It thus makes little sense to read
    Quirin as barring military commission trials of non-
    international-law-of-war offenses when Quirin, in rejecting a
    jury trial objection to military commissions, expressly relied
    on a longstanding statute making spying – a non-
    international-law-of-war offense – triable by military
    commission.
    In addition, as previously discussed, nothing about the
    Court’s‎ reasoning‎ in‎ Quirin rested on whether the offense
    tried by a military commission was an international law of
    war offense. The Court never suggested that military
    commissions are constitutionally permitted only for
    international law of war offenses. Nor has the Court ever said
    anything like that in its several later military commission
    cases. One would have expected the Court to say as much if
    the Court actually thought as much.
    To be sure, the Quirin Court referred to international law
    authorities. But as noted above, the Court discussed those
    authorities‎ in‎ part‎ because‎ an‎ offense’s‎ status‎ as‎ an‎
    international law offense is sufficient but not necessary to
    make an offense triable by military commission under 10
    U.S.C.‎ §‎ 821,‎ the‎ statute‎ that‎ used‎ the‎ broad‎ term‎ “law‎ of‎
    war”‎to‎define‎offenses‎triable‎by‎military‎commission.‎
    In short, Article III does not limit U.S. military
    commissions to international law of war offenses or otherwise
    24
    foreclose trial of the offense of conspiracy to commit war
    crimes before U.S. military commissions.12
    All of that said, the Constitution does not grant Congress
    unlimited authority to designate crimes as triable by military
    commission. At oral argument, the Government stated that
    the charges must at least involve an enemy combatant who
    committed a proscribed act during or in relation to hostilities
    against the United States. See Tr. of Oral Arg. at 37. In
    general, if an offense is an international law of war offense or
    has historically been tried by U.S. military commission, that is
    sufficient to‎ uphold‎ Congress’s‎ constitutional‎ authority‎ to‎
    make the offense triable by military commission. See
    generally 
    Quirin, 317 U.S. at 24-48
    . As Winthrop explained,
    the war crimes triable by U.S. military commission are
    “derived‎ from‎ International‎ Law,‎ supplemented‎ by‎ acts‎ and‎
    orders‎of‎the‎military‎power‎and‎a‎few‎legislative‎provisions.”
    WILLIAM WINTHROP, MILITARY LAW AND PRECEDENTS 773
    (rev. 2d ed. 1920).
    But is one of those conditions necessary? In other words,
    what if an offense is neither an international law of war
    offense nor historically rooted in U.S. military commission
    practice? Consider a hypothetical new statute that makes
    cyber-attacks by enemy forces a war crime triable by military
    commission. Quirin stated‎ that‎ Article‎ III‎ does‎ “not‎ restrict‎
    whatever authority was conferred by the Constitution to try
    offenses‎against‎the‎law‎of‎war‎by‎military‎commission,”‎and‎
    does‎not‎bar‎“the‎practice‎of‎trying,‎before‎military‎tribunals‎
    without a jury, offenses committed by enemy belligerents
    12
    Bahlul also has raised equal protection and First
    Amendment challenges to his conviction. Those arguments are
    frivolous, for reasons explained in Al Bahlul v. United States, 
    767 F.3d 1
    , 75-76 (D.C. Cir. 2014) (en banc) (separate opinion of
    Kavanaugh, J.).
    25
    
    against‎the‎law‎of‎war.”‎‎Quirin, 317 U.S. at 45
    , 41. Perhaps
    that language suggests that Article III permits what Article I
    authorizes with respect to which enemy war crimes may be
    tried by U.S. military commission. But we need not answer
    that hypothetical in this case and need not define with
    precision the outer limits of the Constitution in this context,
    other than to say that international law is not such a limit.
    Wherever one might ultimately draw the outer boundaries of
    Congress’s‎ authority‎ to‎ establish‎ offenses‎ triable‎ by‎ military‎
    commission, the historically rooted offense of conspiracy to
    commit war crimes is well within those limits. An enemy of
    the United States who engages in a conspiracy to commit war
    crimes – in‎Bahlul’s‎case,‎by‎plotting‎with‎Osama‎bin‎Laden‎
    to murder thousands of American civilians – may be tried by
    a U.S. military commission for conspiracy to commit war
    crimes.
    III
    In light of the importance of this case, and the serious and
    passionate arguments advanced by the joint dissent, we close
    with a few additional responses to points made by the joint
    dissent.
    First, in reaching its conclusion, the joint dissent relies in
    part on Hamdan v. Rumsfeld, 
    548 U.S. 557
    (2006). That
    reliance is misplaced. As relevant here, Hamdan was a
    statutory‎ case‎ interpreting‎ the‎ phrase‎ “law‎ of‎ war”‎ in‎ 10‎
    U.S.C. § 821. Nowhere did the Supreme Court ever say (or
    even hint) that the United States Constitution imposed
    international law as a limit on what offenses may be tried by
    U.S.‎ military‎ commissions.‎ The‎ joint‎ dissent’s‎ citations‎ to‎
    Hamdan therefore do not support its constitutional position.
    26
    In fact, the Hamdan decision and its aftermath only
    highlight the extraordinary nature‎ of‎ the‎ joint‎ dissent’s‎
    position. In Hamdan, the Court confronted but ultimately did
    not resolve the question of whether the relevant statute in
    effect at the time, 10 U.S.C. § 821, barred military
    commission trials of alleged war criminals for conspiracy.
    But four of the Justices in the majority expressly invited
    Congress to clarify the scope of military commission power.
    
    Hamdan, 548 U.S. at 636
    (Breyer, J., concurring, joined by
    Kennedy, Souter, and Ginsburg, JJ.); 
    id. at 653
    (Kennedy, J.,
    concurring in part, joined in relevant part by Souter,
    Ginsburg,‎ and‎ Breyer,‎ JJ.).‎ ‎ ‎ In‎ response‎ to‎ the‎ Justices’‎
    invitation, Congress and the President promptly enacted new
    legislation to make crystal clear that conspiracy is an offense
    triable by military commission. Military Commissions Act of
    2006, Pub. L. No. 109-366, 120 Stat. 2600, 2625, 2630
    (expressly authorizing trials before military commissions for
    conspiracy offenses).
    A decade after Hamdan, Bahlul and the joint dissent have
    now come back with a novel and extraordinary constitutional
    interpretation that would thwart the considered wartime
    decisions of two Congresses and two Presidents – decisions
    invited by the Supreme Court in Hamdan – to authorize
    military commission trials of conspiracy offenses. Under the
    joint‎dissent’s‎theory,‎the‎congressional‎action‎invited‎by‎the‎
    Supreme Court was all a waste of time because U.S. military
    commissions are constitutionally barred from trying the
    offense of conspiracy, regardless of statutory authorization.
    But in Hamdan, not a single Justice hinted at a lurking
    constitutional problem with trying conspiracy offenses before
    military commissions (nor did Hamdan himself in his
    arguments to the Supreme Court, either directly or through a
    constitutional avoidance argument). To be sure, the Hamdan
    decision does not formally preclude the Supreme Court from
    27
    now returning to the scene and finding a previously missed
    constitutional problem with trying conspiracy offenses by
    military commission. But in this wartime context, one should
    not lightly assume that the Supreme Court expressly
    encouraged the political branches to launch into an utterly
    meaningless, decade-long exercise.
    Second,‎the‎joint‎dissent‎says:‎“It‎is‎not‎international‎law,‎
    however, that constrains Congress’s‎ authority‎ here‎ – it is
    Article‎III.”‎‎Dissenting‎Op.‎at‎46.‎That‎sentence‎glides‎over‎
    the key question. The question is whether Article III (or
    Article I) incorporates international law as a constraint on
    U.S. military commissions. The joint dissent says yes. But
    the constitutional text and structure, Supreme Court
    precedents, and deeply rooted U.S. history tell us that the
    answer is no.
    Of course, the consistent U.S. history is the consistent
    U.S. history for a reason. As explained above, the
    consequences for the United States of judicially incorporating
    international law into the U.S. Constitution would be deeply
    problematic and run afoul of our most fundamental
    constitutional principles and traditions. International law
    often embodies a majority or consensus view of nations.
    Does the United States Constitution really allow foreign
    nations, through the guise of international law, to set
    constitutional limits enforceable in U.S. courts against the
    U.S.‎ war‎ effort?‎ ‎ Under‎ Bahlul’s‎ argument,‎ and‎ under the
    theory advanced by the joint dissent, the answer would be yes.
    We think not. We see no basis in U.S. law, precedent, or
    history – not to mention, common sense – for that position.
    To‎ paraphrase‎ Justice‎ Jackson,‎ the‎ Constitution‎ is‎ not‎ “a‎
    suicide pact.”‎‎Terminiello v. Chicago, 
    337 U.S. 1
    , 37 (1949)
    (Jackson, J., dissenting).
    28
    To be sure, the Judiciary plays a critical role in enforcing
    constitutional and statutory limits in justiciable wartime cases,
    and this Court must not hesitate (and has not hesitated) in
    doing so, even when the consequences are significant. See
    Youngstown Sheet & Tube Co. v. Sawyer, 
    343 U.S. 579
    (1952); Al Bahlul v. United States, 
    767 F.3d 1
    (D.C. Cir.
    2014) (en banc) (Ex Post Facto Clause bars Congress and the
    President from making material support for terrorism a war
    crime that can be retroactively prosecuted before a military
    commission); Hamdan v. United States, 
    696 F.3d 1238
    (D.C.
    Cir. 2012) (same, via constitutional avoidance doctrine). But
    in this case, neither Article I nor Article III confines Congress
    to international law of war offenses when Congress
    establishes war crimes triable by military commission.
    To be clear, we take no position on the policy question of
    whether the U.S. Government should use military
    commissions to try the offense of conspiracy or other non-
    international-law-of-war offenses, or indeed whether the
    Government should use military commissions at all. That
    policy decision belongs first to Congress and the President in
    the legislative process, and then to the President in the
    exercise of his or her Commander-in-Chief power. Likewise,
    we take no position on the general question of when and how
    Congress and the President should weigh international law
    principles in making those decisions. International law is
    important, and the political branches have good reason to
    adhere to international law when determining what offenses
    will be tried before U.S. military commissions. But
    international law has its own enforcement mechanisms. The
    federal courts are not roving enforcers of international law.
    And the federal courts are not empowered to smuggle
    international law into the U.S. Constitution and then wield it
    as a club against Congress and the President in wartime.
    29
    Third, the joint dissent seeks to explain away the history
    and practice of U.S. military commissions. But that effort is
    entirely unpersuasive.
    In the face of the deeply rooted U.S. history and practice
    of trying conspiracy offenses by military commission, the
    joint dissent had two options.          It could discount the
    importance of history to the constitutional analysis, and try to
    explain that the constitutional text and structure matter most
    here. The joint dissent did not choose that approach, no doubt
    because the constitutional text and structure also show what
    the history shows: that international law is not a constraint on
    Congress when Congress determines which offenses may be
    tried by military commission.
    Alternatively, the joint dissent could attack the history
    head-on on the theory that the history does not actually show
    what it seems to show. That is the route that the joint dissent
    chose. But it does not work. Consider all of the contortions
    the joint dissent has to make in attempting to wriggle out of
    the history. First, faced with the historical fact that Congress
    since the Founding has consistently made non-international-
    law offenses triable by military commission, the joint dissent
    unconvincingly posits that those Congresses all mistakenly
    believed that those offenses actually were international law
    offenses (even though they were not and even though there is
    no persuasive evidence that Congress thought they were). See
    Dissenting Op. at 34-35. Second, faced with the historical
    fact‎that‎the‎Executive‎Branch’s‎two‎most‎important military
    commissions in the history of the country were trials of
    conspiracy offenses, which are not international law offenses,
    the joint dissent implausibly suggests that the Lincoln case
    was not really a conspiracy case (even though it plainly was),
    and it notes that the conspiracy charges against the eight
    Nazis at issue in Quirin were never directly reviewed by a
    30
    court (even though the relevant point is that the military
    commission trial of the Nazis for conspiracy remains a central
    part of Executive Branch historical practice). See 
    id. at 37-39,
    42-44. Third, faced with the fact that the Supreme Court
    relied on a non-international-law offense, spying, in its
    landmark Quirin decision upholding military commissions,
    the joint dissent seeks to sweep that inconvenient snippet
    under the rug by suggesting that the Court mistakenly
    believed that spying was an international law offense (even
    though there is no persuasive evidence that the Court actually
    thought as much). See 
    id. at 25-26.
    The bottom line here is that the history matters, the
    history is overwhelming, and the history devastates the joint
    dissent’s‎position.‎
    Fourth, in justifying its position, the joint dissent posits a
    hypothetical of non-U.S.-citizens living together in an
    apartment in Virginia with pipe bombs, al Qaeda propaganda,
    and a map of the Washington Metro. The joint dissent says it
    would‎be‎“dangerous”‎to‎apprehend‎such‎a‎group‎and‎then‎try‎
    them for conspiracy before a military commission.
    Dissenting Op. at 63-64. We are mystified by the joint
    dissent’s‎apparent‎belief‎that‎this‎is‎a‎helpful‎hypothetical‎for‎
    its position. We take it that the point of the hypothetical is to
    suggest that military commissions should not be used to try
    non-citizen enemy terrorists who are (i) captured in the
    United States (ii) before they commit their planned attacks.
    Of course, the current war has no such neat geographical
    boundaries. And neither did World War II, for that matter.
    After all, the Nazi saboteurs were captured in the United
    States before their planned attacks on U.S. facilities. They
    were then prosecuted before U.S. military commissions. And
    if Mohamad Atta and his fellow attackers had been captured
    on the night of September 10, 2001, in Portland, Maine, and
    31
    elsewhere, and then tried before congressionally authorized
    U.S. military commissions for conspiracy, we certainly would
    not‎have‎characterized‎that‎scenario‎as‎“dangerous.”
    Fifth, the joint dissent insists that the mission of the
    military is to defeat enemies on the battlefield, not to punish
    enemy wrongdoers. See Dissenting Op. at 49-50. The
    dissent’s‎effort‎to‎define‎U.S.‎military‎strategy‎in‎that‎way‎is‎
    both legally and factually flawed. As the Supreme Court has
    long recognized, including in landmark cases such as Hamdi,
    war is waged not only by killing enemy combatants, but also
    by surveilling, capturing, and detaining enemy forces, and by
    trying unlawful enemy combatants for war crimes. And in the
    current war, the modus operandi of the enemy is to target
    citizens; to frighten, unsettle, disrupt, and demoralize; to
    make normal peaceful life impossible and carnage routine. In
    response‎ to‎ the‎ enemy’s‎ tactics,‎ two‎ Congresses‎ and‎ two‎
    Presidents – like their predecessors throughout U.S. history –
    have determined that employing military commissions to try
    unlawful enemy combatants for their war crimes is an
    important part of the overall war effort. The Constitution
    assigns that question of military strategy to Congress and the
    President, not to the joint dissenters.
    Sixth, and relatedly, in seeking to minimize the
    consequences of its theory, the joint dissent suggests that
    military commissions are not essential to the U.S. war effort
    because the U.S. Government can simply try al Qaeda war
    criminals in federal courts, including for conspiracy to
    commit war crimes. See, e.g., Dissenting Op. at 1, 47-48.
    With all respect, the joint dissent has no business making such
    a statement. It has no basis to express such confidence and no
    relevant expertise on that question of wartime strategy.
    Unlike the joint dissenters, Presidents Bush and Obama, as
    well as the two Congresses in 2006 and 2009, determined that
    32
    the ordinary federal court process is not suitable for trying
    certain enemy war criminals. The only question for us as
    judges is one of law: whether the U.S. Constitution permits
    that policy choice by Congress and the President. If the
    answer were no, then we would enforce the Constitution. Cf.
    Hamdi v. Rumsfeld, 
    542 U.S. 507
    , 577 (2004) (Scalia, J.,
    dissenting). But here, the answer is yes.
    ***
    We‎ vote‎ to‎ affirm‎ Bahlul’s‎ conviction‎ for‎ conspiracy
    to commit war crimes.
    MILLETT, Circuit Judge, concurring: “[T]here is no
    liberty if the power of judging be not separated from the
    Legislative and Executive powers.” THE FEDERALIST NO. 78,
    at 425 (Alexander Hamilton) (E.H. Scott ed. 1898) (citation
    omitted). Under our system of separated powers, that means
    that the Judicial Branch bears both distinct responsibilities
    and distinct constraints. In particular, the Judicial Branch
    must declare and enforce the Constitution’s limitations
    against the actions of the Political Branches in cases when
    that is necessary. And we must not do so when it is not
    necessary. “After all, a longstanding principle of judicial
    restraint requires that courts avoid reaching constitutional
    questions in advance of the necessity of deciding them.” 1
    Pursuant to the Military Commissions Act of 2006
    (“2006 Act”), Pub. L. No. 109-366, 120 Stat. 2600, a military
    commission found petitioner Hamza Ahmad Suliman al
    Bahlul guilty of conspiracy to violate the law of war, in
    violation of 10 U.S.C. § 950v(b)(28). The parties framed for
    our review the important constitutional questions of whether a
    conviction for inchoate conspiracy by an Article I military
    commission either exceeds Congress’s legislative authority
    under Article I or violates Article III’s assignment of the
    judicial power to the federal courts.
    I would decline to resolve those constitutional questions
    because they are not directly presented by this case. First,
    Bahlul forfeited those challenges by failing to raise them
    1
    Camreta v. Greene, 
    563 U.S. 692
    , 705 (2011) (internal quotation
    marks and citation omitted); see also Ashwander v. Tennessee
    Valley Authority, 
    297 U.S. 288
    , 346–347 (1936) (Brandeis, J.,
    concurring) (explaining that courts should not “anticipate a question
    of constitutional law in advance of the necessity of deciding it”;
    neither should they “formulate a rule of constitutional law broader
    than is required by the precise facts to which it is to be applied”).
    2
    before the military commission, making plain-error review
    appropriate.
    Second, whatever broad constitutional issues may lurk
    within the 2006 Act, Bahlul challenges only his judgment of
    conviction, and thus the application of the 2006 Act’s
    conspiracy provision to him in this prosecution. See Oral
    Arg. Tr. 6; Pet. Br. 57. And the conspiracy for which Bahlul
    was convicted rested on proof of more statutory elements than
    ordinary inchoate conspiracy requires, including intent to
    further the commission of war crimes, Pet. Supp. App. 137,
    and proof of an overt act in furtherance of a violation of the
    law of war, 
    id. In addition,
    the conspiracy’s objects included
    completed war crimes. 
    Id. Third, the
    specific findings made by the commission, on
    which Bahlul’s conviction rests, largely eliminated the gap
    between his conviction and those types of conspiracies that
    are indisputably triable by military commission. Whatever
    remaining distance Congress might have closed in an exercise
    of its power to define and punish violations of the law of
    nations does not, in my view, amount to plain constitutional
    error.
    Finally, I join the court’s determination that Bahlul’s
    First Amendment and Equal Protection claims are
    foreclosed. 2
    2
    I refer to the defendant as Bahlul, rather than al Bahlul, because
    that is the appellation employed by his counsel on his behalf.
    3
    I
    A
    This case concerns Bahlul’s conviction by a military
    commission of conspiracy to violate the law of war, as that
    offense is defined in 10 U.S.C. § 950v(b)(28). A person
    commits conspiracy under Section 950v(b)(28) if he
    “conspires to commit one or more substantive offenses triable
    by military commission under this chapter, and * * *
    knowingly does any overt act to effect the object of the
    conspiracy.” 10 U.S.C. § 950v(b)(28). The substantive
    offenses triable by military commission under the chapter
    include murder of protected persons, attacking civilians,
    attacking civilian objects, murder in violation of the law of
    war, destruction of property in violation of the law of war,
    terrorism, and providing material support for terrorism. See
    
    id. § 950v(b)(1),
    (2), (3), (15), (16), (24) & (25). The 2006
    Act further provides that conspiracy “shall be punished, if
    death results to one or more of the victims, by death or other
    such punishment as a military commission under this chapter
    may direct, and, if death does not result to any of the victims,
    by such punishment, other than death, as a military
    commission under this chapter may direct.” 
    Id. § 950v(b).
    In what is known as the “Define and Punish Clause,”
    Article I of the Constitution empowers Congress to “define
    and punish * * * Offences against the Law of Nations.” U.S.
    CONST., Art. I, § 8, cl. 10. The Supreme Court has explained
    that “[o]ffences * * * against the law of nations, cannot, with
    any accuracy, be said to be completely ascertained and
    defined in any public code recognized by the common
    consent of nations.” United States v. Smith, 
    18 U.S. 153
    , 158
    (1820). Thus, “there is a peculiar fitness in giving the power
    to define as well as to punish” to Congress, “and there is not
    4
    the slightest reason to doubt that this consideration had very
    great weight in producing the phraseology in question.” Id.;
    see Ex parte Quirin, 
    317 U.S. 1
    , 28 (1942).
    At the same time, Congress’s power to punish offenses
    by military commission is constrained by the Constitution’s
    Judicial Power Clause, Art. III, § 2, cl. 1. That Clause
    provides that “[t]he judicial Power shall extend to all Cases,
    in Law and Equity, arising under this Constitution, the Laws
    of the United States, and Treaties made, or which shall be
    made, under their Authority,” and “to Controversies to which
    the United States shall be a Party.” 
    Id. Those “Cases”
    and
    “Controversies” include criminal prosecutions. See United
    States ex rel. Toth v. Quarles, 
    350 U.S. 11
    , 15 (1987). If a
    suit falls within the judicial power, then “the responsibility for
    deciding that suit rests with Article III judges in Article III
    courts,” and the Constitution forbids Congress to assign its
    resolution to another tribunal. See Stern v. Marshall, 
    564 U.S. 462
    , 484 (2011).
    B
    While our prior en banc opinion catalogued the factual
    background of this case, see Bahlul v. United States (Bahlul
    I), 
    767 F.3d 1
    , 5–8 (D.C. Cir. 2014) (en banc), portions of that
    factual history help to frame the legal questions that Bahlul
    presents.
    Bahlul is a native of Yemen. In the late 1990s, he
    traveled to Afghanistan to join al Qaeda, and there he met
    Usama bin Laden. On October 12, 2000, al Qaeda attacked
    the USS Cole, killing seventeen American sailors and injuring
    thirty-nine others. Bahlul created a recruiting video for al
    Qaeda celebrating that attack, which he considered one of the
    best recruiting videos al Qaeda had produced. Pet. App. 134;
    see Bahlul 
    I, 767 F.3d at 5
    .
    5
    Bin Laden subsequently appointed Bahlul his personal
    assistant and secretary for public relations. Bahlul actively
    prepared for al Qaeda’s attacks on the United States on
    September 11, 2001. He arranged the loyalty oaths and
    prepared “martyr wills” for Mohamed Atta and Ziad al Jarrah,
    two of the hijackers who flew planes into the World Trade
    Center. Those “martyr wills” were propaganda declarations
    made in preparation for the attack and in which Atta and al
    Jarrah documented their and al Qaeda’s roles in the atrocities.
    Bahlul also provided research to bin Laden regarding the
    economic effects of the attacks.          In addition, Bahlul
    volunteered to participate in the 9/11 attacks himself, but bin
    Laden thought he was too important to lose. Just before 9/11,
    Bahlul evacuated al Qaeda’s headquarters in Afghanistan with
    bin Laden and other senior al Qaeda leaders. Bahlul 
    I, 767 F.3d at 6
    . After the attacks, Bahlul fled to Pakistan, where he
    was captured and turned over to the United States military.
    
    Id. at 6.
    As relevant here, the United States charged Bahlul under
    the 2006 Act with conspiracy to commit war crimes. See 10
    U.S.C. § 950v(b)(28). Bahlul was tried before a military
    commission convened at Guantanamo Bay. During the trial,
    Bahlul “flatly refused to participate in the military
    commission proceedings and instructed his trial counsel not to
    present a substantive defense.” Bahlul 
    I, 767 F.3d at 10
    . At
    no time did he raise any argument that Congress lacked the
    constitutional power to authorize a trial by military
    commission for conspiracy, or that in doing so, Congress ran
    afoul of the Define and Punish Clause or the Judicial Power
    Clause.
    Before its deliberations, the commission was instructed
    that, to convict Bahlul of conspiracy under the 2006 Act, it
    must find “beyond a reasonable doubt” that Bahlul “entered
    6
    into an agreement” with other members of al Qaeda to
    commit a substantive offense under the Act, “knew the
    unlawful purpose of the agreement and joined in it willingly,”
    and “knowingly committed” an overt act to bring about one of
    the objects of the agreement. Pet. Supp. App. 137. The
    military commission subsequently found Bahlul guilty of
    conspiracy under 10 U.S.C. § 950v(b)(28). In so doing, the
    commission specifically found that Bahlul committed ten
    overt acts as part of the conspiracy:
    1. Traveled to Afghanistan with the purpose and intent of
    joining al Qaeda;
    2. Met with Saif al’Adl, the head of the al Qaeda
    Security Committee, as a step toward joining the al
    Qaeda organization;
    3. Underwent military-type training at an al Qaeda
    sponsored training camp then located in Afghanistan;
    4. Pledged fealty, or “bayat,” to the leader of al Qaeda,
    Usama bin Laden, joined al Qaeda, and provided
    personal services in support of al Qaeda;
    5. Prepared and assisted in the preparation of various
    propaganda products, including the video “The
    Destruction of the American Destroyer U.S.S. Cole,”
    to solicit material support for al Qaeda, to recruit and
    indoctrinate personnel to the organization and
    objectives of al Qaeda, and to solicit, incite and advise
    persons to commit Terrorism;
    6. Acted as personal secretary and media secretary of
    Usama bin Laden in support of al Qaeda;
    7. Arranged for Muhammed Atta, also known as Abu
    Abdul Rahman al Masri, and Zaiad al Jarrah, also
    known as Abu al Qa’qa al Lubnani, to pledge fealty or
    “bayat,” to Usama bin Laden;
    8. Prepared the propaganda declarations styled as martyr
    wills for two of the 9/11 hijackers, Muhammed Atta
    7
    and Ziad al Jarrah, in preparation for the acts of
    terrorism perpetrated by them in the United States on
    September 11, 2001;
    9. At the direction of Usama bin Laden, researched the
    economic effects of the September 11, 2001, attacks
    on the United States, and provided the results to
    Usama bin Laden; and
    10. Operated and maintained data processing equipment
    and media communications equipment for the benefit
    of Usama bin Laden and other members of the al
    Qaeda leadership.
    Pet. App. at 116–117.
    The commission also found Bahlul guilty of conspiracy
    to commit seven charged object offenses: (i) murder of
    protected persons, (ii) attacking civilians, (iii) attacking
    civilian objects, (iv) murder in violation of the law of war, (v)
    destruction of property in violation of the law of war, (vi)
    terrorism, and (vii) providing material support for terrorism.
    Pet. App. 115; see 10 U.S.C. § 950(v)(b)(1), (3), (15), (16),
    (24) & (25). The military commission sentenced Bahlul to
    life imprisonment. Pet. App. 86.
    II
    A
    Before wading into any constitutional dispute, courts
    must first decide how deeply they should go—that is, which
    standard of review should apply. Those review standards are
    critical components of our justice system because they
    promote fairness, stability, and finality within the judicial
    process, and they give effect to the relative expertise of both
    the appellate court and the tribunals whose judgments are
    under review. See Puckett v. United States, 
    556 U.S. 129
    , 134
    8
    (2009); United States v. Frady, 
    456 U.S. 152
    , 163 (1982)
    (Standards of review “encourage all trial participants to seek a
    fair and accurate trial the first time around[.]”).
    Ordinarily, questions of constitutional law in criminal
    cases are decided de novo, and we plunge into plenary review.
    See, e.g., United States v. Straker, 
    800 F.3d 570
    , 629 (D.C.
    Cir. 2015). But this case is not ordinary. Bahlul seeks to
    overturn his conviction on the basis of constitutional
    arguments that he could have made before the military
    commission, but did not. Bahlul nonetheless insists that we
    must consider his challenges de novo. See Pet. Br. 41.
    Bahlul is wrong, in my view. Appellate courts are
    supposed to be courts of review, not first view. See
    Zivotofsky ex rel. Zivotofsky v. Clinton, 
    132 S. Ct. 1421
    , 1430
    (2012). And “‘[n]o procedural principle is more familiar
    * * * than that a constitutional right,’ or a right of any other
    sort, ‘may be forfeited in criminal as well as civil cases by the
    failure to make timely assertion of the right before a tribunal
    having jurisdiction to determine it.’” United States v. Olano,
    
    507 U.S. 725
    , 731 (1993) (quoting Yakus v. United States,
    
    321 U.S. 414
    , 444 (1944)); United States v. Baucum, 
    80 F.3d 539
    , 541 (D.C. Cir. 1996) (noting “established Supreme Court
    precedent declining to address constitutional questions not put
    in issue by the parties”); see also, e.g., United States v. David,
    
    96 F.3d 1477
    , 1482 (D.C. Cir. 1996) (criminal defendant
    waived constitutional challenge under the Commerce Clause).
    In a civil case, Bahlul’s forfeiture would be fatal; we
    would not review his newly raised claims at all. See
    Nemariam v. Federal Democratic Republic of Ethiopia, 
    491 F.3d 470
    , 483 (D.C. Cir. 2007) (“[A]bsent exceptional
    circumstances, the court of appeals is not a forum in which a
    litigant can present legal theories that it neglected to raise in a
    9
    timely manner in proceedings below.”) (internal quotation
    marks omitted). Criminal cases, however, are different.
    Typically, when a criminal defendant forfeits a challenge,
    even a constitutional one, an appellate court will still review
    the claim for “plain error.” FED. R. CRIM. P. 52(b); see, e.g.,
    United States v. Cotton, 
    535 U.S. 625
    , 631–632 (2002). A
    forfeited error warrants reversal as “plain error” only if the
    error was “clear” or “obvious” at the time it was made.
    
    Olano, 507 U.S. at 734
    . Even then, the decision whether to
    correct the forfeited error lies “within the sound discretion of
    the court of appeals.” 
    Id. at 732.
    Courts should not exercise
    that discretion unless the error “seriously affect[ed] the
    fairness, integrity or public reputation of judicial
    proceedings.” United States v. Young, 
    470 U.S. 1
    , 15 (1985);
    see also FED. R. CRIM. P. 52(b) (“A plain error that affects
    substantial rights may be considered even though it was not
    brought to the court’s attention.”) (emphasis added).
    While my colleagues believe that the constitutional
    importance of the issues presented and their implications
    warrant a discretionary exercise of de novo review, see
    Wilkins Concurring Op. at 1; Joint Dissent at 4–9; see also
    Kavanaugh Concurring Op. at 3 n.1, limiting appellate review
    to plain errors when a criminal defendant fails to object at
    trial serves a vital function within the criminal justice system.
    The plain-error rule “induce[s] the timely raising of claims
    and objections,” which in turn affords the trial court the
    opportunity both “to determine the relevant facts and
    adjudicate the dispute” in the first instance and, if warranted,
    to “correct or avoid the mistake so that it cannot possibly
    affect the ultimate outcome.” 
    Puckett, 556 U.S. at 134
    .
    The contemporaneous-objection rule also prevents a
    defendant from “‘sandbagging’ the court—remaining silent
    about his objection and belatedly raising the error only if the
    10
    case does not conclude in his favor,” 
    Puckett, 556 U.S. at 134
    —which is exactly what Bahlul is doing.
    “[E]ncourag[ing] all trial participants” instead “to seek a fair
    and accurate trial the first time around” promotes fairness to
    the court, to all of the parties, 
    Frady, 456 U.S. at 163
    , and to
    the public, as well as stability in the law. See generally Exxon
    Shipping Co. v. Baker, 
    554 U.S. 471
    , 487 n.6 (2008)
    (“[W]aiver and forfeiture rules * * * ensure that parties can
    determine when an issue is out of the case, and that litigation
    remains, to the extent possible, an orderly progression.”).
    As our prior en banc opinion explained, Bahlul “flatly
    refused to participate in the military commission
    proceedings,” and to the extent that he objected at all to his
    trial, the objection “was couched entirely in political and
    religious terms.” Bahlul 
    I, 767 F.3d at 10
    ; see 
    id. at 7
    (“Bahlul waived all pretrial motions, asked no questions
    during voir dire, made no objections to prosecution evidence,
    presented no defense and declined to make opening and
    closing arguments.”).      Bahlul declared that he was a
    “prisoner[] of war and legal combatant[] based on [his]
    religion,” rejected the United States’ “earthly laws and
    international earthly laws,” questioned “how can there be a
    tribunal, a court, a complete court, and a fair court as long as
    they do not—when they do not accept our rules, our laws,”
    and then concluded that “there is going to be the tribunal of
    God on the day of judgments.” Pet. App. 109–112.
    That generic diatribe against the proceedings writ large
    did not preserve the specific constitutional challenges that
    Bahlul now presses. His complaints were far “too general to
    have alerted the trial court to the substance of [his] point,”
    United States v. Bolla, 
    346 F.3d 1148
    , 1152 (D.C. Cir. 2003)
    (Roberts, J.) (quotation marks omitted), or to have given the
    court or opposing counsel any notice of the constitutional
    11
    character of his claim, see also United States v. Love, 
    593 F.3d 1
    , 11 (D.C. Cir. 2010) (defendant’s “general objection
    * * * was insufficient to preserve his arguments for appeal”);
    United States v. Breedlove, 
    204 F.3d 267
    , 270 (D.C. Cir.
    2000) (an objection “couched in terms too general” to have
    put the trial court on notice of “the substance of the [claim]”
    was not preserved).
    To be sure, I do not believe a defendant must cite to any
    particular case or style arguments in a particular way to
    sufficiently preserve a claim. See United States v. Rashad,
    
    396 F.3d 398
    , 401 (D.C. Cir. 2005). All Bahlul had to do was
    “inform the court and opposing counsel of the ruling he
    want[ed] the court to make and the ground for so doing.” 
    Id. But Bahlul
    failed to do even that. He did not so much as
    mention the Constitution. He just categorically disdained the
    trial process. Accordingly, I would hold Bahlul to the same
    standard that courts apply every day to other criminal
    defendants who fail to preserve claims, and would review his
    new constitutional challenges only for plain error.
    B
    To evade the consequences of his forfeiture, Bahlul tries
    to package his Article III claim as a challenge to the military
    commission’s subject-matter jurisdiction, presumably because
    “defects in subject-matter jurisdiction require correction
    regardless of whether the error was raised” below. 
    Cotton, 535 U.S. at 630
    . That tactic fails. This Court has already
    held that the 2006 Act “explicitly confers jurisdiction on
    military commissions to try the charged offenses.” Bahlul 
    I, 767 F.3d at 10
    n.6. There thus should be no question that the
    military commission acted within its statutorily assigned
    jurisdiction.
    12
    What Bahlul’s challenge really goes to is whether, in
    authorizing a law-of-war military commission to decide the
    conspiracy charge, Congress exceeded its constitutional
    authority under either Article I’s Define and Punish Clause or
    Article III’s Judicial Power Clause. In general, if a suit falls
    within the judicial power, then “the responsibility for deciding
    that suit rests with Article III judges in Article III courts.”
    
    Stern, 564 U.S. at 484
    . But an exception exists for certain
    criminal prosecutions—specifically, criminal violations of the
    international laws of war—which constitutionally may be
    tried before military commissions.           See Johnson v.
    Eisentrager, 
    339 U.S. 763
    , 786 (1950) (“The jurisdiction of
    military authorities, during or following hostilities, to punish
    those guilty of offenses against the laws of war is long-
    established.”).
    Bahlul argues that his prosecution for conspiracy before
    the military commission did not fall within any such
    exception because it did not charge a violation of the
    international law of war. And because of that, Bahlul says, he
    was constitutionally entitled to have the charges against him
    brought before an Article III court.
    The problem for Bahlul’s effort to frame that argument
    as jurisdictional is that “[e]ven the unconstitutionality of the
    statute under which the proceeding is brought does not oust a
    court of jurisdiction.” United States v. Williams, 
    341 U.S. 58
    ,
    65 (1951). As long as the military commission “exercises its
    power under a presumptively valid federal statute, it acts
    within its subject-matter jurisdiction[.]” 
    Baucum, 80 F.3d at 540
    . Indeed, in this Court’s previous en banc decision, we
    reviewed another separation-of-powers claim pressed by
    Bahlul—his Ex Post Facto Clause claim—for plain error,
    even though that challenge concerned the constitutionality of
    the 2006 Act, and thus the power of the United States to
    13
    proceed against him. See Bahlul 
    I, 767 F.3d at 10
    & n.6; see
    also Carmell v. Texas, 
    529 U.S. 513
    , 531 n.21 (2000) (the Ex
    Post Facto Clause is in part “aimed at * * * reinforcing the
    separation of powers”).
    Bahlul’s claims here have no more jurisdictional aspect
    than did his ex post facto claims. His Define and Punish
    Clause argument is a challenge to the constitutionality of the
    2006 Act. So too is Bahlul’s Judicial Power Clause
    argument: “The ‘Article III’ label changes nothing; by this
    Clause, Article III restricts the Congress’s power, not the
    power of the courts or military commissions.” Bahlul v.
    United States (Bahlul II), 
    792 F.3d 1
    , 31 (D.C. Cir. 2015)
    (Henderson, J., dissenting). To hold otherwise would mean
    that “a court would be required to raise [a Judicial Power
    Clause challenge] sua sponte each time it reviews a decision
    of a non-Article III tribunal,” even if the parties do not contest
    that issue. 
    Id. at 32;
    see generally 
    Baucum, 80 F.3d at 541
    (Courts have “an obligation to address jurisdictional questions
    sua sponte.”).
    In short, Bahlul’s “belated assertion of a constitutional
    defect” does “not work to divest” the military commission of
    its jurisdiction to try him. 
    Baucum, 80 F.3d at 541
    .
    Accordingly, his constitutional challenge to Congress’s
    authorization of his conspiracy prosecution before a military
    commission should be subject to the same contemporaneous-
    objection requirement as any other constitutional claim.
    C
    1
    After that long preface, I arrive at the heart of Bahlul’s
    argument for de novo review: He contends that a criminal
    defendant can never forfeit an Article III structural claim.
    14
    Specifically, Bahlul argues that the Judicial Power Clause of
    Article III prohibits Congress from assigning the trial of
    criminal conspiracies to a non-Article III tribunal, and that
    such a structural Article III claim is not subject to plain-error
    review.
    For support, Bahlul points to the Supreme Court’s
    decision in Commodity Futures Trading Commission v.
    Schor, 
    478 U.S. 833
    (1986). In that case, Schor challenged
    the Commodity Futures Trading Commission’s jurisdiction
    over certain common-law counterclaims in civil reparations
    proceedings. Schor argued that Article III required that those
    traditionally common-law claims be decided by the Judicial
    Branch, not by an Executive Branch tribunal. 
    Id. at 835–836.
    While acknowledging that “Schor indisputably waived any
    right he may have possessed [by] expressly demand[ing] that
    [the other party] proceed on its counterclaim” before the
    Commission, the Supreme Court addressed the merits of his
    structural challenge de novo. 
    Id. at 849–851.
    In so doing, the
    Supreme Court explained that “Article III, § 1 safeguards the
    role of the Judicial Branch in our tripartite system by barring
    congressional attempts to transfer jurisdiction to non-Article
    III tribunals for the purpose of emasculating constitutional
    courts[.]” 
    Id. at 850
    (quotation marks omitted, alterations in
    original). When that “structural principle is implicated in a
    given case,” the Court added, traditional rules “of consent and
    waiver cannot be dispositive” because those Article III
    limitations “serve institutional interests that the parties cannot
    be expected to protect.” 
    Id. at 850
    –851 (quotation marks,
    citations, and alterations omitted); see also Freytag v.
    Commissioner of Internal Revenue, 
    501 U.S. 868
    , 880 (1991)
    (“Neither Congress nor the Executive can agree to waive
    * * * structural protection[s].”); Wellness Int’l Network, Ltd.
    v. Sharif, 
    135 S. Ct. 1932
    , 1945 n.10 (2015) (“What Schor
    15
    forbids is using consent to excuse an actual violation of
    Article III.”).
    Bahlul takes those passages to mean that an Article III
    structural claim can never be forfeited, and that we are thus
    obligated to review his claim de novo. That overreads Schor.
    What the Supreme Court said is that “notions of consent and
    waiver cannot be dispositive.” 
    Schor, 478 U.S. at 851
    (emphasis added). At most, that means that appellate courts
    have discretion to hear unpreserved Article III structural
    claims de novo in appropriate cases, not that they are
    obligated to do so. Subsequent Supreme Court precedent
    proves that point.
    To begin with, in Plaut v. Spendthrift Farm, Inc., 
    514 U.S. 211
    (1995), the Supreme Court held that the Securities
    Exchange Act’s requirement that federal courts reopen certain
    final judgments in private civil actions violated Article III
    because the Article III judicial power is the power to decide
    cases conclusively. 
    Id. at 213,
    218. The government had
    invoked Schor’s non-waiver language in defense of the
    statute, reasoning that if the finality of federal court
    judgments implicated Article III, then res judicata would not
    be waivable either. 
    Id. at 231.
    The Supreme Court gave no
    quarter to that reading of Schor: “The proposition that legal
    defenses based upon doctrines central to the courts’ structural
    independence can never be waived simply does not accord
    with our cases.” 
    Id. What Schor
    meant, the Supreme Court
    explained, was that a court could still “choose to consider his
    Article III challenge,” notwithstanding a litigant’s consent to
    an alternative tribunal, because when “‘Article III limitations
    are at issue, notions of consent and waiver cannot be
    dispositive[.]’” 
    Id. at 232
    (first emphasis added; quoting
    
    Schor, 478 U.S. at 851
    ).
    16
    The Supreme Court reconfirmed twice just two Terms
    ago that courts may treat Article III structural claims as
    subject to waiver and forfeiture. In B&B Hardware, Inc. v.
    Hargis Industries, Inc., 
    135 S. Ct. 1293
    (2015), the Court held
    that a decision by the Trademark Trial and Appeal Board—a
    non-Article III tribunal—is entitled to the same preclusive
    effect as a district court decision if the ordinary elements of
    issue preclusion are met, 
    id. at 1299.
    In so holding, the Court
    eschewed consideration of any potentially “meritorious
    constitutional objection” under Article III because that
    argument was abandoned by Hargis Industries, and thus “it is
    not before us.” 
    Id. at 1304
    (citing 
    Plaut, 514 U.S. at 231
    –
    232).
    Continuing that pattern, in Wellness International
    
    Network, supra
    , the Court held that “Article III is not violated
    when the parties knowingly and voluntarily consent to
    adjudication by a bankruptcy judge” of a state-law claim that
    arose independently of bankruptcy 
    law, 135 S. Ct. at 1939
    . In
    Stern v. 
    Marshall, supra
    , the Court had held that, as a general
    matter, Article III forbids bankruptcy courts to enter final
    judgments on such 
    claims, 564 U.S. at 500
    –501. Wellness,
    however, created an exception to that general rule where both
    parties consent to bankruptcy-court adjudication.
    Critically, at the end of its Wellness opinion, the Supreme
    Court remanded the case to the Seventh Circuit to decide
    whether Sharif’s consent was knowing and voluntary, and
    whether “Sharif forfeited his Stern argument below.” 135 S.
    Ct. at 1949. That remand would, of course, have been
    pointless if Article III structural claims like the Stern claim
    can never be waived or forfeited. See also 
    Sharif, 135 S. Ct. at 1949
    (Alito, J., concurring in part and concurring in the
    judgment) (“[R]espondent forfeited any Stern objection by
    failing to present that argument properly in the courts below.
    17
    Stern vindicates Article III, but that does not mean that Stern
    arguments are exempt from ordinary principles of appellate
    procedure.”).
    Of course, as the panel majority and concurrence well
    chronicled, the Supreme Court’s pronouncements in this area
    have been far from crystalline. See Bahlul 
    II, 792 F.3d at 3
    –
    5; 23–24 (Tatel, J., concurring). But B&B Hardware and
    Wellness have done much to lift the fog. I accordingly
    conclude that Schor does not require us to wade into a
    constitutional thicket and review de novo Bahlul’s forfeited
    Article III structural challenge.
    2
    I agree with my colleagues, however, that Schor affords
    this Court some discretion to review a forfeited Article III
    claim de novo. See Kavanaugh Concurring Op. at 3 n.1, Joint
    Dissent at 4-6. But I would decline to exercise that discretion
    in this case for three reasons.
    First, there is no structural reason to take up Bahlul’s
    fight with the Political Branches. Unlike Schor, Freytag,
    Stern, Plaut, B&B Hardware, and Wellness, which were all
    civil cases, this is a criminal case. That distinction matters
    because the consequences of forfeiture are materially different
    in civil and criminal contexts. In civil cases, a claim that a
    party waives or forfeits is generally gone for good. An
    appellate court will not review it under any standard of
    review. See Salazar ex rel. Salazar v. District of Columbia,
    
    602 F.3d 431
    , 437 (D.C. Cir. 2010); 
    Nemariam, 491 F.3d at 482
    –483; cf. Singleton v. Wulff, 
    428 U.S. 106
    , 121 (1976)
    (noting rare “circumstances in which a federal appellate court
    is justified in resolving an issue not passed on below, as
    where the proper resolution is beyond any doubt * * * or
    where injustice might otherwise result”).
    18
    In addition, civil cases can pose the risk of parties
    colluding and consenting to a non-Article III forum for
    resolution of their dispute. Absent discretionary review, such
    joint waivers of challenges to the judicial forum could
    effectively strip Article III courts of the ability ever to address
    the constitutionality of legislation reassigning the judicial
    power.
    That perceived need to ensure some mechanism for
    enforcing the separation of powers and protecting the judicial
    power against incursions by the Political Branches seemingly
    motivated Schor’s discretionary exception to traditional
    principles of waiver and forfeiture in civil cases. As the
    Supreme Court explained, Article III “limitations serve
    institutional interests that the parties cannot be expected to
    protect.” 
    Schor, 478 U.S. at 851
    ; see also Peretz v. United
    States, 
    501 U.S. 923
    , 950 (1991) (“Article III serves as an
    inseparable element of the constitutional system of checks and
    balances by preserving the role of the Judicial Branch in our
    tripartite system of government.”) (quotation marks omitted).
    Unlike civil cases, however, criminal cases like Bahlul’s
    present no similar need to work around the ordinary
    contemporaneous-objection rule. The whole reason my
    colleagues and I are even debating the application of the
    “plain-error” standard of review is that, in criminal cases,
    forfeited claims are not really forfeited at all. They are still
    subject to judicial review and decision; all that changes is the
    level of scrutiny. See FED. R. CIV. P. 52(b); 
    Olano, 507 U.S. at 733
    –735. In other words, in criminal cases, a “forfeited”
    Article III claim is still reviewed and decided; it is just harder
    to win. See, e.g., 
    Olano, 507 U.S. at 734
    (“A court of appeals
    cannot correct an error pursuant to Rule 52(b) unless the error
    is clear under current law.”); In re Sealed Case, 
    573 F.3d 844
    ,
    851 (D.C. Cir. 2009) (“[A]n error can be plain if it violates an
    19
    absolutely clear legal norm.”) (quotation marks omitted).
    That means that, unlike civil cases, the availability of plain-
    error review in criminal cases ensures that clear or obvious
    usurpations of Article III will not escape judicial scrutiny,
    regardless of whether a criminal defendant timely raised such
    objections below.
    Likewise, even when a criminal defendant affirmatively
    waives (rather than forfeits) a structural Article III challenge,
    the argument may, if warranted, still be reviewed later
    through the lens of an ineffective-assistance-of-counsel claim.
    If the constitutional transgression is so clear that a failure to
    raise it was not “within the range of competence demanded of
    attorneys in criminal cases,” and if it prejudiced the
    defendant’s case, see United States v. Streater, 
    70 F.3d 1314
    ,
    1318 (D.C. Cir. 1995) (quoting Hill v. Lockhart, 
    474 U.S. 52
    ,
    56, 59 (1985)), an appellate court may decide the
    constitutional question. 3
    3
    In a series of cases challenging the Federal Magistrates Act, Pub.
    L. No. 90-578, 82 Stat. 1107–1119 (1968), the Supreme Court
    addressed constitutional objections to adjudications by non-Article
    III federal magistrate judges in criminal cases. However, none of
    those cases presented a structural Article III question because the
    district court’s de novo review ensured that the operative decision
    was made by an Article III judge. See, e.g., 
    Peretz, 501 U.S. at 937
    (“[N]o * * * structural protections are implicated” because “[t]he
    ultimate decision whether to invoke the magistrate’s assistance is
    made by the district court, subject to veto by the parties.”)
    (quotation omitted); United States v. Raddatz, 
    447 U.S. 667
    , 683
    (1980) (The “delegation does not violate Art. III so long as the
    ultimate decision is made by the district court.”); see also Gomez v.
    United States, 
    490 U.S. 858
    , 874 (1989) (construing the Act not to
    authorize magistrate judges to supervise jury selection in part
    because the court “harbor[ed] serious doubts that a district judge
    could review this function meaningfully”).
    20
    Second, in almost all of the Supreme Court cases granting
    review of a structural Article III question, the barrier to
    judicial review was waiver, not forfeiture. See 
    Wellness, 135 S. Ct. at 1939
    (noting “the parties’ consent” to bankruptcy
    court adjudication); 
    Freytag, 501 U.S. at 878
    (“[P]etitioners
    gave their consent to trial before the Special Trial Judge.”);
    
    Schor, 478 U.S. at 837
    (Schor himself “invoked the
    [Commission’s] reparations jurisdiction[.]”). The waivers
    arose, moreover, because Congress designed the challenged
    statutory schemes so that litigants would first choose to bring
    their claim in a non-Article III forum. In that way, Congress
    baked the barrier to judicial review right into the allegedly
    Article III-circumventing statutory scheme, thus presenting
    the question whether Congress could team up with litigants to
    divert the judicial power to a non-Article III tribunal. See
    
    Wellness, 135 S. Ct. at 1939
    (considering “whether Article III
    allows bankruptcy judges to adjudicate [Stern] claims with the
    parties’ consent”); 
    Schor, 478 U.S. at 851
    (“[T]he parties
    cannot by consent cure the constitutional difficulty.”).
    By definition, the constitutionality of such statutory
    schemes could not be determined without bypassing the
    element of private choice that Congress used to trigger the
    non-Article III tribunal in the first instance. That presumably
    is why the Supreme Court explained in Plaut that “[w]aiver
    subject to the control of the courts themselves”—rather than
    imposed by Congress—would be materially different to the
    constitutional analysis, “would obviously raise no issue of
    separation of powers, and would be precisely in accord with”
    Schor. 
    Plaut, 514 U.S. at 231
    –232 (emphasis added).
    This case, however, involves a forfeiture, not a waiver, of
    an Article III objection that was fully available to Bahlul
    throughout the military commission proceeding. Bahlul, like
    criminal defendants generally, had every opportunity and
    21
    incentive to raise objections that (if successful) would have
    foreclosed his conviction or would have provided grounds for
    a full reversal on appeal. Indeed, criminal defendants as a
    class are profoundly self-interested when it comes to
    preserving substantial legal challenges to exercises of
    prosecutorial power. Thus the risk that criminal defendants
    will team up with the prosecution in a way that would
    otherwise preclude judicial enforcement of the separation of
    powers is something short of negligible.
    For those reasons, the contemporaneous-objection rule
    does not pose the same practical barrier to constitutional
    review in criminal cases that it did in Schor’s civil litigation
    context. Instead, in criminal prosecutions, “the claims of
    individuals * * * have been the principal source of judicial
    decisions concerning separation of powers and checks and
    balances.” Bond v. United States, 
    564 U.S. 211
    , 222 (2011).
    Here as well, all that would be needed for a court to decide de
    novo the structural Article III question that Bahlul belatedly
    raises is for a defendant in one of the other pending military
    commission proceedings to timely raise it as a defense to
    prosecution in that forum.
    Third, Bahlul has identified no unusual obstacles or
    exceptional circumstances that excuse his failure to raise his
    Article III claim before the military commission. He had the
    benefit of trained counsel and multiple procedural
    opportunities to voice his constitutional objections. Bahlul’s
    knowing and willful refusal to participate in his trial should
    not now be rewarded by addressing his constitutional
    arguments de novo rather than under plain-error review. To
    the contrary, excusing Bahlul’s failure to bring his Article III
    structural claim would encourage similar sandbagging
    behavior from other military commission defendants. They
    would have nothing to lose by first trying their chances before
    22
    the commission and, if unhappy with the results, pulling an
    Article III challenge out of their pocket in the hope of trying
    the case all over again in federal court (with the added benefit
    of the prosecution’s hand having been revealed).
    Bahlul argues (Pet. Br. 37), and Judge Kavanaugh’s
    concurring opinion agrees (at 3 n.1), that the government
    failed to raise any forfeiture argument before the Court of
    Military Commission Review, or to argue for plain-error
    review, and thus it “has—in a word—forfeited [its] forfeiture
    argument here,” Pet. Br. 37 (quoting Solomon v. Vilsack, 
    763 F.3d 1
    , 13 (D.C. Cir. 2014)); see also Joint Dissent at 2–4. I
    read our precedent and the record differently.
    For starters, the rule that a party may forfeit a forfeiture
    argument applies to the preservation of a substantive legal
    claim in a civil case, like the discriminatory retaliation claim
    that was at issue in 
    Solomon, 763 F.3d at 13
    . The issue in this
    criminal appeal, however, is not whether Bahlul’s
    constitutional claims get reviewed at all—the special plain-
    error rule in criminal cases ensures some type of review. The
    only question is which standard of review governs the appeal,
    and “[t]he Government cannot alter our standard of review—
    by concession, inadvertence, poor oral advocacy or
    otherwise.” Bahlul 
    II, 792 F.3d at 3
    2 n.3 (Henderson, J.,
    dissenting); see United States v. Nueci-Pena, 
    711 F.3d 191
    ,
    196 n.5 (D.C. Cir. 2013) (reviewing for plain error although
    the government “erroneously assert[ed] that de novo review
    applie[d]”). That is because, as an appellate court, this court
    “must apply some standard of review to every issue it
    considers * * * [so] no party has the power to control our
    standard of review.” United States v. Vontsteen, 
    950 F.2d 1086
    , 1091 (5th Cir. 1992) (emphasis omitted).
    23
    Said another way, standards of review are not claims that
    parties can choose to make or not in a case. Those review
    standards instead enforce structural judgments about the
    relative expertise of trial and appellate courts, and the need
    for efficiency, fairness, and stability in the judicial process.
    See 
    Puckett, 556 U.S. at 134
    . To illustrate, trial courts bear
    primary responsibility for fact-finding because they see the
    evidence and witnesses firsthand, and superintend evidentiary
    rules and the creation of the record in the case. An appellate
    court reviewing only the paper record is ill-positioned to
    make factual findings, and so we review factual
    determinations only for clear error. See Anderson v. City of
    Bessemer City, N.C., 
    470 U.S. 564
    , 574 (1985); United States
    v. United States Gypsum Co., 
    333 U.S. 364
    , 395 (1948). We
    would not find facts de novo if a party failed to argue for—or
    even agreed to waive—clear-error review.
    Plain-error review likewise enforces structural interests
    by ensuring that (i) potential errors can be stopped before
    harm occurs and resources are invested in a trial that must be
    redone; (ii) trial court determinations are not ambushed on
    appeal by never-before-voiced objections; and (iii) the
    number of reversals is reduced, which promotes trust in the
    stability of court judgments and finality in the enforcement of
    criminal law. See 
    Puckett, 556 U.S. at 134
    ; see also United
    States v. Hunter, 
    786 F.3d 1006
    , 1111 (D.C. Cir. 2015) (The
    contemporaneous-objection rule’s goal of timely rectifying
    errors “is not served when a defendant raises an objection
    after proceedings are complete and a ruling has been handed
    down.”).
    On top of that, the record shows that the government did
    not forfeit its forfeiture argument. Before the Court of
    Military Commission Review, the government specifically
    argued that Bahlul “waived all motions, defenses or
    24
    objections (except for lack of jurisdiction or failure to allege
    an offense) when he failed to raise any issues below.” Pet.
    App. 161. Indeed, this court’s prior en banc decision
    acknowledged that the government “argued for plain-error
    review before the [Court of Military Commission Review], in
    its original brief to the panel of this Court and in its brief to
    the en banc court.” Bahlul 
    I, 767 F.3d at 10
    n.5; see also
    Brief for the United States at 65, Bahlul v. United States, 
    2013 WL 297726
    (D.C. Cir. Jan. 25, 2013) (arguing that Bahlul’s
    Define and Punish Clause, Ex Post Facto Clause, and Article
    III arguments “were forfeited below”).
    To be sure, at oral argument before the panel, the
    government suggested that Bahlul’s structural argument might
    not be forfeitable, see Pet. Supp. App. 234. But immediately
    thereafter, counsel asserted that “[t]he structural component of
    that argument is forfeitable,” 
    id. at 235
    (emphasis added). In
    addition, the government argued that Bahlul had not raised an
    Article III structural claim at all. See 
    id. at 234
    (“I do not
    acknowledge that he was raising [a structural Article III
    argument].”). In my view, that is far too murky a foundation
    from which to launch this court into applying an unwarranted
    standard of review to adjudge the constitutionality of a joint
    exercise by the President and the Congress of their national
    security and war powers. See, e.g., Youngstown Sheet & Tube
    Co. v. Sawyer, 
    343 U.S. 579
    , 637 (1952) (Jackson, J.,
    concurring) (joint exercises of power by the Political
    Branches merit “the widest latitude of judicial
    interpretation”); see also Bank Markazi v. Peterson, 136 S.
    Ct. 1310, 1328 (2016) (“[F]oreign affairs” is “a domain in
    which the controlling role of the political branches is both
    necessary and proper.”); Center for National Security Studies
    v. United States Dep’t of Justice, 
    331 F.3d 918
    , 927 (D.C. Cir.
    2003) (“[T]he judiciary owes some measure of deference to
    the executive in cases implicating national security[.]”).
    25
    Nor do I understand why labeling Bahlul’s argument as
    “structural” should change the rules. The Constitution at
    every turn divides power not only horizontally between the
    federal branches of government, but also vertically between
    the national government, the States, and individuals. It is
    hard to understand why Bahlul’s Article III claim is any more
    structural than Bahlul’s Ex Post Facto claim, to which this
    court sitting en banc accorded only plain-error review. See
    also 
    Carmell, 529 U.S. at 531
    n.21 (Ex Post Facto Clause is
    in part “aimed at * * * reinforcing the separation of powers”).
    The dissenting opinion adds that courts have a “strong
    interest * * * in maintaining the constitutional plan of
    separation of powers.” Joint Dissent at 9 (quoting Glidden
    Co. v. Zdanok, 
    370 U.S. 530
    , 536 (1962)). True. But when
    the only reason a separation-of-powers claim is not teed up is
    because the defendant chose not to raise it below, courts
    routinely apply plain-error review. See, e.g., United States v.
    Gonzalez, 
    682 F.3d 201
    , 203 (2d Cir. 2012) (reviewing
    separation-of-powers claim for plain error “because [the
    defendant] did not raise the issue[] below”); United States v.
    Anderson, 
    591 F.3d 789
    , 792 (5th Cir. 2009) (reviewing for
    plain error where the defendant “could have mentioned
    separation of powers [below] but, for whatever reason, he
    chose not to”). 4
    The dissenting opinion also suggests that this really-
    important-issue exception can be limited to intrusions on the
    judiciary’s Article III turf because then the court is granting
    de novo review for the courts’ “own benefit,” to “protect the
    4
    See also, e.g., United States v. Clark, 
    634 F.3d 874
    , 877 (6th Cir.
    2011); United States v. Carraway, 
    612 F.3d 642
    , 646 (7th Cir.
    2010); United States v. Evans, 
    587 F.3d 667
    , 671 (5th Cir. 2009);
    United States v. Rusan, 
    460 F.3d 989
    , 992 (8th Cir. 2006); United
    States v. Pojilenko, 
    416 F.3d 243
    , 249 n.6 (3d Cir. 2005).
    26
    judiciary’s role within our system of divided government,”
    Joint Dissent at 9, 6. But the Constitution separates power to
    protect the rights and liberty of the people, not to protect the
    courts for the courts’ sake. See New York v. United States,
    
    505 U.S. 144
    , 182 (1992) (“T]he constitution divides
    authority * * * for the protection of individuals. * * * The
    Constitution’s division of power among the three branches is
    violated where one branch invades the territory of another,
    whether or not the encroached-upon branch approves the
    encroachment.”). Plus it seems to me wholly untenable for
    courts to decide that one criminal defendant’s Eighth
    Amendment challenge to his death sentence fails on plain-
    error review, see, e.g., United States v. McGarity, 
    669 F.3d 1218
    , 1255 (8th Cir. 2012), but an enemy combatant’s
    challenge to his capital conviction succeeds because it was to
    the court’s “own benefit” to afford it plenary review.
    Whatever considerations may appropriately weigh in favor of
    a discretionary decision to grant de novo review, the
    dispositive factor in a criminal case should not be that the
    federal judiciary decides it has skin in the game.
    Judge Kavanaugh’s concurring opinion concludes that
    the “extraordinary importance” of the constitutional questions
    is a reason to excuse Bahlul from the consequences of his
    forfeiture and grant de novo review. Kavanaugh Concurring
    Op. at 3 n.1. I think that gets the constitutional calculus
    exactly backwards. The separation of powers should counsel
    the greatest judicial hesitation when the Political Branches are
    jointly exercising their judgment in areas of national security,
    the conduct of war, and foreign relations. See generally
    Youngstown Sheet & Tube 
    Co., 343 U.S. at 636
    –637 (joint
    actions of the Political Branches “personify the federal
    sovereignty” and “would be supported by the strongest of
    presumptions and the widest latitude of judicial
    interpretation”). Here the constitutional structure itself raises
    27
    a yellow caution flag against unnecessary judicial intrusion,
    making it the better judicial course just to decide “the
    narrower ground for adjudication of the constitutional
    questions in [a] case * * * first.” 
    Plaut, 514 U.S. at 217
    .
    Here, that means applying plain-error review.
    III
    To prevail on plain-error review, Bahlul must show that
    the alleged error (i) is plain, (ii) affected his substantial rights,
    and (iii) seriously affected the fairness, integrity or public
    reputation of judicial proceedings. See 
    Olano, 507 U.S. at 732
    –737. For an error to be “plain,” it must be “clear” or
    “obvious.” 
    Id. at 734.
    “A ruling’s error is clear if, at the time
    it was made, a clear precedent in the Supreme Court or this
    circuit established its erroneous character.” United States v.
    Terrell, 
    696 F.3d 1257
    , 1260 (D.C. Cir. 2012).
    “Meeting all four prongs” of the plain-error test “is
    difficult, as it should be.” 
    Puckett, 556 U.S. at 135
    (quotation
    marks omitted). Doubly so here because the Supreme Court
    has instructed that the actions of a military commission “are
    not to be set aside by the courts without the clear conviction
    that they are in conflict with the Constitution or laws of
    Congress constitutionally enacted.” 
    Quirin, 317 U.S. at 2
    .
    Bahlul’s constitutional claims cannot survive that demanding
    review. 5
    5
    The Supreme Court explained in Hamdan v. Rumsfeld, 
    548 U.S. 557
    (2006), that “the precedent” supporting trial by military
    commission “must be plain and unambiguous” in those instances
    “[w]hen * * * neither the elements of the offense nor the range of
    permissible punishments is defined by statute or treaty,” 
    id. at 602.
    That standard does not apply here because the 2006 Act specifically
    defines the elements of its conspiracy provision and identifies it as
    28
    Bahlul’s principal argument is that, in authorizing his
    prosecution before a military commission for what he labels
    “inchoate conspiracy,” Congress exceeded its legislative
    power under the Define and Punish Clause, U.S. CONST., Art.
    I, § 8, cl. 10. Specifically, Bahlul argues that the conspiracy
    for which he was charged and convicted cannot be an
    “Offence[] against the Law of Nations,” within the meaning
    of Article I of the Constitution, because inchoate conspiracy is
    not a recognized crime under international law. Bahlul
    further argues that inchoate conspiracy, as a stand-alone
    offense, was traditionally triable by jury at common law and
    for that reason falls exclusively within the Article III judicial
    power.
    Because Bahlul presses only an as-applied challenge to
    his own conviction under the 2006 Act, see Oral Arg. Tr. 6;
    Pet. Br. 57, I would not decide whether Congress has the
    constitutional power to authorize the prosecution generally of
    inchoate conspiracies before a military commission. Rather,
    for five reasons, it is neither clear nor obvious—in other
    words, it is not plain—that the particular statutory conspiracy
    of which Bahlul was convicted must be tried in an Article III
    court.
    First, in arguing that Congress lacked the legislative
    authority to assign his conspiracy charge to a military
    commission for trial, Bahlul places great weight on the
    government’s concession that inchoate conspiracy has not yet
    been recognized as an offense against international law. Pet.
    Br. 16; see Brief for the United States at 50, Bahlul v. United
    States, 
    2013 WL 297726
    (D.C. Cir. Jan. 25, 2013). But “we
    are not obligated to accept the Government’s concession.”
    an offense triable by military commission.           10 U.S.C.
    § 950v(b)(28).
    29
    Bahlul 
    I, 757 F.3d at 18
    ; see also United States v. Baldwin,
    
    563 F.3d 490
    , 491 (D.C. Cir. 2009) (“We are not obligated to
    accept the government’s confession of error, particularly
    when there is reason to doubt whether the government’s
    position is correct.”) (citation omitted). That is because “the
    separation of powers does not depend on the views of
    individual Presidents, nor on whether the encroached-upon
    branch approves the encroachment.” Free Enterprise Fund v.
    Public Company Accounting Oversight Bd., 
    561 U.S. 477
    ,
    497 (2010) (citation and quotation marks omitted). More to
    the point, plain-error analysis looks at how clearly established
    governing law is, not the briefing strategies of particular
    parties.
    Second, Bahlul’s asserted error—Congress’s power to
    criminalize traditional inchoate conspiracy in military
    commission proceedings—is not in fact implicated by his
    case. I agree with Judge Wilkins that the statutory conspiracy
    of which Bahlul was convicted goes beyond the elements of
    ordinary inchoate conspiracy. Traditionally, a conviction for
    inchoate conspiracy requires proof of only two elements:
    agreement between two or more persons, and intent thereby to
    achieve a certain objective. Wayne R. LaFave, Substantive
    Criminal Law § 12.2 (2015). Proof of neither an overt act nor
    a completed offense is required. See United States v.
    Shabani, 
    513 U.S. 10
    , 13–14 (1994) (“We have consistently
    held that the common law understanding of conspiracy ‘does
    not make the doing of any act other than the act of conspiring
    a condition of liability.’”) (quoting Nash v. United States, 
    229 U.S. 373
    , 378 (1913)). Moreover, an inchoate conspiracy
    could be tied to any object offense. Hogan v. O’Neill, 
    255 U.S. 52
    , 55 (1921).
    Conspiracy under the 2006 Act is materially different.
    To begin with, in addition to requiring a specific intent to
    30
    commit the overt acts, the 2006 Act also requires that the
    overt acts be committed with the intent “to effect the object of
    the conspiracy.” 10 U.S.C. § 950v(b)(28); see Pet. Supp.
    App. 137. Moreover, the only allowable objects of Bahlul’s
    conspiracy are “substantive offenses triable by military
    commission under” the Act. 10 U.S.C. § 950v(b)(28).
    Bahlul does not dispute that those substantive offenses
    include offenses against the law of war that may be tried
    before a military commission. On top of that, the statutory
    scheme seems to anticipate that a conviction will be linked to
    a completed offense. That is because the statute specifically
    ties the authorized sentences to the fate of the victims: the
    crime “shall be punished, if death results to one or more of the
    victims, by death or such other punishment as a military
    commission under this chapter may direct, and, if death does
    not result to any of the victims, by such punishment, other
    than death, as a military commission under this chapter may
    direct.” 
    Id. In compliance
    with the statute, Bahlul was found to have
    committed ten overt acts, including, for example, preparing a
    recruiting video celebrating the USS Cole attack, acting as bin
    Laden’s personal secretary, and preparing martyr wills for
    two of the 9/11 hijackers. He was also found guilty of
    conspiracy to commit seven charged objects, including
    murder of protected persons, attacking civilians, murder in
    violation of the law of war, and terrorism.
    Importantly, the military judge’s instructions to the
    commission enforced those distinct features of statutory
    conspiracy. The instructions expressly predicated Bahlul’s
    conviction on a finding “beyond a reasonable doubt” that
    Bahlul “personally committed at least one of the overt acts”
    charged. Pet. Supp. App. 140–141. In addition, for each
    object offense of the conspiracy, the commission was required
    31
    to “find beyond a reasonable doubt” that Bahlul (i) “entered
    into an agreement” to commit the offense; (ii) did so
    “intentionally”; (iii) “knew the unlawful purpose of the
    agreement”; (iv) “joined with the intent to further its unlawful
    purpose”; and (v) “committed an overt act in furtherance of
    the agreement.” 
    Id. at 145.
    The instructions emphasized that
    the government must “prove[] beyond a reasonable doubt that
    the agreement intended every element of” any offense that
    was determined to be an object of the conspiracy. 
    Id. at 140.
    Along with its guilty verdict, the commission returned
    detailed factual findings documenting its determination that
    Bahlul’s conspiracy met those statutory elements. The
    commission found that Bahlul committed ten of the charged
    overt acts, and entered into an agreement that “intended every
    element” of all seven alleged object offenses, Pet. Supp. App.
    140, including specifically “[m]urder of protected persons,”
    “attacking civilians,” “murder in violation of the law of war,”
    and “terrorism,” 
    id. at 137,
    each of which violates Article 3 of
    the Geneva Convention, see Geneva Convention (IV) Relative
    to the Treatment of Prisoners of War art. 3, Aug. 12, 1949, 75
    U.N.T.S. 2876 U.S.T. 3516.
    Thus, for all of Bahlul’s arguments about Congress’s
    power to convict him by military commission of traditional or
    common-law inchoate conspiracy, the commission convicted
    him of a different and distinct statutory conspiracy offense, in
    which Bahlul (i) knew the objects of the conspiracy, which
    included multiple violations of the international law of war;
    (ii) joined an agreement to intentionally further those
    violations of the law of nations; (iii) personally intended to
    have every element of those international law of war offenses
    committed; and (iv) intentionally undertook the overt acts to
    further the agreement’s unlawful purposes. Bahlul’s use of
    the common law as a constitutional yardstick thus overlooks
    32
    the elements of the statutory offense of which he was actually
    convicted and the dearth of precedent suggesting that
    substantive offenses against the international law of war were
    traditionally tried in courts at common law. Accordingly,
    whatever the scope of congressional authority to consign
    other stand-alone conspiracy offenses to a non-Article III
    tribunal, it is not plain that conspiracy to commit international
    war crimes as carefully defined in the 2006 Act falls
    exclusively within the Article III judicial power.
    Third, given the specific elements of Bahlul’s conspiracy
    conviction, any delta between his conspiracy offense and
    those offenses that international law proscribes is too narrow
    to rise to the level of plain constitutional error.
    To begin with, international law has recognized
    conspiracy as a stand-alone offense for certain illegal acts that
    bear a close resemblance to Bahlul’s charged conduct. For
    example, international law has long allowed prosecution for
    conspiracy to wage aggressive war (also known as common
    plan to wage aggressive war). See 1 TRIAL OF THE MAJOR
    WAR CRIMINALS BEFORE THE INTERNATIONAL MILITARY
    TRIBUNAL: NUREMBERG, 14 November 1945–1 October
    1946, p. 225 (1947). In that respect, international law
    recognizes that “[p]lanning and preparation are essential to
    the making of war,” and “[c]ontinued planning, with
    aggressive war as the objective” may be punished as a
    violation of the law of war. 
    Id. at 224–225;
    see also Hamdan
    v. Rumsfeld, 
    548 U.S. 557
    , 610 (2006) (plurality opinion)
    (describing “common plan to wage aggressive war” as “a
    crime against the peace [that] requires for its commission
    actual participation in a ‘concrete plan to wage war’”)
    (quoting 1 TRIAL OF MAJOR WAR 
    CRIMINALS, supra, at 225
    ).
    33
    Like Bahlul’s conviction, conspiracy to commit
    aggressive war at Nuremberg turned on the commission of
    overt acts directly tied to waging aggressive war and an object
    offense that was itself a crime against international law.
    Nothing in constitutional text or settled precedent plainly
    foreclosed Congress from bridging the gap between the
    formal waging of such war by officials of Nazi Germany and
    al Qaeda’s waging of terrorist aggression against the United
    States.
    Modern statutes defining international law offenses also
    permit punishment for conspiracy to commit genocide as a
    stand-alone offense. See Updated Statute of the International
    Criminal Tribunal for the Former Yugoslavia Art. 4 (2009)
    (ICTY Statute); Statute of the International Tribunal for
    Rwanda Art. 2 (1994); Convention on the Prevention and
    Punishment of the Crime of Genocide Art. 3, Dec. 9, 1948, 78
    U.N.T.S. 277. The Statute of the International Tribunal for
    the Former Yugoslavia, for example, expressly recognizes
    “conspiracy to commit genocide.” 
    Id., Art. 4.
    The statute
    defines genocide as, inter alia, “killing members of [a]
    group,” “causing serious bodily or mental harm to members
    of [a] group,” or “deliberately inflicting on the group
    conditions of life calculated to bring about its physical
    destruction in whole or in part,” “with intent to destroy, in
    whole or in part, [that] national, ethnical, racial or religious
    group[.]” 
    Id., Art. 4(2)(a);
    see Simon v. Republic of Hungary,
    
    812 F.3d 127
    , 143 (D.C. Cir. 2016) (similar, citing the
    Convention on the Prevention of the Crime of Genocide).
    Of course, the object offenses tied to Bahlul’s conviction
    do not include genocide. But Bahlul’s overt acts do include
    attempts to kill and cause serious bodily and mental harm on
    members of a specific group at least in part because of their
    protected characteristics. Bahlul’s video celebrating the USS
    34
    Cole attack calls for jihad against the United States and
    blames “Western infidels” for Muslim suffering. Bahlul 
    I, 767 F.3d at 5
    –6. Bahlul’s video has been translated into
    several languages and widely distributed. 
    Id. at 6.
    Given that
    international law proscribes a calculated conspiracy to
    exterminate individuals on the basis of their nationality
    (outside the context of formal war), constitutional law does
    not plainly foreclose Congress from using its Define and
    Punish Clause authority to outlaw a conspiracy to
    intentionally commit mass murder of and to incite acts of
    violence against Americans, at least when combined with an
    overt act furthering an object offence that violates
    international law.
    On top of that, international law recognizes some
    conspiracy offenses as an independent source of criminal
    liability. In particular, international law permits conviction
    for joint criminal enterprise where “a plurality of persons
    participat[es] in the criminal plan”; there is “a common
    purpose which amounts to or involves the commission of a
    crime”; and “the accused[] participat[es] in the common
    design.” Guilia Bigi, Joint Criminal Enterprise in the
    Jurisprudence of the International Criminal Tribunal for the
    Former Yugoslavia and the Prosecution of Senior Political
    and Military Leaders, in 14 MAX PLANCK YEARBOOK OF
    UNITED NATIONS LAW 56 (2010). The Rome Statute, for
    example, makes a person “criminally responsible and liable
    for punishment for a crime” if that person “contributes to the
    commission or attempted commission of such a crime by a
    group of persons acting with a common purpose.” Rome
    Statute of the International Criminal Court Art. 25(3)(d), July
    17, 1998, 2187 U.N.T.S. 90. The contribution must be
    “intentional,” and must be “made with the aim of furthering
    the criminal activity or criminal purpose of the group” or “in
    the knowledge of the intention of the group to commit the
    35
    crime.” 
    Id. Given its
    settled roots in international law, there
    is no dispute that Congress could authorize a military
    commission prosecution for joint criminal enterprise. See
    Oral Arg. Tr. 10.
    Classically, joint criminal enterprise differs from ordinary
    inchoate conspiracy by its requirement of action in
    furtherance of the agreement. See Allison Marston Danner &
    Jenny S. Martinez, Guilty Associations: Joint Criminal
    Enterprise, Command Responsibility, and the Development of
    International Criminal Law, 93 CAL. L. REV. 75, 119 (2005).
    The offense is also doctrinally distinct from traditional
    conspiracy because it is a form of liability, while inchoate
    conspiracy is a freestanding substantive crime. 
    Id. at 119;
    see
    also 
    Hamdan, 548 U.S. at 610
    n.40 (plurality opinion)
    (“[J]oint criminal enterprise” is a “species of liability for the
    substantive offense (akin to aiding and abetting), not a crime
    on its own.”).
    But as applied to this case, the distinctions between a
    conspiracy conviction under the 2006 Act and what a
    conviction for joint criminal enterprise would have entailed
    are narrower than they would be for traditional inchoate
    conspiracy. Bahlul’s conspiracy charge under the 2006 Act
    did require explicit proof of an overt act and involved a
    completed object offense. As a result, “it is not clear whether
    th[e] formal distinction between [joint criminal enterprise]
    and conspiracy carries much practical weight.” Danner &
    
    Martinez, supra, at 119
    ; see Peter Margulies, Defining,
    Punishing and Membership in the Community of Nations, 36
    FORDHAM INT’L L.J. 1, 86 (2013) (The “pairing of joint
    intention with action [in the Rome Statute’s codification of
    Joint Criminal Enterprise] is very close to conspiracy—close
    enough that no individual charged with the latter as a mode of
    liability can claim lack of notice.”). Whatever the distinctions
    36
    between the two, they do not make a clear or plain
    constitutional difference.
    Beyond that, Bahlul conceded at oral argument, Oral Arg.
    Tr. 9–10, that the Constitution would permit his trial before a
    military commission on a Pinkerton conspiracy theory of
    liability, see Pinkerton v. United States, 
    328 U.S. 640
    (1946).
    The Pinkerton doctrine of conspiracy holds an individual
    vicariously liable for reasonably foreseeable substantive
    crimes committed by his co-conspirators in furtherance of the
    conspiracy. See 
    id. at 646–647.
    Pinkerton “intertwines conspiracy as a substantive crime
    with conspiracy as a theory of liability[.]” Danner &
    
    Martinez, supra, at 116
    ; see, e.g., United States v. Edmond,
    
    924 F.2d 261
    , 268 (D.C. Cir. 1991) (Pinkerton established
    that commission of a substantive offense and conspiracy to
    commit it are distinct crimes, and simultaneously authorized
    holding a conspirator responsible for substantive criminal acts
    committed by a co-conspirator). But Pinkerton liability is
    distinct from inchoate conspiracy because it relies on the
    imputation of co-conspirators’ completed offenses, and
    requires a finding that they were “reasonably foresee[able] as
    a necessary or natural consequence of the unlawful
    agreement.” 
    Pinkerton, 328 U.S. at 648
    ; see also Danner &
    
    Martinez, supra, at 115
    –116. In Bahlul’s case, because he
    joined agreements to intentionally commit war crimes, acted
    in furtherance of those agreements, and was intricately
    involved in preparing two 9/11 perpetrators for their attacks, it
    is far from plain that the acts of terrorism that flowed directly
    from his conspiratorial activities were not precisely what he
    intended to have happen, let alone “reasonably foresee[able]
    as a necessary or natural consequence of the unlawful
    agreement.” 
    Pinkerton, 328 U.S. at 648
    . At least the gap
    37
    between the two forms of conspiracy is not so clear as to tie
    Congress’s legislative hands on plain-error review.
    Bahlul’s position—essentially adopted by the dissenters,
    see Joint Dissent at 52–60—is that, although a hypothetical
    conviction for common plan to wage aggressive war, joint
    criminal enterprise, or Pinkerton conspiracy would have been
    valid, his conviction here was unconstitutional because the
    2006 Act outlaws a stand-alone “conspiracy.” Oral Arg. Tr.
    9–10. But there is no dispute that the law of nations permits
    some freestanding conspiracy convictions—for aggressive
    war and genocide. So the fact that the 2006 Act denominates
    a stand-alone conspiracy offense cannot make all the
    difference.
    If Bahlul means by this argument that the 2006 Act might
    allow someone else to be convicted of ordinary, common-
    law-like conspiracy, that is not his argument to make.
    Outside the First Amendment context (which is not plausibly
    implicated here), a criminal defendant whose culpable
    conduct falls within the constitutional range cannot upend that
    conviction just because the statute’s alleged overbreadth
    might permit the unconstitutional conviction of another
    individual. See United States v. Williams, 
    553 U.S. 285
    , 304
    (2008) (“[O]rdinarily ‘a plaintiff who engages in some
    conduct that is clearly proscribed cannot complain of the
    vagueness of the law as applied to the conduct of others.’”)
    (quoting Hoffman Estates v. Flipside, Hoffman Estates, Inc.,
    
    455 U.S. 489
    , 495 (1982)) (alteration omitted).
    What matters here is that Bahlul’s own conviction was
    not for ordinary inchoate conspiracy. It was for a carefully
    crafted form of statutory conspiracy that, on the record of this
    case, resembles in important ways those forms of conspiracy
    or collective action that get the international-law nod of
    38
    approval. Surely plain-error review cannot turn on the same
    nuances of varying conspiracy-liability theories that confound
    most first-year law students. See 
    Terrell, 696 F.3d at 1260
    (requiring on-point precedent in the Supreme Court or this
    circuit to establish clear error).
    Contrary to the worry expressed in the dissenting opinion
    (at 55–60), that conclusion does not find Bahlul guilty of a
    crime for which he was not charged or convicted. Instead, I
    decide only that, given the elements of the statutory crime of
    which Bahlul was convicted and its comparability in some
    key respects to conspiracies that the parties agree transgress
    international law, Bahlul’s conviction of conspiracy under the
    2006 Act did not plainly exceed Congress’s constitutional
    authority.
    Fourth, Supreme Court precedent has not required
    slavish adherence to the precise contours of explicitly
    recognized international law as a precondition to Congress’s
    exercise of its power under the Define and Punish Clause.
    For instance, in United States v. Arjona, 
    120 U.S. 479
    (1887),
    the Court held that the Define and Punish Clause gave
    Congress the authority to punish an individual who
    counterfeited another nation’s securities, 
    id. at 487–488.
    The
    Court did not identify any express international proscription
    on counterfeiting securities, but explained that the prohibition
    on counterfeiting money might, “with just propriety, be
    extended to the protection of this more recent custom among
    bankers of dealing in foreign securities[.]” 
    Id. at 486.
    For
    that reason, the Supreme Court concluded, “a law which is
    necessary and proper to afford this protection” fell within
    Congress’s Article I power because the law was “needed to
    carry into execution a power conferred by the constitution on
    the government of the United States exclusively.” 
    Id. 39 Arjona
    thus held that Congress’s power to criminalize an
    offense did not turn on whether the act was expressly
    prohibited by international law. Instead, it was sufficient that
    proscribing certain conduct was “necessary and proper” to
    protect rights implicitly recognized by the law of nations.
    Likewise, in In re Yamashita, 
    327 U.S. 1
    (1946), the
    Supreme Court affirmed the conviction of a Japanese military
    commander before a military commission for “permitting [his
    troops] to commit brutal atrocities and other high crimes
    against people of the United States and of its allies and
    dependencies,” 
    id. at 13–14.
    Even though international law
    had not expressly recognized liability for such supervisorial
    conduct, the Court noted that international law outlined the
    commander’s duty to uphold the law of war. See 
    id. at 15–16
    (Geneva Conventions imposed on the commander an
    affirmative “duty * * * to provide for the details of execution
    of the foregoing articles (of the convention)”); cf. 
    id. at 40
    (Murphy, J., dissenting) (protesting that Yamashita’s
    conviction was not “based upon charges fairly drawn in light
    of established rules of international law and recognized
    concepts of justice”). What proved critical in Yamashita was
    that the commander’s offense—the failure to restrain
    subordinate troops—“would almost certainly result in
    violations which it is the purpose of the law of war to
    prevent.” 
    Id. at 15
    (majority opinion).
    So too here. Bahlul’s statutory conspiracy conviction and
    the commission’s factual determinations on which it rested
    are closely tied to offenses against the “Law of Nations”
    within the meaning of the Constitution’s Define and Punish
    Clause, Art. I, § 8, cl. 10. At a bare minimum, plain-error
    review does not leave Congress powerless to do nothing more
    than mimic the precise contours of extant international
    precedent.
    40
    Fifth and finally, plain-error review requires Bahlul to
    identify “clear precedent” from this court or the Supreme
    Court “establish[ing] [the] erroneous character” of his
    conspiracy conviction, 
    Terrell, 696 F.3d at 1260
    . But the
    closest precedent from this court is our prior en banc decision
    in Bahlul I, which points in the opposite direction. There, a
    majority of this court held that it is not “plain” that conspiracy
    falls outside the statutory limits on crimes triable by military
    
    commission. 767 F.3d at 22
    . Because the Ex Post Facto
    Clause, U.S. CONST., Art. I, § 9, cl. 3, forbade reliance on the
    2006 Act, the court had to determine whether Bahlul’s
    inchoate conspiracy conviction fell plainly outside the “law of
    war” within the meaning of the Articles of War, 10 U.S.C.
    § 821. See Bahlul 
    I, 767 F.3d at 22
    . Under the Articles of
    War, conspiracy had to be an offense that “by the law of war
    may be tried by military commissions.” 10 U.S.C. § 821.
    As this court explained in Bahlul I, the Supreme Court
    has not yet resolved the question whether “law of war” means
    only the international law of war or includes “the common
    law of war developed in U.S. military 
    tribunals.” 767 F.3d at 22
    –23. But on plain-error review, it was sufficient that the
    Supreme Court has relied on domestic precedent in addition
    to international law to ascertain whether a crime is triable as
    an offense against the “law of war.” 
    Id. at 23–24
    (citing
    
    Hamdan, 548 U.S. at 603
    –609 (plurality opinion); 
    id. at 689–
    704 (Thomas, J., dissenting); 
    Quirin, 317 U.S. at 31
    –35, 42
    n.14; 
    Yamashita, 327 U.S. at 19
    –20).
    So too here, three examples of domestic wartime
    precedent make it far from plain that conspiracy under the
    2006 Act would not be triable by military commission.
    For starters, the individuals held responsible for President
    Lincoln’s assassination were charged with and convicted of
    41
    “combining, confederating, and conspiring together * * * to
    kill and murder, within the Military Department of
    Washington, and within the fortified and intrenched lines
    thereof, Abraham Lincoln[.]” H.R. Doc. No. 314, 55th Cong.,
    3d Sess., 696 (1899). President Andrew Johnson personally
    approved the convictions, relying in part on the opinion of
    Attorney General James Speed advising that the individuals
    could be tried for conspiracy before a military commission.
    11 Op. Att’y Gen. at 297. As this court explained in Bahlul I,
    “this highest-level Executive Branch deliberation is worthy of
    respect in construing the law of 
    war.” 767 F.3d at 25
    (citing
    Sosa v. Alvarez-Machain, 
    542 U.S. 692
    , 733–734 (2004)).
    In addition, Nazi saboteurs who entered the United States
    intending to destroy industrial facilities were convicted of
    conspiracy in Quirin and in Colepaugh v. Looney, 
    235 F.2d 429
    , 431–432 (10th Cir. 1956). While the Supreme Court and
    the Tenth Circuit each affirmed the saboteurs’ convictions
    based on other charges, those decisions are “prominent
    example[s]” of conspiracy charges reached in law-of-war
    military commissions, approved by the executive, and
    permitted by the judiciary, including the Supreme Court.
    Bahlul 
    I, 767 F.3d at 26
    .
    Lastly, during the Korean War, General Douglas
    MacArthur ordered that persons accused of “conspiracies and
    agreements to commit * * * violations of the laws and
    customs of war of general application” be tried by military
    commission.    Letter Order, Gen. HQ, United Nations
    Command, Tokyo, Japan, Trial of Accused War Criminals
    (Oct. 28, 1950) (Rules of Criminal Procedure for Military
    Commissions, Rule 4).
    While not definitively answering the ultimate
    constitutional question, “the historical practice of our wartime
    42
    tribunals is sufficient to make it not ‘obvious’ that conspiracy
    was not traditionally triable by [a] law-of-war military
    commission” under the Articles of War as an offense against
    the law of war. Bahlul 
    I, 767 F.3d at 27
    (citing 
    Olano, 507 U.S. at 734
    ). Further, because the “law of war” in the Articles
    of War “incorporate[s] by reference, as within the jurisdiction
    of military commissions, all offenses which may
    constitutionally be included within that jurisdiction,” 
    Quirin, 317 U.S. at 30
    , those same domestic precedents underscore
    the absence of any plain constitutional error in Bahlul’s
    statutory conspiracy conviction by a military commission.
    IV
    Bahlul’s other constitutional challenges also cannot
    surmount plain-error review.
    First, he argues that his conspiracy conviction runs afoul
    of the Constitution’s Judicial Power Clause, Art. III, § 2, cl. 1.
    But precedent has long established that criminal prosecutions
    for violations of the law of war do not fall within the
    exclusive jurisdiction of Article III courts. See, e.g., Johnson
    v. Eisentrager, 
    339 U.S. 763
    , 786 (1950) (lawfulness of
    military commission jurisdiction is “well-established”);
    Bahlul 
    II, 792 F.3d at 7
    (citing 
    Quirin, 317 U.S. at 46
    ).
    Bahlul’s argument that his statutory conspiracy conviction
    falls beyond the law of nations amounts to nothing more than
    a repackaging of his Define and Punish Clause argument.
    The error—if any—is just as far from plain under Article III
    as it is under Article I.
    Second, Bahlul contends that his conviction violated his
    right to a trial by jury. Bahlul is correct that Article III,
    Section 2, Clause 3 of the Constitution provides that “[t]he
    Trial of all Crimes, except in Cases of Impeachment, shall be
    43
    by Jury.”   But if any error occurred, it was not plain or
    obvious.
    To begin with, no established precedent even extends the
    jury trial right to non-citizens being held outside the United
    States’ sovereign territory. In Boumediene v. Bush, 
    553 U.S. 723
    (2008), the Supreme Court for the first time extended
    constitutional protection to an alien at Guantanamo Bay, 
    id. at 7
    95. That holding, however, was “explicitly confined * * *
    ‘only’ to the extraterritorial reach of the Suspension Clause,”
    and expressly “disclaimed any intention to disturb existing
    law governing the extraterritorial reach of any constitutional
    provisions, other than the Suspension Clause.” Rasul v.
    Myers, 
    563 F.3d 527
    , 529 (D.C. Cir. 2009) (quoting
    
    Boumediene, 553 U.S. at 795
    ). And it is settled that certain
    other constitutional provisions do not protect aliens outside
    the sovereign United States. See, e.g., United States v.
    Verdugo-Urquidez, 
    494 U.S. 259
    , 261 (1990) (the Fourth
    Amendment does not apply to the search and seizure of
    property owned by a nonresident alien and located abroad);
    Kiyemba v. Obama, 
    555 F.3d 1022
    , 1026 & n.9 (D.C. Cir.
    2009) (Due Process Clause of Fifth Amendment does not
    apply to aliens at Guantanamo), vacated, 
    559 U.S. 131
    (2010)
    (per curiam), reinstated on remand, 
    605 F.3d 1046
    (D.C. Cir.
    2010) (per curiam), cert. denied, 
    563 U.S. 954
    (2011).
    If anything, precedent undermines Bahlul’s claim. In
    Quirin, the Supreme Court held that Nazi saboteurs had no
    right to trial by jury, explaining that “trial by a jury of the
    vicinage where the crime was committed” was a “procedure[]
    unknown to military tribunals, which are not courts in the
    sense of the Judiciary 
    Article.” 317 U.S. at 39
    . Article III’s
    Jury Trial Clause, the Supreme Court elaborated, “preserve[d]
    unimpaired trial by jury in all those cases in which it had been
    recognized by the common law.” 
    Id. But it
    did not go so far
    44
    as “to have extended the right to demand a jury to trials by
    military commission, or to have required that offenses against
    the law of war not triable by jury at common law be tried only
    in the civil courts.” 
    Id. at 40.
    Bahlul contends that, under Quirin, the jury-trial right
    hinges on whether a charge was triable by jury at common
    law, not whether the charge was also properly tried before the
    military commission. Pet. Br. 27; Oral Arg. Tr. 15–16. The
    sabotage charge in Quirin did not entail a jury trial right at
    common law, but conspiracy did. See Callan v. Wilson, 
    127 U.S. 540
    , 549 (1888).
    Subsequent precedent indicates otherwise. See Whelchel
    v. McDonald, 
    340 U.S. 122
    , 127 (1950) (“The right to trial by
    jury guaranteed by the Sixth Amendment is not applicable to
    trials by courts-martial or military commission.”); Sanford v.
    United States, 
    586 F.3d 28
    , 35 (D.C. Cir. 2009) (“[T]he Sixth
    Amendment right to a criminal jury trial does not, itself, apply
    to the military.”); cf. Granfinanciera S.A. v. Nordberg, 
    492 U.S. 33
    , 53 (1989) (“[I]f Congress may assign the
    adjudication of a statutory cause of action to a non-Article III
    tribunal, then the Seventh Amendment poses no independent
    bar to the adjudication of that action by a nonjury
    factfinder.”). There accordingly is nothing plain or obvious
    about Bahlul’s entitlement to a trial by jury.
    Third, Bahlul argues that the First Amendment’s free
    speech guarantee forecloses a conviction for his political
    speech, namely the al Qaeda recruitment video he created
    about the terrorist attack on the USS Cole. Pet. Br. 38, 40,
    Bahlul II, 
    2014 WL 3962849
    . As with Bahlul’s claimed jury-
    trial right, no governing precedent extends First Amendment
    protection to speech undertaken by non-citizens on foreign
    soil, so no plain error occurred.
    45
    What is settled, moreover, is that the First Amendment
    offers no shield to speech like Bahlul’s that is “directed to
    inciting or producing imminent lawless action and * * * [is]
    likely to incite or produce such action.”          Holder v.
    Humanitarian Law Project, 
    561 U.S. 1
    , 43–44 (2010)
    (alterations omitted; quoting Brandenburg v. Ohio, 
    395 U.S. 444
    , 447 (1969) (per curiam)); see also 
    Bahlul, 820 F. Supp. 2d at 1249
    (Bahlul’s USS Cole recruitment video
    was “aimed at inciting viewers to join al Qaeda, to kill
    Americans, and to cause destruction.”).
    Fourth, Bahlul argues that the 2006 Act violates the Fifth
    Amendment’s guarantee of equal protection because it
    authorized trials before a military commission for alien enemy
    combatants, but not for enemy combatants who are U.S.
    citizens. The short answer is that no relevant precedent
    plainly or clearly supports the application of equal protection
    principles in this law-of-war context to foreign enemy
    combatants.
    V
    In sum, I would review Bahlul’s constitutional challenges
    only for plain error. Under that standard, I would hold that
    his conviction for conspiracy under the 2006 Act by a law-of-
    war military commission did not plainly exceed Congress’s
    power under Article I’s Define and Punish Clause or trench
    upon Article III’s assignment of the judicial power to federal
    courts. Nor did his conviction violate any of the other
    constitutional protections Bahlul invokes. I accordingly
    concur in the judgment affirming Bahlul’s conviction.
    WILKINS, Circuit Judge, concurring: I agree with much of
    the reasoning in section III of Judge Millett’s opinion, but my
    view of this case differs in two ways. First, I do not believe a
    plain error standard applies. For the reasons set forth in the
    2015 panel opinion, Bahlul cannot forfeit his structural
    Article III claim. See Al Bahlul v. United States, 
    792 F.3d 1
    ,
    3-7 (D.C. Cir. 2015), vacated by order granting rehearing en
    banc, Al Bahlul v. United States, No. 11-1324 (D.C. Cir. Sept.
    25, 2015); see also Commodity Futures Trading Comm’n v.
    Schor, 
    478 U.S. 833
    , 850-51 (1986). “Every extension of
    military jurisdiction is an encroachment on the jurisdiction of
    the civil courts,” 
    Bahlul, 792 F.3d at 5
    (quoting Reid v.
    Covert, 
    354 U.S. 1
    , 21 (1957) (plurality)), meaning Bahlul’s
    challenge “goes to the heart of the judiciary’s status as a
    coordinate branch of government,” 
    id. at 6.
    Whether his
    conspiracy conviction falls within the Article III exception for
    law-of-war military commissions should be a question for de
    novo review.
    The second reason I write separately is because there is
    no constitutional violation under a de novo standard.
    “Embedded in the traditional rules governing constitutional
    adjudication is the principle that a person to whom a statute
    may constitutionally be applied will not be heard to challenge
    that statute on the ground that it may conceivably be applied
    unconstitutionally to others, in other situations not before the
    Court.” Broadrick v. Oklahoma, 
    413 U.S. 601
    , 610 (1973);
    see also New York v. Ferber, 
    458 U.S. 747
    , 767 (1982).
    Accordingly, to review Bahlul’s claim, we must test the
    premise of his contention as applied to him. His particular
    conviction is far from one for ordinary, inchoate conspiracy.
    An examination of the record shows Bahlul was really
    convicted of an offense tantamount to substantive war crimes
    under a Pinkterton theory of liability. It is not that “any delta
    between his conspiracy offense and those offenses that
    international law proscribes is too narrow to rise to the level
    of plain constitutional error.” Millett Op. 32. There is no
    2
    delta. The government proved beyond a reasonable doubt that
    Bahlul knowingly took part in al-Qaeda’s plan on September
    11, 2001 to murder American civilians. His statutory
    conspiracy conviction does not violate international law,
    which recognizes what is essentially Pinkerton liability, and it
    therefore comports with Article III. See 
    Bahlul, 792 F.3d at 22
    (“The international law of war limits Congress's authority
    because the Constitution expressly ties that authority to ‘the
    Law of Nations.’”) (quoting U.S. CONST. art. I, § 8, cl. 10).
    I.
    Bahlul attacks his conviction for conspiracy under
    Section 950v(b)(28) of the 2006 Military Commission Act
    (“2006 MCA”), Pub. L. No. 109-366, 120 Stat. 2600. He
    alleges that the MCA conspiracy crime violates Article III
    because the prosecution of inchoate conspiracy violates
    international law. In other words, Bahlul mounts a facial
    challenge to the statute, and in so doing assumes that his
    conviction in fact implicates inchoate conspiracy. But we
    cannot take Bahlul at his word. Instead, we must scrutinize
    the statute, and then examine the specific facts of his
    conviction to see whether it actually bears on the
    constitutional principle asserted. See United States v. Stevens,
    
    559 U.S. 460
    , 474 (2010); Vill. of Hoffman Estates v.
    Flipside, Hoffman Estates, Inc., 
    455 U.S. 489
    , 494-95 (1982).
    In line with decades of express Supreme Court instruction in
    this regard, we must treat this case as an as-applied challenge.
    And when we ask ourselves whether Bahlul was really
    prosecuted for inchoate conspiracy, the answer is clearly no.
    This framework of examining Bahlul’s constitutional
    challenge to his MCA conviction “[b]y focusing on the
    factual situation before us” is long-accepted practice. 
    Ferber, 458 U.S. at 768
    ; see also Sabri v. United States, 
    541 U.S. 600
    ,
    3
    609 (2004); Chapman v. United States, 
    500 U.S. 453
    , 467
    (1991); Bd. of Trustees of State Univ. of N.Y. v. Fox, 
    492 U.S. 469
    , 484-85 (1989); N.Y. State Club Ass’n, Inc. v. City of
    N.Y., 
    487 U.S. 1
    , 11 (1988); Vill. of Hoffman 
    Estates, 455 U.S. at 495
    n.7; United States v. Mazurie, 
    419 U.S. 544
    , 550
    (1975); 
    Broadrick, 413 U.S. at 610
    ; United States v. Powell,
    
    423 U.S. 87
    , 92 (1975).
    It is by now a maxim that a facial attack on a criminal
    statute simply cannot prevail where the law is constitutional
    as applied to a defendant’s own conduct. See Schall v.
    Martin, 
    467 U.S. 253
    , 268 n.18 (1984) (“[O]utside the limited
    First Amendment context, a criminal statute may not be
    attacked as overbroad.”) (citing Ferber, 
    458 U.S. 747
    ); see
    also Holder v. Humanitarian Law Project, 
    561 U.S. 1
    , 20
    (2010) (“[A] plaintiff who engages in some conduct that is
    clearly proscribed cannot complain of the vagueness of the
    law as applied to the conduct of others.”) (citing Vill. of
    Hoffman 
    Estates, 455 U.S. at 495
    ). The Supreme Court has
    often cautioned that “[f]acial challenges of this sort are
    especially to be discouraged,” 
    Sabri, 541 U.S. at 609
    , and
    “[t]he fact that [a criminal statute] might operate
    unconstitutionally under some conceivable set of
    circumstances is insufficient to render it wholly invalid.” 1
    1
    There is some controversy in recent years about whether the
    Salerno standard universally applies. See Hodge v. Talkin, 
    799 F.3d 1145
    , 1156 (D.C. Cir. 2015) (“[T]he Court has also indicated
    that the standard for facial invalidity may be less stringent in some
    situations, instead turning on whether the statute lacks any ‘plainly
    legitimate sweep.’” (quoting Wash. State Grange v. Wash. State
    Republican Party, 
    552 U.S. 442
    , 449 (2008))). At the very least,
    “all agree that a facial challenge must fail where the statute has a
    plainly legitimate sweep,” 
    id. at 450
    (internal quotations marks
    omitted), a standard Bahlul’s conviction necessarily survives given
    that the facts of his own case do not violate Article III. See also 
    id. 4 United
    States v. Salerno, 
    481 U.S. 739
    , 745 (1987). “Indeed,
    this is why facial constitutional challenges [have been] . . .
    unsuccessful as defenses to criminal prosecutions for non-
    expressive conduct.” 2 Coleman v. DeWitt, 
    282 F.3d 908
    , 914
    n.3 (6th Cir. 2002).
    While Bahlul attempts to deflect attention from his own
    circumstances by erecting a straw man, it is not our job to
    answer the abstract question of whether prosecuting inchoate
    conspiracy violates our separation of powers – we do not even
    examine whether the elements of Section 950v(b)(28)
    generally equate to a prosecution for inchoate conspiracy.
    Rather, we examine whether the acts committed and proven in
    the course of this specific prosecution really equate with
    inchoate conspiracy. This jurisprudential approach does not
    “violate basic principles of criminal justice,” as the dissent
    urges. See Dissenting Op. at 53. We employ it not just with
    regard to criminal statutes, but throughout constitutional
    adjudication, including in the Article III context. We treat a
    facial separation of powers challenge “as if it were an as-
    applied challenge,” and reject it where the particular
    application of the statute at issue was constitutional. U.S. ex
    rel. Schweizer v. Oce N.V., 
    677 F.3d 1228
    , 1235 & n.7 (D.C.
    Cir. 2012) (citing Texas v. Johnson, 
    491 U.S. 397
    , 403 n.3
    (1989)); see also Free Enter. Fund v. Pub. Co. Accounting
    Oversight Bd., 
    537 F.3d 667
    , 670 (D.C. Cir. 2008) (“To
    succeed in its facial challenge to Title I of the Act under the
    (“[W]e must be careful not to go beyond the statute’s facial
    requirements and speculate about ‘hypothetical’ or ‘imaginary’
    cases.”).
    2
    As Judge Millett’s opinion points out, the First Amendment
    context is not implicated here by Bahlul’s Article III challenge. See
    Millett Op. 37.
    5
    Appointments Clause and separation of powers, the Fund
    bears a heavy burden to show that the provisions of which it
    complains are unduly severe in all circumstances and cannot
    be constitutionally applied.”) (footnote omitted), aff’d in part,
    rev’d in part and remanded, 
    561 U.S. 477
    (2010).
    Evaluated in this way, Bahlul’s facial challenge must fail
    because his own conviction does not violate Article III. See
    infra Part III. He was not convicted of inchoate conspiracy.
    It does not matter that Bahlul framed his argument as a facial
    attack; an appellant cannot change our approach to deciding
    constitutional issues “by concession, inadvertence, poor oral
    advocacy or otherwise.” 3 Millett Op. 22 (quoting 
    Bahlul, 792 F.3d at 32
    n.3 (Henderson, J., dissenting)). Waiver and
    forfeiture rules have no application in this regard. Nor are
    there any “serious due process concerns” raised by this
    approach to Bahlul’s collateral attack, brought at the eleventh
    hour following a trial during which he presented no defense,
    and after he admitted to all but one of the factual allegations
    against him. Dissenting Op. at 61. It would be particularly
    ill-advised to ignore the “usual judicial practice” of deciding
    the as-applied question before proceeding to a facial
    challenge, 
    Fox, 492 U.S. at 484
    , given that “[s]triking down
    an Act of Congress ‘is the gravest and most delicate duty that
    this Court is called on to perform.’” Shelby Cty. v. Holder,
    
    133 S. Ct. 2612
    , 2631 (2013) (quoting Blodgett v. Holden,
    
    275 U.S. 142
    , 148 (1927) (Holmes, J., concurring)). This
    “delicate power of pronouncing an Act of Congress
    unconstitutional is not to be exercised with reference to
    3
    For this same reason, the Court did not consider itself restricted to
    Citizens United’s exact framing of its challenge on appeal. Citizens
    United v. Fed. Election Comm’n, 
    558 U.S. 310
    , 331 (2010) (“The
    parties cannot enter into a stipulation that prevents the Court from
    considering certain remedies if those remedies are necessary to
    resolve a claim that has been preserved.”).
    6
    hypothetical cases thus imagined.” United States v. Raines,
    
    362 U.S. 17
    , 22 (1960). But that is what we would be doing if
    we allowed ourselves to be hurled headlong into the structural
    Article III claim served up by Bahlul, despite the fact that the
    record of his conviction raises no such constitutional concern.
    While the separation of powers question potentially
    implicated by this case is a critical one, it is not actually
    implicated by the facts before us. If it were, I would be
    inclined to agree with the dissent. However, I cannot join that
    opinion today on account of the specifics of Bahlul’s
    conviction, which, for the following reasons, shows he was
    not convicted of inchoate conspiracy.
    II.
    There are several features of inchoate conspiracy that
    make it the “darling of the modern prosecutor’s nursery.”
    Harrison v. United States, 
    7 F.2d 259
    , 263 (2d Cir. 1925). At
    its “essence,” conspiracy is “an agreement to commit an
    unlawful act.” Iannelli v. United States, 
    420 U.S. 770
    , 777
    (1975). The agreement is the prohibited actus reus. 2
    WAYNE R. LAFAVE, SUBSTANTIVE CRIMINAL LAW § 12.2(a)
    (2d ed. 2003). It is not necessary that the parties to the
    conspiracy actually succeed in committing the crime. See
    United States v. Jimenez Recio, 
    537 U.S. 270
    , 274 (2003).
    Many jurisdictions require an overt act in furtherance of the
    conspiracy, but the overt act itself does not have to be
    unlawful. LAFAVE § 12.2(b). The government often proves
    the existence of the agreement through circumstantial
    evidence, 
    id. § 12.2(a),
    and does not need to show express
    agreement to the plan’s every detail, see Blumenthal v.
    United States, 
    332 U.S. 539
    , 557 (1947). Impossibility is not
    a defense, the merger rule does not apply, and withdrawal
    from the conspiracy is difficult, requiring an affirmative step.
    7
    See Neal Katyal, Conspiracy Theory, 112 YALE L.J. 1307,
    1309 (2003).
    Conspiracy’s detractors therefore disapprove of it as a
    vague, “elastic, sprawling and pervasive offense.” Krulewitch
    v. United States, 
    336 U.S. 440
    , 445 (1949) (Jackson, J.,
    concurring). At the same time, outlawing conspiracy is
    important to prevent crimes before they are actually
    committed. See LAFAVE § 12.1(c); see also 
    Katyal, supra, at 1313
    (“[W]ith giving prosecutors more tools for leverage over
    conspirators comes the possibility of . . . preventing some
    crime before it happens.”). We punish inchoate crimes
    precisely because they constitute “[a] step toward the
    commission of another crime, the step in itself being serious
    enough to merit punishment.” Inchoate Offense, BLACK'S
    LAW DICTIONARY (10th ed. 2014). Put another way, waiting
    for the crime to be completed needlessly puts people at risk.
    See Br. of Amici Curiae Former Gov’t Officials et al. 15
    [hereinafter Former Gov’t Officials].          Conspiracy is
    particularly advantageous in this regard because the crime is
    complete at the moment of agreement; unlike an attempt
    crime, it can be punished even before a substantial step
    towards the offense is taken. See LAFAVE § 12.1(c).
    Importantly, conspiracy is at once a stand-alone crime,
    and also a theory of liability. As a stand-alone crime against
    the United States, for example, conspiracy requires several
    things. See 18 U.S.C. § 371. There must be an agreement by
    two or more persons to commit an offense. The defendant
    must deliberately join the conspiracy with knowledge of this
    purpose. And, one of the conspiracy members must, at some
    time during its existence, perform an overt act to further or
    advance the purpose of the agreement. See id.; United States
    v. Treadwell, 
    760 F.2d 327
    , 333 (D.C. Cir. 1985); see also 2
    8
    KEVIN F. O’MALLEY ET AL., FEDERAL JURY PRACTICE &
    INSTRUCTIONS § 31:03 (6th ed. 2008) [hereinafter FED. JURY].
    Alternatively, as a form of vicarious liability – so-called
    Pinkerton liability – a member to a conspiracy can be held
    liable for reasonably foreseeable offenses committed by
    others in the group. See Pinkerton v. United States, 
    328 U.S. 640
    , 646-47 (1946) (“And so long as the partnership in crime
    continues, the partners act for each other in carrying it
    forward”).     Under a Pinkerton theory, a defendant’s
    responsibility for the underlying offense generally requires
    that the substantive offense be reasonably foreseeable and
    committed in furtherance of the conspiracy’s objectives, all
    while the defendant was a member of the conspiracy. See
    United States v. Washington, 
    106 F.3d 983
    , 1011 (D.C. Cir.
    1997); FED. JURY § 31:10.
    Bahlul argues that conspiracy is “dangerously broad in its
    sweep when used to punish the enemy in war.” Pet’r Br. 24.
    He and Amici essentially warn that all the so-called evils of
    inchoate conspiracy – that it is easy to charge, overbroad, and
    difficult to defend – are amplified when the offense is tried by
    a law-of-war military commission, as opposed to an Article
    III court. See Pet’r Br. 29, 33-34; Br. of Amici Curiae Int’l
    Law Scholars 16-19. That may be true, but for the reasons
    that follow, Bahlul’s conviction shares little in common with
    the above-described features of inchoate conspiracy, and
    instead bears a close kinship to a conviction under a Pinkerton
    theory, which does not offend the Constitution.
    III.
    The 2006 MCA contained important limitations on
    military commission authority that distinguish this
    prosecution from that of ordinary, vanilla conspiracy. As
    9
    Judge Millett’s opinion points out, there is a real question as
    to whether the conspiracy offense codified by the MCA
    amounts to inchoate conspiracy. See Millett Op. 29-30.
    Significantly, the statute specifically references victims,
    containing two sentencing variations depending on whether
    anybody dies as a result of the conspiracy. 10 U.S.C.
    § 950v(b)(28) (2006). In other words, by conditioning
    punishment on either death or other harm befalling another
    person, the MCA’s version of conspiracy contemplates the
    completion of a substantive offense. That is a far cry from
    inchoate conspiracy, which is achieved “even though the
    substantive offence is not successfully consummated.”
    Inchoate, BLACK’S LAW DICTIONARY (10th ed. 2014)
    (quoting Andrew Ashworth, PRINCIPLES OF CRIMINAL LAW
    395 (1991)). Bahlul does not ask us to decide if the MCA’s
    version of conspiracy always requires a completed offense,
    but in this case there is one: the September 11th attacks.
    Consider next that in a typical prosecution for inchoate
    conspiracy, the government need only prove that someone
    who was a member of the conspiracy committed the requisite
    overt act. 
    Pinkerton, 328 U.S. at 646-47
    (“It is settled that ‘an
    overt act of one partner may be the act of all without any new
    agreement specifically directed to that act.’”) (quoting United
    States v. Kissel, 
    218 U.S. 601
    , 608 (1910)); FED. JURY
    § 31:07. Accordingly, ordinary conspiracy jury instructions
    say that the acts of co-conspirators can be considered proof of
    the conspiracy charge against the defendant. FED. JURY
    § 31:06. No similar instruction was given in Bahlul’s trial.
    By contrast, the MCA’s version of conspiracy requires, and
    the commission was instructed that it must find, that Bahlul
    committed an overt act himself. See 10 U.S.C. § 950v(b)(28);
    Trial Tr. 846 (directing that the panel find Bahlul “knowingly
    committed at least one of the following overt acts for the
    10
    purpose of bringing about one of the objects of the
    agreement.”).
    Not only does the MCA’s statutory conspiracy require a
    victim and a defendant’s own overt act, but what was proven
    at Bahlul’s trial also goes far beyond conspiracy’s traditional
    requirements. The commission’s special verdict form and ten
    factual findings show that Bahlul was on trial for something
    that he himself did as part of al-Qaeda’s criminal plan to kill
    nearly 3,000 civilians by flying planes into the World Trade
    Center. See App. 116-17. And according to the evidence and
    the commission’s findings, he did a lot. He played a
    particularly valuable role supporting two of the 9/11
    hijackers, Mohammed Atta and Ziad al Jarrah. Although at
    the time he was not aware of the specifics of the September
    11th plan, the prosecution introduced evidence that Bahlul
    roomed with Atta and al Jarrah in Afghanistan, the
    roommate’s role typically being to motivate and focus the
    operatives, as well as to keep an eye on them in case they
    decide to change their minds. Trial Tr. 555-56. More than
    that, in a 2005 letter, Bahlul admitted that he arranged for
    Atta and al Jarrah to pledge their loyalty oaths to bin Laden,
    and “also typed their martyr wills on a computer and
    personally handed it to Sheikh Usamah Bin-Landin [sic].”
    App. 145 (Prosecution Ex. 15). Martyr wills are a crucial
    aspect of al-Qaeda’s twisted ideology and operations. They
    are declarations that a suicide operative reads into a camera,
    describing in general terms the terrorist act he is yet to carry
    out. Trial Tr. 554. The point of the videotaped message is to
    motivate the operative, incite others to follow his example,
    spread fear among al-Qaeda’s enemies, and allow the
    organization to later prove its responsibility for the terrorist
    act. 
    Id. at 554,
    798-99, 808. “I praise Almighty Allah,” wrote
    Bahlul, “for allowing me to have [this] simple and indirect
    role” in the 9/11 events. App. 145 (Prosecution Ex. 15).
    11
    All of this amounts to Bahlul’s Pinkerton liability for at
    least the murder of protected persons. See 10 U.S.C.
    §§ 950v(a)(2), (b)(1) (outlawing “murder of protected
    persons,” defined as “any person entitled to protection under
    one or more of the Geneva Conventions”); see also Millett
    Op. 31 (describing the MCA object offenses that violate
    Article 3 of the Geneva Conventions). The record shows
    that, during his membership in the conspiracy, Bahlul helped
    further the conspiracy’s goal of committing substantive war
    crimes. Even though the commission was instructed that
    “[p]roof that [a substantive offense] of [murder of protected
    persons, etc.] . . . actually occurred is not required,” Trial Tr.
    848, it nonetheless twice confirmed just that; the commission
    returned specific findings that Atta and al Jarrah committed
    the September 11, 2001 attacks, App. 117, and that “at the
    direction of Usama bin Laden, [Bahlul] researched the
    economic effect of September 11, 2001, attacks on the United
    States and provided the result of his research to Usama bin
    Laden,” App. 117. The entire aim of the conspiracy was to
    murder civilians. See App. 115; Trial Tr. 849 (explaining it
    necessary to prove beyond a reasonable doubt that “the
    agreement intended every element” of the substantive war
    crimes). And the commission found that Bahlul purposefully
    joined al-Qaeda, App. 116, was a conspiracy member during
    and after the attacks, see App. at 117, as well as prepared the
    martyr wills of Atta and al Jarrah “in preparation for the acts
    of terrorism perpetrated . . . on September 11, 
    2001,” 4 Ohio App. at 117
    (emphasis added); see also Trial Tr. 849 (instructing
    that “[t]he overt act . . . must be a clear indication that the
    4
    Bahlul’s counsel suggests he transcribed the martyr wills
    “apparently after the September 11th attacks.” Pet’r Br. 3 (citing
    Pet’r App. 141-45). In any case, the commission specifically found
    that Bahlul prepared them before September 11, 2001. App. 117.
    12
    conspiracy is being carried out.”). In sum, the government
    proved all of the Pinkerton elements beyond a reasonable
    doubt.
    At oral argument, Bahlul’s counsel conceded that a
    conviction under the Pinkerton doctrine does not violate the
    Constitution. Oral Arg. Tr. 9-10. He could not have
    answered otherwise, as joint criminal enterprise (“JCE”) is a
    recognized theory of vicarious liability within the
    international community. 5 See Hamdan v. Rumsfeld, 
    548 U.S. 557
    , 611 n.40 (2006) (plurality); Br. of Amici Curiae
    Int’l Law Scholars 10; Br. of Amici Curiae Former Gov’t
    Officials 6. There are actually three forms of JCE. See
    Prosecutor v. Tadíc, Case No. IT-94-1-A, Judgment, ¶ 220
    (Int’l Crim. Trib. for the Former Yugoslavia July 15, 1999).
    The third variant, or “extended” JCE, occurs when there is “a
    common purpose to commit a crime where one of the
    perpetrators commits an act which, while outside the common
    purpose, is nevertheless a natural and foreseeable
    consequence of the effecting of that common purpose.”
    Prosecutor v. Vasiljevic, Case No. IT-98-32-A, Judgment,
    ¶ 99 (Int’l Crim. Trib. for the Former Yugoslavia Feb. 25,
    2004); see also 
    id. at ¶¶
    94-101 (summarizing elements of
    JCE I-III); Tadíc, Case No. IT-94-1-A, Judgment, at ¶ 204.
    This is essentially the Pinkerton doctrine. 6 See Elies van
    5
    “[V]ariously called joint criminal enterprise, common purpose, or
    common plan liability,” JCE finds support “in World War II-era
    jurisprudence and in cases from the [International Criminal
    Tribunal for the Former Yugoslavia].” Brief for Specialists in
    Conspiracy and International Law as Amici Curiae Supporting
    Petitioner at 19, Hamdan v. Rumsfeld, 
    548 U.S. 557
    (2006)
    (No. 05-184) [hereinafter Hamdan Amici].
    6
    The Hamdan Amici argued that JCE “differs sharply” from
    Pinkerton liability, but offered little more than an explanation that
    13
    Sliedregt, Criminal Responsibility in International Law, 14
    EUR. J. CRIME, CRIM. L. & CRIM. JUST. 81, 97 (2006) (“The
    closest national equivalent of Third Category JCE is the so-
    called American concept of ‘Pinkerton conspiracy.’”); Jens
    David Ohlin, Joint Intentions to Commit International
    Crimes, 11 CHI. J. INT’L L. 693, 703 (2011) (“The standard
    itself for JCE III stems from the Pinkerton v United States
    doctrine . . . . Indeed, even the language in Tadíc is borrowed,
    inter alia, from Pinkerton.”).
    Because the factual elements that were proven during
    Bahlul’s prosecution were indistinguishable from a theory
    recognized under international law, it does not offend the
    Constitution.     See 
    Bahlul, 792 F.3d at 24
    (Tatel, J.,
    concurring) (“[T]he weight of the Court's language in Quirin
    strongly indicates that the law-of-war exception is exclusively
    international.”). As a result, I do not believe we should reach
    out and decide additional constitutional issues not necessary
    to resolve this appeal, which is why I am unwilling to wade
    into the waters pursued by Judge Kavanaugh. See Ex parte
    Quirin, 
    317 U.S. 1
    , 45-46 (1942) (“We have no occasion now
    to define with meticulous care the ultimate boundaries of the
    jurisdiction of military tribunals to try persons according to
    the law of war. It is enough that petitioners here, upon the
    JCE, as a theory of vicarious liability, is not the same as an inchoate
    offense. Hamdan Amici at 20. Amici in our case do not make a
    similar claim. That argument is perhaps driven by the need to
    “distance” JCE from “a formulation that sounds too much like
    conspiracy. The received wisdom among international lawyers is
    that conspiracy is a decidedly common law doctrine that finds
    insufficient international support to be considered part of
    international criminal law. Consequently, if JCE amounts to ersatz
    conspiracy, it will be rejected too.” Jens David Ohlin, Joint
    Intentions to Commit International Crimes, 11 CHI. J. INT’L L. 693,
    696 (2011).
    14
    conceded facts, were plainly within those boundaries . . . .”);
    see also Rasul v. Bush, 
    542 U.S. 466
    , 485 (2004) (limiting its
    holding to only “[w]hat is presently at stake” before the
    Court). It is first and foremost a conviction we are reviewing.
    When considering the particular record before us, it shows
    that the government proved Bahlul joined a conspiracy to
    murder Americans prior to the September 11, 2001 attacks,
    remained a member following those attacks, and himself
    committed overt acts in furtherance of the conspiracy both
    before and after September 11, 2001. See App. 116-17. As
    tantamount to a Pinkerton conviction, it does not raise the
    concerns that have caused critics to reject the prosecution of
    inchoate conspiracy as a violation of international law. The
    charge was not overbroad, the commission was never
    instructed that the acts or intentions of Bahlul’s co-
    conspirators should be deemed his acts or intentions, there
    was a completed offense, and Bahlul admitted that he himself
    committed several overt acts in furtherance of the completed
    offense. See Al Bahlul v. United States, 
    767 F.3d 1
    , 7 (D.C.
    Cir. 2014) (en banc). His conviction is very much the
    opposite of the “overbroad application of the conspiracy
    principle . . . [that] drag[s] innocent people into the
    prosecution’s net.” Br. of Amici Curiae Int’l Law Scholars 6
    (quoting Telford Taylor, Anatomy of the Nuremberg Trials: A
    Personal Memoir 553 (1992)).
    ***
    When I look at what Bahlul was really convicted of, I see
    a war crime. Thus, his conviction does not violate the law of
    nations, or our separation of powers – even under a de novo
    standard. I further concur with rejecting Bahlul’s additional
    constitutional challenges on the bases set forth in section IV
    of Judge Millet’s opinion. For these reasons we should affirm
    the conviction.
    ROGERS, TATEL, and PILLARD Circuit Judges, dissenting:
    When confronted with the facts of this case, one is tempted to
    search for a way to sustain Ali Hamza Ahmad Suliman al
    Bahlul’s conviction for the crime of inchoate conspiracy to
    violate the laws of war. After all, he has admitted that he
    swore an oath of loyalty to Osama bin Laden, served as bin
    Laden’s personal secretary, and made al Qaeda recruitment
    videos. But tempting as it may be, too much is at stake to
    affirm. The prosecution of al Bahlul in a law-of-war military
    commission for inchoate conspiracy infringes the judiciary’s
    power to preside over the trial of all crimes, as set forth in
    Article III of the Constitution. History and precedent have
    established a narrow, atextual exception to Article III under
    which the military may try enemy belligerents for offenses
    against the international “laws of war,” but inchoate
    conspiracy is not such an offense.
    The challenges of the war on terror do not necessitate
    truncating the judicial power to make room for a new
    constitutional order. “The laws and Constitution are designed
    to survive, and remain in force, in extraordinary times.
    Liberty and security can be reconciled; and in our system they
    are reconciled within the framework of the law.” Boumediene
    v. Bush, 
    553 U.S. 723
    , 798 (2008). The exceptional authority
    the government seeks here falls outside the bounds
    established by more than a century of constitutional practice.
    Equally important, the government here has never contended
    that such authority is even necessary. The prosecution could
    have charged al Bahlul with recognized war crimes using
    conspiracy as a theory of liability or it could have charged
    him before an Article III court with inchoate conspiracy and
    any number of other crimes triable there but it chose neither
    course. The circumstances of this case thus present no
    occasion for the judicial branch to abandon its responsibility
    to enforce the constitutional plan of separated powers.
    2
    Accordingly, for the reasons set forth below, we
    respectfully dissent from the judgment affirming al Bahlul’s
    conviction. We begin in Part I with the standard of review,
    concluding—along with the majority of this court—that al
    Bahlul’s separation-of-powers claim is properly reviewed de
    novo. In Part II we set forth the relevant precedent governing
    that claim, explaining that it fails to provide support for the
    government’s prosecution of al Bahlul in a military
    commission for the crime of inchoate conspiracy. We also
    respond to the government’s key arguments for upholding al
    Bahlul’s conspiracy conviction, finding none persuasive.
    Part III then responds to several of our colleagues’ arguments,
    and Part IV addresses the potential consequences of the
    government’s asserted authority. We conclude by
    emphasizing that, in keeping with our Constitution’s
    commitment to judicial independence, a majority of this court
    declines to cede the requested judicial authority to the
    military.
    I.
    As a threshold matter, the government argues that during
    the military commission proceedings, al Bahlul failed to raise
    each of the challenges he now advances against his
    conspiracy conviction and that he has, therefore, forfeited
    them. Resp’t’s Br. 17–18; see Millett Op. at 8–11. If al Bahlul
    did forfeit them, this court would ordinarily review those
    claims only for plain error—a highly deferential standard. See
    Al Bahlul v. United States (Al Bahlul I), 
    767 F.3d 1
    , 9–10
    (D.C. Cir. 2014) (en banc). The challenge we address,
    however, asks whether trying al Bahlul for the crime of
    inchoate conspiracy in a law-of-war military commission
    violates the separation-of-powers principles enshrined in
    Article III, § 1 of the Constitution. That question warrants de
    novo review.
    3
    As this court has recognized, a party can waive or forfeit
    the argument that an opposing party has waived or forfeited a
    claim. See, e.g., Solomon v. Vilsack, 
    763 F.3d 1
    , 13 (D.C. Cir.
    2014) (“By failing to argue forfeiture or a failure to properly
    plead the claims before the district court, the Secretary has—
    in a word—forfeited his forfeiture argument here.”); United
    States v. Delgado-Garcia, 
    374 F.3d 1337
    , 1340 (D.C. Cir.
    2004) (holding that, by failing to advance it, the government
    had “waived its waiver argument”). Here, the government has
    undoubtedly forfeited any argument it might have had that al
    Bahlul failed to pursue (and thereby forfeited) his “structural”
    Article III claim. In its first en banc brief to this court, the
    government forcefully argued that al Bahlul had forfeited his
    ex post facto challenge by failing to raise it at trial and that
    the challenge was consequently subject to plain error review.
    Brief for the United States 63, Al Bahlul I, 
    767 F.3d 1
    (No. 11-1324), 
    2013 WL 3479237
    , at *63. But the
    government never suggested that al Bahlul had similarly
    forfeited his Article III objection or that this court should
    review that claim only for plain error. 
    Id. at 70–71.
    That was
    so even though al Bahlul had expressly sought de novo review
    of that claim. See Brief for Petitioner 13, Al Bahlul I, 
    767 F.3d 1
    (No. 11-1324), 
    2013 WL 2325912
    , at *13. Later, on remand
    to the original panel, the government again failed to argue that
    al Bahlul had forfeited his structural Article III claim. Instead,
    it expressed its belief that the claim was nonforfeitable and
    thus subject to de novo review. See Transcript of Oral
    Argument at 29–30, Al Bahlul v. United States (Al Bahlul II),
    
    792 F.3d 1
    (D.C. Cir. 2015) (No. 11-1324) (“Q: Are you also
    saying that the structural Article 3 claim is forfeitable? A: I
    am saying that argument is not forfeitable.”). Now, after four
    years of litigation before this court, the government changes
    its tune and, for the very first time, argues that al Bahlul
    forfeited the structural claim at trial. Because the government
    4
    long ago “forfeited [its] forfeiture argument” with respect to
    that claim, 
    Solomon, 763 F.3d at 13
    , this court properly
    reviews it de novo. See Kavanaugh Op. at 3 n.1.
    Even if the government had, from the outset, pressed its
    view that al Bahlul forfeited his structural Article III claim,
    we would still review it de novo. The Supreme Court has
    made clear that ordinary forfeiture and waiver principles do
    not apply to structural Article III claims like this one. As the
    Court has explained, Article III, § 1, which vests “[t]he
    judicial Power of the United States, . . . in one supreme Court,
    and in such inferior Courts as the Congress may from time to
    time ordain and establish,” serves two distinct purposes. First,
    it “safeguard[s] litigants’ right to have claims decided before
    judges who are free from potential domination by other
    branches of government.” Commodity Futures Trading
    Commission v. Schor, 
    478 U.S. 833
    , 848 (1986) (internal
    quotation marks omitted). Second, it “protect[s] the role of the
    independent judiciary within the constitutional scheme of
    tripartite government.” 
    Id. (internal quotation
    marks omitted).
    As with other constitutional rights, litigants can waive or
    forfeit their personal right to an Article III adjudication. See
    
    id. at 848–49;
    Wellness International Network, Ltd. v. Sharif,
    
    135 S. Ct. 1932
    , 1949 (2015) (remanding the case for the
    lower court to determine whether the litigant forfeited his
    personal right to an Article III adjudication). But because the
    provision also protects “institutional interests that the parties
    cannot be expected to protect,” the Supreme Court has held
    that when courts are presented with structural Article III, § 1
    claims, “notions of consent and waiver cannot be dispositive.”
    
    Schor, 478 U.S. at 851
    . Instead, where structural principles
    are implicated, courts may ignore a party’s waiver or
    forfeiture to consider an Article III, § 1 claim de novo. See,
    e.g., 
    id. at 850–57
    (examining whether an Article I tribunal’s
    adjudication of a state law counterclaim impermissibly
    5
    infringed on the judiciary’s domain despite the petitioning
    party having waived his right to pursue the claim in an
    Article III tribunal).
    The Court has repeatedly reaffirmed this approach. In
    Plaut v. Spendthrift Farm, Inc., the Court stated that courts
    have discretion to excuse waivers where parties purport to
    waive “doctrines central to the courts’ structural
    independence” such as res judicata. 
    514 U.S. 211
    , 231–32
    (1995). Most recently, in Wellness International Network v.
    Sharif, the Court demonstrated once again that a litigant’s
    waiver or forfeiture of the “personal right” to an
    Article III adjudication presents no bar to courts’
    consideration of structural Article III claims on the 
    merits. 135 S. Ct. at 1943
    (quoting 
    Schor, 478 U.S. at 850
    ) (emphasis
    added). Despite recognizing that Sharif may have forfeited his
    personal right to have a so-called Stern claim adjudicated
    before an Article III judge, 
    id. at 1941
    n.5, 1949, the Court
    proceeded to consider whether allowing bankruptcy courts to
    adjudicate Stern claims with the parties’ consent would
    “impermissibly threaten the institutional integrity of the
    Judicial Branch,” 
    id. at 1944–46
    (internal quotation marks and
    alteration omitted). Thus, rather than following ordinary rules
    of appellate procedure under which it would have declined to
    review a potentially waived or forfeited claim, the Court
    disregarded the potential forfeiture and considered the
    structural issue on the merits.
    Putting aside whether cases like Schor and Sharif should
    be read to hold that structural Article III, § 1 claims can never
    be waived or forfeited, see Al Bahlul 
    II, 792 F.3d at 3
    –7
    (explaining how the Schor line of cases may be read to
    prohibit waiver or forfeiture of structural Article III claims);
    
    id. at 23–24
    (Tatel, J., concurring) (same), those cases stand,
    at the very least, for the proposition that courts should not
    6
    reflexively apply ordinary rules of waiver and forfeiture to
    dispose of such claims. Instead, under that line of cases,
    courts may exercise their discretion to protect the judiciary’s
    role within our system of government. We believe this is one
    of those cases in which the court should exercise that
    discretion.
    To be sure, al Bahlul is hardly a sympathetic litigant, and
    it is tempting to cut him no slack. Not only has he admitted
    nearly all of the allegations against him, including that he
    pledged an oath of loyalty to Osama bin Laden and produced
    al Qaeda recruiting materials, but during his trial he “flatly
    refused” to put on any defense, conducting a self-styled
    boycott instead. Al Bahlul 
    I, 767 F.3d at 5
    –7, 10. The question
    presented by Schor and its progeny, however, is not whether
    this court should exercise its discretion for al Bahlul’s sake.
    The question is whether the court should exercise its
    discretion to “safeguard[] the role of the Judicial Branch in
    our tripartite system.” 
    Schor, 478 U.S. at 850
    . In our view, the
    answer here is plainly yes.
    As Justice Kennedy observed in Hamdan v. Rumsfeld,
    “[t]rial by military commission raises separation-of-powers
    concerns of the highest order.” 
    548 U.S. 557
    , 638 (2006)
    (Kennedy, J., concurring). Here, al Bahlul presents substantial
    questions as to whether the political branches have invaded
    the judiciary’s domain. Specifically, he argues that Congress
    and the executive branch have ventured beyond the scope of
    the Article III exception for law-of-war military commissions
    sanctioned in Ex parte Quirin, 
    317 U.S. 1
    (1942), a case four
    Justices recently described as “the high-water mark of
    military power to try enemy combatants for war crimes.”
    
    Hamdan, 548 U.S. at 597
    (plurality opinion). Determining
    whether such an expansion of military power is constitutional
    is especially critical as our nation enters a new era in which
    7
    many of the traditional constraints on the political branches’
    authority to prosecute individuals in military commissions—
    including wars’ temporal limits and the presence of clearly
    defined enemies—are dissipating. See, e.g., Legal Issues
    Regarding Military Commissions and the Trial of Detainees
    for Violations of the Law of War: Hearing Before the Senate
    Committee on Armed Services, 111th Cong. 11 (2009)
    (statement of David Kris, Assistant Attorney General,
    National Security Division, Department of Justice) (“In the
    past, military commissions have been associated with a
    particular conflict of relatively short duration. In the modern
    era, . . . the conflict could continue for a much longer time.”).
    In this new context, it is also essential that courts give
    Congress and the President clear guidance on the offenses that
    can be tried by law-of-war military commissions. The purpose
    of such tribunals has long been to “dispense swift justice” in
    the midst of battle. 
    Hamdan, 548 U.S. at 607
    (plurality
    opinion). But in recent years, the uncertainty surrounding the
    legal limits on military commissions has made this form of
    justice anything but swift. Indeed, Congress first codified
    conspiracy as an offense triable by military commission a
    decade ago, and al Bahlul was convicted of inchoate
    conspiracy over seven years ago. Nevertheless, the legitimacy
    of that charge remains in doubt. Because clear limits can
    assist Congress and the Executive as they continue to combat
    al Qaeda and its associated forces and as they consider the
    United States’ role in future conflicts, it would be unwise to
    put off final resolution of the commissions’ authority to
    preside over such charges for still more years to come. Cf. 
    id. at 589
    (majority opinion) (declining the government’s request
    to abstain from reaching the merits of an unlawful enemy
    combatant’s challenge to a military commission’s authority
    because, among other things, he and the government both had
    8
    “a compelling interest in knowing in advance whether [he]
    may be tried by a military commission”).
    Asked at oral argument why the court should not exercise
    its discretion to review this question de novo, the government
    principally argued that constitutional avoidance principles
    counseled against it. See Oral Arg. Tr. 58–60 (Dec. 1, 2015).
    But on that logic, courts would never exercise their discretion
    to consider structural Article III claims because such claims
    always implicate constitutional questions. That outcome
    would stand in direct conflict with the Supreme Court’s
    instruction that a party’s waiver or forfeiture of a structural
    Article III claim not be dispositive as to whether a court
    reaches the claim on the merits.
    Although acknowledging that “Schor affords this court
    some discretion to review a forfeited Article III claim de
    novo,” Millett Op. at 17, Judge Millett would decline to
    exercise that discretion here, 
    id. at 17–27.
    In our view, her
    reasons for doing so insufficiently account for the central
    teaching of Schor and its progeny and overstate the
    consequences of exercising our discretion. In particular,
    although it is true that the Supreme Court has typically
    invoked Schor to ignore a party’s waiver or forfeiture of a
    structural Article III claim in civil cases involving
    adjudicatory systems premised on the parties’ consent—that
    is, in cases where parties necessarily waived their right to
    later challenge the adjudication of their claims in non-
    Article III fora, see 
    id. at 20–21—those
    cases recognize that
    Article III, § 1 protects the judiciary’s role in our system of
    government and that the judiciary cannot be wholly dependent
    on litigants to assert its institutional interests, see, e.g., 
    Schor, 478 U.S. at 851
    . This principle—that there are Article III, § 1
    guarantees that are not the parties’ to waive or forfeit—
    applies at least as strongly in criminal as in civil cases. See
    9
    Peretz v. United States, 
    501 U.S. 923
    , 925, 937–39 (1991)
    (acknowledging in the context of a criminal case that, under
    Schor, there may be structural principles litigants cannot
    waive or forfeit); 
    id. at 950
    (Marshall, J., dissenting)
    (“Although parties may waive their personal guarantee of an
    independent Article III adjudicator, parties may not waive
    Article III’s structural guarantee.” (internal citation omitted)).
    For similar reasons, Judge Millett’s concern that the court
    not “reward[]” al Bahlul for his refusal to participate in the
    military proceedings and that excusing al Bahlul’s forfeiture
    would undermine the judicial process, Millett Op. at 21,
    misses the point. As already noted, the court, in exercising its
    discretion to consider the matter de novo, is doing so for the
    judicial branch’s own benefit, not for al Bahlul’s. And
    although enforcing forfeitures generally ensures timely raised
    objections, deters sandbagging of the other party, and enables
    timely fact-finding and error correction, see 
    id. at 9–10,
    those
    concerns are not compelling here because future litigants will
    have no way of knowing in advance whether courts will
    exercise their discretion to consider structural Article III
    claims. Moreover, any disruption to normal appellate process,
    see 
    id. at 21–22,
    is “plainly insufficient to overcome the
    strong interest of the federal judiciary in maintaining the
    constitutional plan of separation of powers.” Glidden Co. v.
    Zdanok, 
    370 U.S. 530
    , 536 (1962); see Kuretski v.
    Commissioner of Internal Revenue Service, 
    755 F.3d 929
    , 936
    (D.C. Cir. 2014).
    In sum, although the government now claims that al
    Bahlul forfeited his personal right to a trial in an Article III
    court, it conceded otherwise at every prior stage of this
    litigation, thereby “forfeiting the forfeiture.” In any event,
    strong reasons counsel in favor of exercising our discretion to
    consider the matter de novo. We therefore ask whether
    10
    Congress has, in the Military Commissions Act of 2006,
    impermissibly encroached on the province of Article III
    courts by authorizing law-of-war military commissions to try
    alien unlawful enemy combatants for the crime of conspiracy.
    On that question, too, we think the answer is clear: it has.
    II.
    By its text, Article III commits the entire “judicial Power
    of the United States” to the Supreme Court and “such inferior
    Courts as the Congress may from time to time ordain and
    establish.” U.S. CONST. art. III, § 1. It further provides that
    “[t]he judicial Power shall extend to all Cases, in Law and
    Equity, arising under th[e] Constitution, the Laws of the
    United States, and Treaties made, or which shall be made,
    under their Authority,” 
    id. § 2,
    cl. 1; that the judges who sit on
    Article III courts shall enjoy life tenure and salary protections,
    
    id. § 1;
    and that “[t]he Trial of all Crimes, except in Cases of
    Impeachment, shall be by Jury,” 
    id. § 2,
    cl. 3.
    Over time, the Supreme Court has recognized certain
    limited exceptions, based on principles “rooted in history and
    the Constitution,” Northern Pipeline Construction Co. v.
    Marathon Pipe Line Co., 
    458 U.S. 50
    , 74 (1982) (plurality
    opinion), to Article III’s commitment of the judicial power to
    constitutional courts and the judge and jury protections that
    go along with it. Thus, Congress may create non-Article III
    courts to try cases in the District of Columbia and U.S.
    territories. Palmore v. United States, 
    411 U.S. 389
    , 390–91
    (1973); American Insurance Co. v. 356 Bales of Cotton, 26
    U.S. (1 Pet.) 511, 546 (1828); see U.S. CONST. art. I, § 8,
    cl. 17. It may assign to administrative agencies the
    adjudication of private disputes involving “public rights”
    stemming from federal regulatory programs. Murray’s Lessee
    v. Hoboken Land & Improvement Co., 59 U.S. (18 How.) 272,
    11
    284 (1855); see U.S. CONST. art. I, § 8, cl. 1. It may also
    assign certain criminal prosecutions of individuals connected
    to military service to courts martial. Dynes v. Hoover, 61 U.S.
    (20 How.) 65, 79 (1857); see U.S. CONST. art I, § 8, cl. 14.
    Finally, at issue here, the Supreme Court has upheld a narrow
    Article III carve-out for military commissions. See 
    Quirin, 317 U.S. at 39
    –41.
    Historically, the government has established military
    commissions in three situations in which wartime necessity
    has required them: First, it has established commissions to
    operate as general courts in areas under martial law. See Ex
    parte Milligan, 71 U.S. (4 Wall.) 2, 127 (1866) (recognizing
    that “there are occasions when martial rule can be properly
    applied”). Second, the government has employed military
    commissions as general courts in areas that the military
    temporarily occupies. See Madsen v. Kinsella, 
    343 U.S. 341
    (1952) (upholding a military commission’s jurisdiction to try
    a civilian for murder in occupied Germany). Third, the
    government has created commissions to punish enemy
    belligerents who commit offenses against the laws of war
    during an armed conflict. See Quirin, 
    317 U.S. 1
    ; see also
    
    Hamdan, 548 U.S. at 595
    –97 (plurality opinion); WILLIAM
    WINTHROP, MILITARY LAW AND PRECEDENTS 836–40 (rev. 2d
    ed. 1920) [hereinafter WINTHROP, MILITARY LAW].
    The parties agree that al Bahlul was tried before the third
    type of tribunal—that is, a law-of-war military commission.
    They part ways, however, in defining the permissible scope of
    those commissions’ jurisdiction. Al Bahlul contends that law-
    of-war military commissions may try only offenses against
    the international laws of war, and that the sole remaining
    charge here, the standalone crime of conspiracy, is not such
    an offense. The government responds to al Bahlul’s
    constitutional challenge in two ways. First, it contends that
    12
    Congress may authorize military commissions to try enemy
    belligerents for violations of the international laws of war as
    well as any other offenses Congress defines as violations of
    the “laws of war.” Following from this point, the government
    asserts that although conspiracy to commit war crimes is not
    recognized as an international law-of-war offense, Congress
    in the Military Commissions Act of 2006 lawfully vested
    military commissions with authority to try individuals like al
    Bahlul for the crime of conspiracy. In doing so, the
    government takes the position that international law imposes
    no constraints on the kinds of offenses Congress can make
    triable by military commission. Alternatively, the government
    takes the slightly narrower position that the military can try
    enemy belligerents for international war crimes, as well as
    any offenses punishable under a “U.S. common law of war,”
    by which the government means any offenses traditionally
    tried by military commission in the United States. On this
    point, the government contends that there is sufficient
    historical precedent for trying conspiracy before law-of-war
    military commissions, and that the charge against al Bahlul
    was, therefore, lawful. Based on the Supreme Court precedent
    most directly on point—which we, as a lower court, must
    follow—al Bahlul has the better of these arguments.
    A.
    The principal decision that governs here is Ex parte
    Quirin, a case in which seven Nazi saboteurs challenged the
    government’s authority to try them in a military, as opposed
    to civilian, tribunal. Prior to their arrests, the saboteurs had
    received military training at a sabotage school in Germany,
    traveled to the United States by submarine, discarded their
    military uniforms once ashore, and then traveled to various
    locales in civilian dress with the apparent intent to destroy
    U.S. war industries and 
    facilities. 317 U.S. at 21
    . After they
    13
    were apprehended and detained, President Roosevelt issued
    an executive order establishing a military commission to try
    them for offenses against the laws of war and the Articles of
    War. 
    Id. at 22.
    Pursuant to that order, the Army Judge
    Advocate General prepared four charges against the
    saboteurs, which read as follows:
    1. Violation of the law of war.
    2. Violation of Article 81 of the Articles of War,
    defining the offense of relieving or attempting to
    relieve, or corresponding with or giving intelligence
    to, the enemy.
    3. Violation of Article 82, defining the offense of
    spying.
    4. Conspiracy to commit the offenses alleged in
    charges 1, 2 and 3.
    
    Id. at 23.
    Focusing on the first charge alone, the Supreme Court
    upheld the commission’s jurisdiction to try the defendants. It
    observed that “[a]n important incident to the conduct of war is
    the adoption of measures by the military command not only to
    repel and defeat the enemy, but to seize and subject to
    disciplinary measures those enemies who in their attempt to
    thwart or impede our military effort have violated the law of
    war.” 
    Id. at 28–29.
    It further found that Congress had
    authorized the use of law-of-war military commissions in
    Article 15 of the Articles of War. Article 15 directed that “the
    provisions of the[] articles conferring jurisdiction upon
    courts-martial shall not be construed as depriving military
    commissions . . . of concurrent jurisdiction in respect of
    offenders or offenses that by statute or by the law of war may
    be triable by such military commissions.” 
    Id. at 27–28
                                   14
    (emphasis added). By enacting that provision, the Court
    explained, Congress had
    exercised its authority to define and punish offenses
    against the law of nations by sanctioning, within
    constitutional limitations, the jurisdiction of military
    commissions to try persons for offenses which,
    according to the rules and precepts of the law of
    nations, and more particularly the law of war, are
    cognizable by such tribunals.
    
    Id. at 28.
    Stating that the term “law of war” refers to a “branch of
    international law,” 
    id. at 29
    (emphasis added); see also 
    id. at 27–28,
    the Court proceeded to consider whether the
    defendants had been charged with a violation of the
    international rules governing armed conflicts, 
    id. at 30–31,
    35–36. It ultimately concluded that they had been, expressing
    its belief that passing behind enemy lines in civilian dress
    with the purpose of committing hostile acts was then an
    offense under international law. 
    Id. at 31.
    According to the
    Court, the “precept” that “those who during time of war pass
    surreptitiously from enemy territory into our own, discarding
    their uniforms upon entry, for the commission of hostile acts
    involving destruction of life or property, [are] . . . punishable
    . . . by military commission” was “so recognized in practice
    both here and abroad” and “so generally . . . accepted as valid
    by authorities on international law” that it had to be “regarded
    as a rule or principle of the law of war recognized by this
    Government by its enactment of the Fifteenth Article of War.”
    
    Id. at 35–36.
    After concluding that Congress had lawfully authorized
    the military-commission trial of the offense specified in the
    15
    first charge, the Court turned to consider whether, despite
    Congress’s authorization, the jury trial protections in
    Article III, § 2 and the Fifth and Sixth Amendments
    nonetheless barred the saboteurs’ prosecution in a military
    commission. Concluding that they did not, the Court
    emphasized that military tribunals “are not courts in the sense
    of the Judiciary Article,” 
    id. at 39,
    and that the adoptions of
    Article III, § 2 and the Fifth and Sixth Amendments were in
    no way intended to deprive the military of its traditional
    ability to try enemy belligerents for offenses against the laws
    of war, 
    id. at 39–41.
    Violations of the laws of war, the Court
    observed, have, “since the founding of our government,” been
    cognizable by military tribunals. 
    Id. at 41.
    For support, the
    Court pointed to an 1806 statute subjecting alien spies to
    death, “according to the law and usage of nations, by sentence
    of a general court martial.” 
    Id. at 41.
    That statute, the Court
    explained, provided a “contemporary construction of both
    Article III, § 2, and the Amendments as not foreclosing trial
    by military tribunals, without a jury, of offenses against the
    law of war committed by enemies not in or associated with
    our Armed Forces.” 
    Id. at 41.
    Thus, in Quirin the Supreme
    Court recognized an exception to Article III and its judge and
    jury protections for military trials of violations of the “laws of
    war”—a body of law that, as noted above, the Court described
    as international. 
    Id. at 29.
    For over seventy years, the Court has treated the phrase
    “law of war” as referring to a body of international law, thus
    reinforcing the idea that Quirin recognized an Article III
    exception for international law-of-war offenses. For instance,
    only four years after Quirin, in In re Yamashita, 
    327 U.S. 1
    (1946), the Court, reaffirming Quirin’s “governing
    principles,” 
    id. at 9,
    considered whether a military
    commission could try a Japanese Commanding General for
    the “plain violations of the law of war” committed by his
    16
    troops, based on a command theory of responsibility, 
    id. at 16.
    Continuing to rely on the Articles of War as having provided
    congressional authorization for military commissions to try
    enemy combatants for offenses against the “law of war,” 
    id. at 7
    , the Court concluded that the commission had jurisdiction
    over the specified offense, 
    id. at 17–18.
    Importantly for our
    purposes here, the Court looked to international sources to
    determine whether the charges specified offenses against the
    “laws of war.” 
    Id. at 15
    –16.
    Four years later, the Court again addressed the scope of
    law-of-war military commissions’ jurisdiction in Johnson v.
    Eisentrager, 
    339 U.S. 763
    (1950). The Court reiterated the
    principles laid out in Quirin and Yamashita, observing that
    “[t]he jurisdiction of military authorities, during or following
    hostilities, to punish those guilty of offenses against the laws
    of war is long-established.” 
    Id. at 786
    (emphasis added). It
    again looked only to international sources to conclude that the
    conduct with which the petitioners were charged—“[b]reach
    of the terms of an act of surrender”—violated the
    international laws governing armed conflicts. 
    Id. at 787–88.
    Quirin, as reinforced by Yamashita and Eisentrager, thus
    upheld the authority of military commissions to try enemy
    belligerents for violations of the international laws of war
    without running afoul of Article III. But those cases went no
    further. And while it is true that those cases did not address
    the question presented here—i.e., whether military
    commissions can exercise jurisdiction over crimes
    unrecognized under international law without offending
    Article III’s structural principles—we, as a lower court,
    should be hesitant to stretch the exception recognized in those
    cases in the ways the government suggests. For one thing, a
    Supreme Court plurality has already described Quirin as “the
    high-water mark of military power to try enemy combatants
    17
    for war crimes.” 
    Id. at 597.
    For another, law-of-war military
    commissions present an atextual exception to Article III’s
    vesting of the judicial power in civilian courts, requiring that
    we construe the exception narrowly. Finally, expanding the
    scope of military commissions’ jurisdiction would erode their
    historical and theoretical underpinnings as an important
    mechanism for punishing enemy combatants who fail to abide
    by the internationally agreed upon rules governing the
    conduct of war.
    B.
    Given the foregoing principles, the Article III inquiry in
    this case turns on whether conspiracy to commit war crimes is
    an offense under the international laws of war. As the
    government candidly and rightly concedes, it is not. See Brief
    for the United States 34, Al Bahlul I, 
    767 F.3d 1
    (No. 11-
    1324), 
    2013 WL 3479237
    , at *34 (“[T]he government has
    acknowledged that conspiracy has not attained recognition at
    this time as an offense under customary international law.
    This is true even when the objects of the conspiracy are
    offenses prohibited by customary international law, as some
    of them are in this case.” (internal citation omitted)); see also
    Government Response to Defense Motion to Dismiss for Lack
    of Lack of [sic] Jurisdiction Over the Charge of Conspiracy,
    AE048A, at 21–22, United States v. Al-Nashiri (M.C. Mar.
    26, 2012) (“[H]istory reflects a lack of international
    consensus for treating the standalone offense of conspiracy as
    a war crime as a matter of customary international law . . . .”
    (emphasis omitted)).
    To begin, neither the Hague nor the Geneva
    Conventions—“the major treaties on the law of war,”
    
    Hamdan, 548 U.S. at 604
    (plurality opinion)—mention
    conspiracy, see Convention with Respect to the Laws and
    18
    Customs of War on Land (Hague II), July 29, 1899, 32 Stat.
    1803; Convention Respecting the Laws and Customs of War
    on Land (Hague IV), Oct. 18, 1907, 36 Stat. 2277; Geneva
    Convention for the Amelioration of the Condition of the
    Wounded and Sick in Armed Forces in the Field, Aug. 12,
    1949, 6 U.S.T. 3114, 75 U.N.T.S. 31; Geneva Convention for
    the Amelioration of the Condition of Wounded, Sick and
    Shipwrecked Members of Armed Forces at Sea, Aug. 12,
    1949, 6 U.S.T. 3217, 75 U.N.T.S. 85; Geneva Convention
    Relative to the Treatment of Prisoners of War, Aug. 12, 1949,
    6 U.S.T. 3316, 75 U.N.T.S. 135; Geneva Convention Relative
    to the Protection of Civilian Persons in Time of War, Aug. 12,
    1949, 6 U.S.T. 3516, 75 U.N.T.S. 287; Protocol Additional to
    the Geneva Conventions of 12 August 1949, and Relating to
    the Protection of Victims of International Armed Conflicts
    (Protocol I), June 8, 1977, 1125 U.N.T.S. 3; Protocol
    Additional to the Geneva Conventions of 12 August 1949,
    and Relating to the Protection of Victims of Non-International
    Armed Conflicts (Protocol II), June 8, 1977, 1125 U.N.T.S.
    609.
    International tribunals established for the prosecution of
    war crimes, crimes against humanity, and crimes against
    peace have also declined to recognize conspiracy as a war
    crime. For instance, the London Charter, which established
    the International Military Tribunal at Nuremberg for the
    prosecution of major Nazi war criminals after World War II,
    did not list conspiracy among the punishable war crimes. See
    Agreement for the Prosecution and Punishment of the Major
    War Criminals of the European Axis, Aug. 8, 1945, 82
    U.N.T.S. 279 (London Charter). Indeed, the tribunal
    dismissed a charge for conspiracy to commit war crimes and
    crimes against humanity because “the Charter d[id] not define
    as a separate crime any conspiracy except the one to commit
    acts of aggressive war.” 22 TRIAL OF THE MAJOR WAR
    19
    CRIMINALS BEFORE THE INTERNATIONAL MILITARY TRIBUNAL
    469 (1948).
    The same is true of the charter for the International
    Military Tribunal for the Far East, see Supreme Commander
    for the Allied Powers at Tokyo, General Order No. 20,
    Special Proclamation for the Establishment of an International
    Military Tribunal for the Far East, Apr. 26, 1946, T.I.A.S. No.
    1589, 4 Bevans 20; International Military Tribunal for the Far
    East, Judgment of 4 November 1948, in 22 THE TOKYO WAR
    CRIMES TRIAL: THE COMPLETE TRANSCRIPTS OF THE
    PROCEEDINGS OF THE INTERNATIONAL MILITARY TRIBUNAL
    FOR THE FAR EAST 48,448–51 (R. John Pritchard and Sonia
    M. Zaide eds. 1981), and the law conferring authority on the
    forces occupying post-war Germany to punish lower-level
    Nazi officials for war crimes, see, e.g., 2 TRIALS OF WAR
    CRIMINALS BEFORE THE NURENBERG MILITARY TRIBUNALS
    UNDER CONTROL COUNCIL LAW NO. 10, at 122, 174 (1949).
    As a tribunal established under the latter explained, “[N]either
    the Charter of the International Military Tribunal nor Control
    Council Law No. 10 has defined conspiracy to commit a war
    crime or crime against humanity as a separate substantive
    crime; therefore, this Tribunal has no jurisdiction to try any
    defendant upon a charge of conspiracy considered as a
    separate substantive offense.” 
    Id. More recently,
    the statutes for the International Criminal
    Tribunal for the Former Yugoslavia, the International
    Criminal Tribunal for Rwanda, and the Special Court for
    Sierra Leone did not identify conspiracy as a violation of the
    laws of war. See Statute of the International Tribunal for the
    Former Yugoslavia, annexed to Report of the Secretary-
    General Pursuant to Paragraph 2 of Security Council
    Resolution 808 (1993) S/25704 (May 3, 1993), adopted by
    S.C. Res. 827 (May 25, 1993), reprinted in 32 I.L.M. 1159
    20
    [hereinafter ICTY Statute]; Statute of the International
    Tribunal for Rwanda, adopted by S.C. Res. 955, U.N. Doc.
    S/RES/955 (1994), reprinted in 33 I.L.M. 1598 [hereinafter
    ICTR Statute]; Statute of the Special Court for Sierra Leone,
    Jan. 16, 2002, 2178 U.N.T.S. 138. And, quite tellingly, the
    Rome Statute, which established the International Criminal
    Court and which “catalogues an extensive list of international
    war crimes,” Hamdan v. United States, 
    696 F.3d 1238
    , 1251
    (D.C. Cir. 2012), overruled on other grounds, Al Bahlul 
    I, 767 F.3d at 11
    , does not list conspiracy to commit war crimes as
    itself a war crime. See Rome Statute of the International
    Criminal Court, July 17, 1998, 2187 U.N.T.S. 90 [hereinafter
    Rome Statute].
    Other sources on the laws of war likewise recognize that
    international law has declined to adopt conspiracy to commit
    war crimes as a standalone offense. See, e.g., ANDREA
    BIANCHI & YASMIN NAQVI, INTERNATIONAL HUMANITARIAN
    LAW AND TERRORISM 244 (2011); ANTONIO CASSESE,
    INTERNATIONAL CRIMINAL LAW 191, 197 (2003). Domestic
    jurists confirm that international law has long rejected
    conspiracy as a law-of-war offense. Professor George Fletcher
    observes that, “Since 1948 and the residue of the Genocide
    Convention in the statutes of the ad hoc tribunals, every
    relevant international treaty on international humanitarian law
    or international criminal law had deliberately avoided the
    concept and language of conspiracy.” George P. Fletcher,
    Hamdan Confronts the Military Commissions Act of 2006, 45
    COLUM. J. TRANSNAT’L L. 427, 448 (2007). William
    Winthrop, the “Blackstone of military law,” Reid v. Covert,
    
    354 U.S. 1
    , 19 (1957) (plurality opinion), noted that
    conspiracy was not a law-of-war offense. WINTHROP,
    MILITARY 
    LAW, supra, at 842
    , cited in 
    Hamdan, 548 U.S. at 597
    . Where Winthrop listed the law-of-war violations that had
    21
    principally been charged in U.S. military commissions,
    conspiracy was not among them. See 
    id. at 839–40.
    Significantly for the issue before us, international law has
    adopted conspiracy as a standalone offense in only two
    circumstances. First, it has recognized conspiracy to commit
    genocide as a crime against humanity. See, e.g., Convention
    on the Prevention and Punishment of the Crime of Genocide,
    art. 3(b), Dec. 9, 1948, 78 U.N.T.S. 277; ICTY Statute, supra,
    art. 4; ICTR Statute, supra, art. 2. Second, it has
    acknowledged conspiracy to wage aggressive war as a crime
    against peace. See London Charter, art. 6(a). Outside of these
    two contexts, however, the crime of conspiracy has gained no
    traction in international law. 
    Hamdan, 548 U.S. at 610
    (plurality opinion). Those exceptions are plainly not at issue
    here, for al Bahlul was charged with neither.
    The limited international acceptance of conspiracy is not
    due to a lack of consideration. For instance, during
    negotiations over the London Charter in 1945, the concept of
    conspiracy as a separate offense generated considerable
    debate. See BRADLEY F. SMITH, REACHING JUDGMENT AT
    NUREMBERG 51 (1977); ROBERT H. JACKSON, REPORT OF
    UNITED STATES REPRESENTATIVE TO THE INTERNATIONAL
    CONFERENCE ON MILITARY TRIALS, at vii (1947) (“Another
    point on which there was a significant difference of viewpoint
    concerned the principles of conspiracy as developed in Anglo-
    American law, which are not fully followed nor always well
    regarded by Continental jurists.”). Although the prosecution,
    led by Justice Robert Jackson, charged the defendants with
    conspiracy to commit war crimes and crimes against
    humanity, the tribunal rebuffed the effort, see 22 TRIALS OF
    THE MAJOR WAR CRIMINALS BEFORE THE INTERNATIONAL
    MILITARY TRIBUNAL 412, 469 (1948); 
    SMITH, supra, at 135
    –
    37, likely due to the controversy surrounding those charges,
    22
    see 
    CASSESE, supra, at 197
    ; 
    SMITH, supra, at 121
    (reporting
    that the lead French judge raised several objections to the
    conspiracy charges, “[b]eginning with the obvious objection
    that the crime of conspiracy was unknown to both continental
    and international law”); see also TELFORD TAYLOR, FINAL
    REPORT TO THE SECRETARY OF THE ARMY ON THE
    NUERNBERG TRIALS UNDER CONTROL COUNCIL LAW NO. 10,
    at 70 n.188, 227 (1949) (speculating that the tribunals
    established in post-war Germany under Control Council Law
    No. 10 rejected charges for conspiracy to commit war crimes
    and crimes against humanity because of “the hostility of the
    French (and probably Soviet) judges to the concept of
    conspiracy” and recounting that during the proceedings under
    the London Charter “many European jurists view[ed] the
    Anglo-Saxon concept of criminal conspiracy with deep
    suspicion”). Indeed, after returning from Nuremberg, even
    Justice Jackson wrote approvingly of the “more
    discriminating principles upon which to prosecute criminal
    gangs, secret associations and subversive syndicates” that he
    had learned of from British, French, Soviet, and German
    lawyers. Krulewitch v. United States, 
    336 U.S. 440
    , 450
    (1949) (Jackson, J., concurring).
    To take a more recent example, during negotiations over
    the Rome Statute for the International Criminal Court, the
    concept of conspiracy again presented a “very divisive issue.”
    Per Saland, International Criminal Law Principles in THE
    INTERNATIONAL CRIMINAL COURT: THE MAKING OF THE
    ROME STATUTE 189, 199 (Roy S. Lee ed., 1999). At least one
    proposal would have made conspiracy to commit any of the
    other substantive crimes a punishable offense. See 2 Report of
    the Preparatory Committee on the Establishment of an
    International Criminal Court, U.N.GAOR, 51st Sess., Supp.
    No. 22A, at 94–95, U.N. Doc. A/51/22 (1996), reprinted in
    M. CHERIF BASSIOUNI, THE STATUTE OF THE INTERNATIONAL
    23
    CRIMINAL COURT: A DOCUMENTARY HISTORY 489–90 (1998).
    But the final statute did not incorporate the idea. See Rome
    Statute. It appears that conspiracy was ultimately excluded as
    a substantive offense because of “conceptual differences
    concerning conspiracy among the different legal systems” and
    because of a belief among some that inchoate conspiracy
    should be punishable only when its object is an “exceptionally
    serious crime.” 2 Report of the Preparatory 
    Committee, supra, at 95
    ; see also, e.g., Rapporteur for the Preparatory
    Committee on the Establishment of an International Criminal
    Court, Summary of the Proceedings of the Preparatory
    Committee During the Period 25 March–12 April 1996, at
    75–77, A/AC.249/1 (May 7, 1996) (reporting a Japanese
    proposal to exclude punishment for conspiracy except where
    it relates to “exceptionally serious offences,” for which “it
    may be necessary to punish a conduct of plot or preparation
    before the commencement of the execution of a crime”).
    The emphasis that international tribunals have placed on
    distinguishing concepts like joint criminal enterprise as a
    liability theory from the standalone crime of conspiracy
    further demonstrates conspiracy’s lack of acceptance within
    international law. For example, in rejecting a challenge to the
    prosecution’s ability to charge a defendant with substantive
    offenses like murder on a joint criminal enterprise theory of
    liability—a concept discussed in greater detail below—the
    Appeals Chamber for the International Criminal Tribunal for
    the Former Yugoslavia stressed: “Criminal liability pursuant
    to a joint criminal enterprise is not a liability for mere
    membership or for conspiring to commit crimes, but a form of
    liability concerned with the participation in the commission of
    a crime as part of a joint criminal enterprise, a different
    matter.” Prosecutor v. Milutinović, Case No. IT-99-37-AR72,
    Decision on Dragoljub Ojdanić’s Motion Challenging
    Jurisdiction—Joint Criminal Enterprise, ¶ 26 (Int’l Crim.
    24
    Trib. for the Former Yugoslavia, Appeals Chamber, May 21,
    2003).
    In sum, conspiracy to violate the laws of war is not a
    punishable offense under international law. Cf. 
    Hamdan, 696 F.3d at 1249
    –51 (looking to similar sources to conclude that
    material support for terrorism is not a violation of the
    international laws of war). Indeed, not only has the
    government conceded as much, but a plurality of the Supreme
    Court has already so found. See 
    Hamdan, 548 U.S. at 610
    (plurality opinion). Accordingly, Congress cannot vest
    military commissions with jurisdiction to try enemy
    combatants for that offense without running afoul of
    Article III.
    C.
    With inchoate conspiracy lying beyond the reach of any
    accepted understanding of the international laws of war, the
    government offers a different interpretation of Quirin and
    other relevant precedents. Its arguments are unpersuasive.
    First, the government insists that Quirin itself
    demonstrates that the atextual Article III exception for
    military trials of “law of war” offenses extends to purely
    domestic war crimes. In support, it claims that “spying and
    the kindred offense of sabotage”—the offenses the Court
    examined in Quirin—were not, and have never been, offenses
    against the international laws of war. Resp’t’s Br. 44–45; see
    Kavanaugh Op. at 9–12 & nn.6–7. In its view, this shows that
    the “law of war” to which the Court referred in carving out an
    Article III exception includes purely domestic offenses.
    The greatest flaw in the government’s argument is that
    the Court expressly identified the “law of war” as a branch of
    25
    international law. See 
    Quirin, 317 U.S. at 2
    9. That definition
    was consistent with the widely recognized understanding of
    that term. See, e.g., WINTHROP, MILITARY 
    LAW, supra, at 773
    (defining the law of war as a “branch of International Law”);
    Laws of War, BLACK’S LAW DICTIONARY (3d ed. 1933)
    (“This term denotes a branch of public international law, and
    comprises the body of rules and principles observed by
    civilized nations for the regulation of matters inherent in, or
    incidental to, the conduct of a public war . . . .”). It was also
    consistent with the Quirin parties’ understanding of the term.
    See Brief for the United States 29, Quirin, 
    317 U.S. 1
    (describing the “law of war” as a “centuries-old body of
    largely unwritten rules and principles of international law
    which governs the behavior of both soldiers and civilians
    during time of war” (citing, inter alia, WINTHROP, MILITARY
    
    LAW, supra, at 773
    )); Brief for Petitioners 28, Quirin, 
    317 U.S. 1
    (“[T]he alleged Law of War which is asserted by the
    prosecution is a species of international law analogous to
    common law.”). Had the Court thought that the term actually
    encompassed a domestic “common law of war,” it likely
    would have said as much. Thus, we should apply Quirin’s
    Article III exception for military trials of “law of war”
    offenses as the Quirin Court defined it—that is, as an
    exception for military trials of those who violate the
    internationally agreed upon rules governing armed conflict.
    But the government’s argument suffers from yet another
    major flaw—the Supreme Court’s analysis makes clear that it
    viewed “spying and the kindred offense of sabotage” as
    offenses against the international laws of war. The Court
    began its analysis from the premise that Congress had
    authorized the use of military commissions for “offenders or
    offenses against the law of war,” 
    Quirin, 317 U.S. at 2
    8,
    which, as noted above, the Court identified as a “branch of
    international law,” 
    id. at 29
    ; see Part 
    II.A, supra
    . Thus, when
    26
    it concluded that Congress had vested military commissions
    with jurisdiction over the offense of having passed behind
    enemy lines with the intent to commit espionage or sabotage,
    see 
    Quirin, 317 U.S. at 35
    –36, it implicitly concluded that
    those offenses violated the international laws of war.
    Further to the point, in analyzing the charge, the Court
    looked to “[a]uthorities on International Law” who “regarded
    as war criminals” saboteurs who passed behind enemy lines
    without uniform, 
    id. at 35
    n.12, and it relied on international
    sources to establish that the offense was, “[b]y universal
    agreement and practice,” recognized as an international law
    violation, 
    id. at 30
    & n.7, 31 n.8, 35 n.12. It also quoted early
    statutes and military proceedings that appeared to identify
    spying as punishable by military tribunal according to the
    “law and usage of nations”—that is, according to international
    practice. 
    Id. at 31
    n.9, 41. Accordingly, although the
    government points to scholarly criticism of the Court’s
    treatment of spying, see Resp’t’s Br. 33–35, we are bound by
    the Court’s own analysis, which was premised on the
    understanding that spying and sabotage were international
    law-of-war offenses. See 
    Quirin, 317 U.S. at 35
    –36.
    The government pushes back, pointing out that Quirin
    surveyed American historical practice in determining whether
    the conduct described in the first charge constituted a
    violation of the “law of war.” In its view, this shows that the
    Court believed that the “law of war” encompassed domestic
    offenses. But, once again, the Court in Quirin expressly
    defined the law of war as a body of international law. 
    Quirin, 317 U.S. at 2
    8–29. It would have been strange for the Court to
    have defined it as such if it understood that it also
    encompassed a domestic body of law. Considered in its
    proper context, then, Quirin’s analysis of domestic precedents
    for trying spying and sabotage reflect an effort to confirm that
    27
    our law did not preclude a military trial for the specified
    offense. That is, the Court referred to U.S. cases to discern
    potential domestic limits on the prosecution of law-of-war
    offenses. The Court explained that there might be offenses
    that
    would not be triable by military tribunal here, either
    because they are not recognized by our courts as
    violations of the law of war or because they are of that
    class of offenses constitutionally triable only by a jury.
    
    Id. at 29;
    see 
    id. (citing, as
    an example of the latter, Ex parte
    Milligan, 71 U.S. (4 Wall.) 2). The government’s position
    gains no support from Hamdan’s consideration of domestic
    precedents in determining whether inchoate conspiracy
    qualified as a violation of the “law of war,” as that term is
    used in 10 U.S.C. § 821. The plurality looked to domestic
    precedent in just the same way the Quirin Court had: as a
    potential limitation on military-commission jurisdiction. See
    
    Hamdan, 548 U.S. at 603
    , 610 (plurality opinion); Al
    Bahlul 
    II, 792 F.3d at 8
    –9; 
    id. at 25–26
    (Tatel, J., concurring).
    The government next argues that Article III must be
    construed in light of Congress’s Article I powers and that
    those powers enable Congress to go beyond international law
    in determining the offenses triable by military commission. In
    support, the government notes that Quirin and its progeny
    indicate that Congress’s power to create military commissions
    derives from its war powers. Resp’t’s Br. 29–30 (citing, inter
    alia, 
    Yamashita, 327 U.S. at 11
    ). It then argues that
    Congress’s power to codify offenses triable by such tribunals
    must stem from those powers as well. Those powers include
    the power to “declare War,” U.S. CONST. art. I, § 8, cl. 11,
    “raise and support Armies,” 
    id. § 8,
    cl. 12, “provide and
    maintain a Navy,” 
    id. § 8,
    cl. 13, “make Rules for the
    28
    Government and Regulation of the land and naval Forces,” 
    id. § 8,
    cl. 14, and “provide for calling forth the Militia,” 
    id. § 8,
    cl. 15. Pointing out that these powers, unlike the define and
    punish power, contain no textual limitation based on
    international law, the government concludes that Congress’s
    power to define offenses triable by military commissions must
    be similarly unconstrained. See Resp’t’s Br. 30–32; see also
    Kavanaugh Op. at 4–19.
    As an initial matter, although it is true that Quirin,
    Yamashita, and Hamdan looked to the war powers in
    discussing congressional authority to establish military
    commissions, see 
    Hamdan, 548 U.S. at 591
    (plurality
    opinion); 
    Yamashita, 327 U.S. at 12
    ; 
    Quirin, 317 U.S. at 2
    6;
    see also 
    WINTHROP, supra, at 831
    (stating that Congress’s
    power “to ‘declare war’ and ‘raise armies’” provided the
    “original sanction” for military commissions), they
    consistently looked to the Define and Punish Clause alone in
    addressing Congress’s authority to confer jurisdiction over
    particular offenses. See 
    Hamdan, 548 U.S. at 601
    –02
    (plurality opinion); 
    Yamashita, 327 U.S. at 7
    ; 
    id. at 26
    (Murphy, J., dissenting); 
    Quirin, 317 U.S. at 2
    8. For instance,
    in Yamashita, the Court explained that “the [military]
    commission derives its existence” from the war 
    powers, 327 U.S. at 12
    (emphasis added), but that its jurisdiction over
    specific offenses comes from Congress’s “exercise of the
    power conferred upon it by Article I, § 8, cl. 10 of the
    Constitution to ‘define and punish * * * Offenses against the
    Law of Nations * * *,’ of which the law of war is a part.” 
    Id. at 7
    (alteration in original). Winthrop endorsed this
    distinction, stating that Civil War-era legislation subjecting
    “spies and guerillas” to military jurisdiction “may be regarded
    as deriving its authority from” the Define and Punish Clause.
    
    WINTHROP, supra, at 831
    .
    29
    The government argues that it would be “anomalous”—
    and three of our colleagues call it “absurd”—to conclude that
    the war powers authorize Congress to establish military
    commissions but not vest them with jurisdiction over specific
    offenses. See Resp’t’s Br. 31; Kavanaugh Op. at 7 n.5. But as
    noted above, the Supreme Court has repeatedly drawn this
    precise distinction. Thus, even were we to determine the
    scope of the Article III exception by reference to Congress’s
    Article I powers, it would still be constrained by international
    law.
    Despite Quirin’s discussion of Congress’s Article I
    powers in determining whether the President and Congress
    had the authority to establish military commissions, Quirin
    did not look to Congress’s Article I powers in determining the
    scope of the Article III exception. See 
    Quirin, 317 U.S. at 39
    –
    41. Rather, it looked to historical practice regarding military
    commissions at the time that the Constitution was adopted to
    conclude that Article III posed no bar to military trials of
    enemy combatants who violate the laws of war. 
    Id. The government
    next argues that Congress may define
    conspiracy to commit war crimes as a law-of-war offense by
    virtue of its power to define and punish offenses against the
    “Law of Nations.” See Resp’t’s Br. 55; see also Millett Op. at
    38–39. In support, it claims that international law includes
    sufficiently analogous notions of criminal liability. Resp’t’s
    Br. 3.
    But, as the government admits, “[w]hen conspiracy is
    used as a mode of liability under international law, there is
    generally a requirement that the object offense be completed
    or attempted.” Resp’t’s Br. 56. The military commission in al
    Bahlul’s case was instructed that it could convict him of
    conspiracy without “[p]roof that the offense[s]” that were the
    30
    objects of the conspiracy—murder, attacking civilians or
    objects, murder and destruction of property in violation of the
    law of war, terrorism, and providing material support for
    terrorism—“actually occurred.” Trial Tr. 848. Neither, under
    these instructions, did al Bahlul’s overt act in furtherance of
    the conspiracy have to be a criminal act; as an element of
    proof of a standalone conspiracy charge, the overt act serves
    merely as “a clear indication that the conspiracy is being
    carried out.” 
    Id. at 849.
    The government also points to prosecutions for
    conspiracy brought under the domestic laws of individual
    allied governments following World War II, see Resp’t’s Br.
    55, but those prosecutions are irrelevant to whether
    conspiracy was a punishable offense against international law.
    Many offenses that are punished by many, if not all, countries
    are not of concern to international law because “international
    law addresses only those ‘wrong[s]’ that are ‘of mutual, and
    not merely several, concern’ to States.” Flores v. Southern
    Peru Copper Corp., 
    414 F.3d 233
    , 249 (2d Cir. 2003)
    (quoting Filartiga v. Pena-Irala, 
    630 F.2d 876
    , 888 (2d Cir.
    1980)); see also United States v. Bellaizac-Hurtado, 
    700 F.3d 1245
    , 1252 (11th Cir. 2012).
    To be sure, when Congress legislates for the punishment
    of war crimes outside of Article III courts, it may have
    authority to clarify somewhat murky areas of international
    law. See U.S. CONST. art. I, § 8, cl. 10. But Congress certainly
    has no power to make up that law entirely. See, e.g., Military
    Commissions, 11 Op. Att’y Gen. 297, 299 (1865) (“To define
    is to give the limits or precise meaning of a word or thing in
    being; to make is to call into being. Congress has power to
    define, not to make, the laws of nations . . . .”) (second
    emphasis added); see also 2 THE RECORDS OF THE FEDERAL
    CONVENTION OF 1787, at 615 (Max Farrand ed., rev. ed. 1937)
    31
    (Statement of Gouverneur Morris); 
    Bellaizac-Hurtado, 700 F.3d at 1250
    (“The insertion of the power to “define” enabled
    Congress to provide notice to the people through codification;
    it did not enable Congress to create offenses that were not
    recognized by the law of nations.”); cf. United States v.
    Furlong, 18 U.S. (5 Wheat.) 184, 198 (1820) (when
    exercising its power to define and punish piracy, Congress
    cannot redefine that offense). Indeed, in clear contrast to
    Congress’s authority to “make Rules for the Government and
    Regulation of the land and naval Forces,” U.S. CONST. art. I,
    § 8, cl. 14 (emphasis added), Congress has the authority only
    to “define” offenses against the law of nations. See also NOAH
    WEBSTER, 1 A COMPENDIOUS DICTIONARY OF THE ENGLISH
    LANGUAGE 79 (1806) (“define” means “to explain, limit,
    mark out, fix, decide”); SAMUEL JOHNSON, 1 A DICTIONARY
    OF THE ENGLISH LANGUAGE, at dlvii (6th ed. 1785) (“define”
    means “to give definition, to explain a thing by its qualities
    and circumstances”; or “to circumscribe, to mark the limit, to
    bound”).
    Here, as the government asserts, Congress in the Military
    Commissions Act of 2006 has done much more than codify an
    accepted but not fully defined concept of international law; it
    has made a new war crime, one that the international
    community has repeatedly declined to adopt. See Part 
    II.B, supra
    . Whether Congress might be entitled to the type of
    leeway the government suggests when it exercises its define
    and punish powers to legislate for the punishment of crimes in
    Article III courts, it did no such thing in the Military
    Commissions Act. That Act legislated for the punishment of
    crimes in military commissions. In doing so, it ran up against
    a clear constitutional limit: Article III’s commitment of the
    “judicial Power” to the Supreme Court and “such inferior
    Courts as Congress may from time to time ordain and
    establish.” U.S. CONST. art. III, § 1.
    32
    The government also invokes the Necessary and Proper
    Clause, U.S. CONST. art. I, § 8, cl. 18, which authorizes
    Congress to “make all Laws which shall be necessary and
    proper for carrying into Execution the foregoing Powers.”
    The government argues that Congress may enact legislation
    necessary to comply with the nation’s “international
    responsibilities,” and that Congress was reasonably seeking to
    fulfill its obligation to prevent acts of terrorism and war
    crimes when it made conspiracy punishable by military
    commission. Resp’t’s Br. 58. It points to the nation’s
    responsibilities under the Geneva Convention Relative to the
    Protection of Civilian Persons in Time of 
    War, supra
    , 6
    U.S.T. 3516, 75 U.N.T.S. 287, which prohibits “[c]ollective
    penalties and likewise all measures of intimidation or of
    terrorism.” 
    Id. art. 33.
    The Convention requires signatories to
    “undertake to enact any legislation necessary to provide
    effective penal sanctions for persons committing, or ordering
    to be committed, any of the grave breaches of the present
    Convention,” 
    id. art. 146,
    which include the “willful killing
    . . . of a protected person,” 
    id. art. 147,
    defined as “those who
    . . . find themselves, in case of a conflict or occupation, in the
    hands of a Party to the conflict or Occupying Power of which
    they are not nationals,” 
    id. art. 4.
    But the Necessary and Proper Clause does not allow
    Congress to do what it is otherwise expressly barred from
    doing. See United States ex rel. Toth v. Quarles, 
    350 U.S. 11
    ,
    21–22 (1955). And however it may affect Congress’s define
    and punish power when it legislates for the punishment of
    international offenses in Article III courts, the Necessary and
    Proper Clause cannot be read to allow Congress to do an end
    run around the constitutional limit imposed by Article III. See
    
    id. at 22;
    Reid, 354 U.S. at 22 
    (plurality opinion); see also
    Northern 
    Pipeline, 458 U.S. at 73
    (plurality opinion)
    33
    (“[W]here Art. III does apply, all of the legislative powers
    specified in Art. I and elsewhere are subject to it.”).
    Article III’s limitations on congressional power apply
    even where Congress exercises its powers to enact
    “legislation necessary to carry out its international obligation
    to prevent terrorism as a mode of warfare.” Resp’t’s Br. 57.
    The political branches’ efforts to comply with international
    obligations must also comply with the Constitution. See
    Medellin v. Texas, 
    552 U.S. 491
    , 520 (2008); 
    Reid, 354 U.S. at 16
    (plurality opinion). Even assuming that Congress could
    only meet its international obligations by criminalizing
    conduct not recognized as an offense against international
    law, the government never explains why its asserted authority
    to do so under Article I would imply the power to establish
    military jurisdiction over that conduct. See United States v.
    Arjona, 
    120 U.S. 479
    , 484 (1887).
    Ultimately, whether Congress’s authority to codify the
    offenses triable by military commissions is grounded in its
    define and punish powers or its war powers is beside the
    point. So too is the Necessary and Proper Clause’s impact on
    Congress’s Article I authority to comply with its international
    obligations by going somewhat beyond the current scope of
    international law. Whichever clause in Article I, § 8 grants
    Congress the authority to establish and determine the offenses
    triable by military commissions, and whatever the impact of
    the Necessary and Proper Clause on Congress’s Article I
    powers, Congress may not transgress the bounds of Article
    III. Article III does include an exception for law-of-war
    military commissions. But that has been narrowly defined by
    reference to the international laws and customs governing
    war. 
    Quirin, 317 U.S. at 38
    –41.
    34
    D.
    The government last falls back on the idea that
    Article III’s scope must be determined by reference to
    historical practice. This argument comes in two forms. First,
    the government maintains that spying and aiding the enemy
    are not violations of the international laws of war but that
    Congress has made those offenses triable by military
    commission since the early days of the Republic. This, its
    argument continues, shows that early congresses believed
    Article III poses no bar to making domestic crimes punishable
    by military commission. Second, the government maintains
    that “the experience of our wars and the acts and orders of our
    wartime tribunals reflect a long history of trying conspiracy to
    violate the laws of war in a military commission,” Resp’t’s
    Br. 2–3; see Kavanaugh Op. at 14–19, 21, and that Article III
    must be considered in light of that practice. Neither argument
    advances the government’s cause.
    With respect to the first, it is true that Congress has long
    made spying and aiding the enemy punishable by military
    commission. See, e.g., An Act for Establishing Rules and
    Articles for the Government of the Armies of the United
    States, § 2, 2 Stat. 359, 371 (1806) (Articles of War). But the
    government’s reliance on early congressional statutes making
    spying and aiding the enemy punishable by military
    commission suffers from two flaws. First, the government
    cites nothing indicating early congresses actually knew that
    those two offenses did not violate the international laws of
    war, and some sources suggest they might well have believed
    that those offenses did. For instance, an 1806 statute
    “imposed the death penalty on alien spies ‘according to the
    law and usage of nations, by sentence of a general court
    martial.’” 
    Quirin, 317 U.S. at 41
    (quoting Act of Congress of
    Apr. 10, 1806, 2 Stat. 359, 371). A 1776 Resolution adopted
    35
    by the Continental Congress contained a nearly identical
    provision. See Resolution of Aug. 21, 1776, 5 JOURNALS OF
    THE CONTINENTAL CONGRESS 693 (Ford ed. 1906). In 1865,
    the Attorney General of the United States, James Speed, also
    concluded in a formal opinion that “every lawyer knows that a
    spy was a well-known offender under the laws of war, and
    that under and according to those laws he could have been
    tried and punished without an act of Congress.” 11 Op. Att’y
    Gen. at 312, 313. Thus, we cannot infer from those early
    statutes that early congresses understood Article III to pose no
    bar to the punishment of domestic war crimes in military
    tribunals.
    But even were there evidence that early congresses
    understood that spying and aiding the enemy were not
    international law-of-war offenses, it would shed little light on
    whether early congresses felt free to punish purely domestic
    offenses as they saw fit. Both spying and aiding the enemy
    have been subject to military jurisdiction since the ratification
    of the Constitution. See 
    Quirin, 317 U.S. at 41
    ; Resolution of
    Aug. 21, 1776, 5 JOURNALS OF THE CONTINENTAL CONGRESS
    693 (Ford ed. 1906) (“[A]ll persons, not members of, nor
    owing allegiance to, any of the United States of
    America . . . who shall be found lurking as spies . . . shall
    suffer death, according to the law and usage of nations, by
    sentence of a court martial . . . .”); Resolution of Sept. 20,
    1776, 5 JOURNALS OF THE CONTINENTAL CONGRESS 799 (Ford
    ed. 1906) (“Whosoever shall relieve the enemy with money,
    victuals, or ammunition, or shall knowingly harbour or protect
    an enemy, shall suffer death, or such other punishment as by a
    court-martial shall be inflicted.”); Act of Apr. 10, 1806, 2
    Stat. 371. As a result, those two offenses may well fit within
    an established historical exception.
    36
    Indeed, although the government and four of our
    colleagues contend that Congress’s longstanding practice of
    making spying and aiding the enemy triable by military
    tribunal “strongly supports the conclusion that international
    law is not a constitutional constraint on Congress’s authority
    to make particular crimes triable by military commission,”
    Kavanaugh Op. at 12; see Resp’t’s Br. 32–33; Henderson Op.
    at 1, incorporating by reference Al Bahlul 
    II, 792 F.3d at 69
    (Henderson, J., dissenting), it seems that, if anything,
    Congress’s consistent decision to codify those two offenses—
    and those two offenses alone—undermines that conclusion.
    Had Congress, over the last two hundred years, actually
    believed itself free to punish by military tribunal whatever
    wartime conduct it deemed necessary, it would be rather
    surprising that it codified only two offenses, both of which
    were subject to military trial at the time the Constitution was
    adopted. Thus, while these two offenses may fall within an
    Article III exception based on longstanding historical practice,
    we find them uninformative regarding Congress’s general
    authority to make purely domestic crimes punishable by
    military commission.
    This brings us to the government’s final contention that
    conspiracy has long been tried by military commission in the
    United States and that it must therefore fall within a historical
    exception to Article III. Here, too, it falters.
    Importantly, when the Supreme Court has relied on
    historical practice to determine where one branch’s powers
    end and another’s begin, it has required robust evidence of a
    historical practice. For instance, in Myers v. United States,
    
    272 U.S. 52
    , 175 (1926), in examining the President’s
    removal power, the Court found more than seven decades in
    which Presidents had a continuous practice of removing
    executive branch officers without congressional involvement,
    37
    and on that basis held Congress lacked authority to restrict the
    President’s removal power. In United States v. Curtiss-Wright
    Export Corp., 
    299 U.S. 304
    , 322 (1936), the Court pointed to
    an “unbroken legislative practice which has prevailed almost
    from the inception of the national government to the present
    day” to reject a constitutional nondelegation challenge to a
    joint resolution of Congress authorizing the President to
    determine whether to embargo the sale of arms and munitions
    to belligerents in a foreign war. Recently, in National Labor
    Relations Board v. Noel Canning, 
    134 S. Ct. 2550
    (2014), the
    Court invoked a lengthy and dense historical practice defining
    the scope of the President’s authority under the Recess
    Appointments Clause, U.S. CONST. art. II, § 2, cl. 3. Upon
    identifying “thousands of intra-session recess appointments”
    and noting that “Presidents since Madison have made many
    recess appointments filling vacancies that initially occurred
    prior to a recess,” 
    id. at 2562,
    2571, the Court concluded that
    the Clause authorized such appointments. By contrast, where
    the Court found only a handful of instances in which a
    President had made a recess appointment during an inter-
    session recess lasting less than ten days, the Court held that
    those recesses were “presumptively too short to fall within the
    Clause.” 
    Id. at 2567.
    There is no such robust history of trying inchoate
    conspiracy before law-of-war military commissions. See
    
    Hamdan, 548 U.S. at 604
    (plurality opinion). The government
    has identified only a handful of at best ambiguous examples,
    see Resp’t’s Br. 40–43, and none in which a conviction was
    for inchoate conspiracy by a law-of-war commission that was
    affirmed by the Judicial Branch. The examples are
    unpersuasive in themselves and insufficient to establish a
    longstanding historical practice that would justify a more
    expansive understanding of the law-of-war military
    commission exception to Article III.
    38
    First, the government places substantial reliance on Civil
    War era historical practice, but that practice does not support
    its case. For instance, although the charges against the
    Lincoln assassins referred to conspiracy, the specifications
    listed the elements of the completed offense—“traitorously”
    murdering President Lincoln. See J. Holt & T. Ewing,
    CHARGE AND SPECIFICATION AGAINST DAVID E. HEROLD, ET
    AL. 3 (1865); see also 
    Hamdan, 548 U.S. at 604
    n.35
    (plurality opinion); 
    id. at 609;
    General Court-Martial Orders
    No. 356, War Dep’t (July 5, 1865), reprinted in H.R. Doc.
    No. 55-314, at 696 (1899). The Attorney General’s formal
    opinion in 1865 also described the charge as “the offence of
    having assassinated the President.” 11 Op. Att’y Gen. at 297;
    see 
    id. at 316–17.
    As such, it appears that conspiracy was at
    most a theory of liability on which to hold each of the
    partners to account for the assassination completed by Booth
    alone.
    Construing the Lincoln assassins’ case as a conspiracy
    conviction is anachronistic and conflates conspiracy as a
    theory of liability with inchoate conspiracy as a standalone
    offense. See Kavanaugh Op. at 15–16. Prosecution of
    conspiracy as a standalone offense, chargeable apart from and
    in addition to the crimes that are the conspiracy’s object and
    carrying their same penalties, is a modern innovation. See
    Iannelli v. United States, 
    420 U.S. 770
    , 781 & n.13 (1975)
    (citing Hampton L. Carson, The Law of Criminal
    Conspiracies and Agreements as Found in the American
    Cases, in R. WRIGHT, THE LAW OF CRIMINAL CONSPIRACIES
    AND AGREEMENTS 191 (1887)). At the time of the Lincoln
    assassination, it was unclear that conspiracy could even be
    charged separately from its object offense, once completed.
    See 
    id. And when
    Congress first codified conspiracy as a
    crime in 1867, it carried only a two-year penalty. See Act of
    
    39 A.K. Marsh. 2
    , 1867, 14 Stat. 471, 484. Conspiracy as then
    understood would hardly have been an appropriate principal
    charge against the President’s assassins. The government
    mistakenly reads our modern understanding of conspiracy
    into events, including the Lincoln assassins’ conviction, from
    an era in which that understanding had not yet taken hold, a
    move that fundamentally miscasts that earlier precedent.
    Further, Winthrop noted that the Lincoln assassins’
    tribunal was a mixed martial-law and law-of-war military
    commission. See WINTHROP, MILITARY 
    LAW, supra, at 839
    &
    n.5; cf. 
    id. at 842.
    The unreported district court opinion in Ex
    parte Mudd, 
    17 F. Cas. 954
    (1868), see Kavanaugh Op. at
    15–16, does not undermine that conclusion; the district court
    described the offense as “assassination” of the Commander in
    Chief and only used “conspiracy” in the same terms as the
    charging document, while distinguishing Ex parte Milligan
    based on the state of war in the Capital, not based on the
    nature of the offense. Ex parte 
    Mudd, 17 F. Cas. at 954
    . Thus,
    “even if [it could be] properly classified as a trial by law-of-
    war commission, [the Lincoln assassins’ trial] is at best an
    equivocal exception.” 
    Hamdan, 548 U.S. at 604
    n.35
    (plurality opinion) (internal citation omitted); see also Al
    Bahlul 
    II, 792 F.3d at 12
    .
    Second, the government asserts that other Civil War
    precedents show that defendants were charged with
    conspiracies as unconsummated offenses. Resp’t’s Br. 42–43.
    The examples on which it relies do not support its position.
    Col. George St. Leger Grenfel was convicted by a military
    tribunal of conspiracy to free prisoners of war in Chicago and
    to destroy that city. See GENERAL COURT MARTIAL ORDERS
    No. 452, War Dep’t (Aug. 22, 1865), reprinted in H.R. Doc.
    No. 55-314, at 724–35. As al Bahlul points out, Grenfel’s
    commission, like that of the Lincoln assassins, was a
    40
    “hybrid” commission exercising jurisdiction based in part on
    the President’s declaration of martial law. See Reply Br. 20
    (citing 
    Hamdan, 548 U.S. at 609
    n.37 (plurality opinion);
    WINTHROP, MILITARY 
    LAW, supra, at 839
    n.5); S. STARR,
    COLONEL GRENFEL’S WARS: THE LIFE OF A SOLDIER OF
    FORTUNE, 5, 219 (1971) (cited in Resp’t’s Br. 41). Such
    hybrid commissions “regularly tried war crimes and ordinary
    crimes together,” 
    Hamdan, 548 U.S. at 608
    , and the crimes
    charged were, “‘[n]ot unfrequently[,] . . . a combination of
    the two species of offenses’”—that is, hybrid versions of law-
    of-war offenses and domestic crimes, 
    id. (quoting C.
    HOWLAND, A DIGEST OF OPINIONS OF THE JUDGE ADVOCATES
    GENERAL OF THE ARMY 1071 (1912)). These cases thus
    provide little insight into the traditional jurisdiction of pure
    law-of-war military commissions. Indeed, in defending the
    jurisdiction of the Grenfel commission, the prosecution relied
    on the fact that “martial law obtained throughout the United
    States and the Territories during the continuance of the
    [Civil] [W]ar.” Judge Advocate’s Reply, Courtroom,
    Cincinnati, Ohio, Jan. 17, 1865, United States v. Walsh, et al.,
    reprinted in H. EXEC. DOC. NO. 50, 39th Cong., 2d Sess., at
    20. The Grenfel commission, like the Lincoln assassins’
    commission, “is at best an equivocal” example. 
    Hamdan, 548 U.S. at 604
    n.35 (plurality opinion).
    The government’s reliance on the case of Confederate
    Army Captain Henry Wirz is similarly misplaced; in his case
    conspiracy served only as a mode of liability for the
    completed law-of-war offenses of abusing, torturing, and
    murdering war prisoners. GENERAL COURT MARTIAL
    ORDERS, No. 607, War Dep’t (Nov. 6, 1865), reprinted in
    H.R. Doc. No. 55-314, at 785, 789.
    Also unavailing are the government’s citations to
    William Winthrop’s 1880 Digest of Opinions of the Judge
    41
    Advocate General of the Army and to Charles Roscoe
    Howland’s 1912 Digest of Opinions of the Judge Advocate
    General of the Army. Both stated that, during the Civil War,
    one of the principal offenses charged in military commissions
    as an offense against the laws of war was “[c]onspiracy by
    two or more to violate the laws of war by destroying life or
    property in aid of the enemy.” W. WINTHROP, A DIGEST OF
    OPINIONS OF THE JUDGE ADVOCATE GENERAL OF THE ARMY
    329 (1880); 
    HOWLAND, supra, at 1071
    . But a Supreme Court
    plurality has already examined the cases cited and concluded
    that they provide “no support for the inclusion of conspiracy
    as a violation of the law of war.” 
    Hamdan, 548 U.S. at 607
    (plurality opinion). And, as that plurality further noted,
    Winthrop’s subsequent treatise, Military Law and Precedents,
    does not list conspiracy as an offense against the laws of war.
    
    Id. at 608
    (citing WINTHROP, MILITARY 
    LAW, supra, at 839
    –
    40).
    Indeed, in his later treatise, Winthrop clarified the issue.
    In describing the mixed jurisdiction of military commissions
    during the Civil War, he noted that the tribunals presided over
    two classes of offenses—“(1) Crimes and statutory offenses
    cognizable by State or U.S. courts, and which would properly
    be tried by such courts if open and acting; [and] (2) Violations
    of the laws and usages of war cognizable by military tribunals
    only.” WINTHROP, MILITARY 
    LAW, supra, at 839
    . He
    identified criminal conspiracy as a crime of the first class, but
    made no mention of conspiracy in the second. In a footnote,
    he also identified many of the conspiracy cases to which the
    government now points, including those of Wirz, Grenfel, and
    the Lincoln assassins, as having been of the first class (i.e.,
    cases charging crimes normally triable only in civil court) or
    “of the first and second classes combined,” 
    id. at 839
    n.5, that
    is, cases charging “species of compound offense[s] of the type
    tried by the hybrid military commissions of the Civil War,”
    42
    
    Hamdan, 548 U.S. at 608
    (plurality opinion). Those cases
    thus fail to support the government’s contention that there is a
    robust history of trying conspiracy in pure law-of-war military
    commissions.
    Third, the government draws on World War II-era
    practice. Although the charges against the Nazi saboteurs in
    Quirin included conspiracy, the Supreme Court upheld the
    jurisdiction of the law-of-war military commission only as to
    the charge of passing behind enemy lines with hostile
    purpose and did not mention conspiracy in its analysis. See
    
    Quirin, 317 U.S. at 46
    . Similarly, although William
    Colepaugh was convicted of sabotage and spying, in addition
    to conspiracy to commit those offenses, the U.S. Court of
    Appeals for the Tenth Circuit affirmed the jurisdiction of the
    military tribunal in view of the law-of-war offense of
    unlawful belligerency only, without addressing the
    conspiracy charge. See Colepaugh v. Looney, 
    235 F.2d 429
    ,
    431–32 (10th Cir. 1956).
    The government insists that these cases are nonetheless
    important because “despite such judicial review, ‘no U.S.
    court has ever cast any doubt on the landmark military
    commission convictions embracing conspiracy charges, or the
    validity of trying conspiracy by military commission.’”
    Resp’t’s Br. 37–38 (quoting Al Bahlul 
    I, 767 F.3d at 70
    (Kavanaugh, J., concurring in the judgment in part and
    dissenting in part)) (alterations omitted). To this, it adds that
    executive branch officials, including the President, approved
    the charges in both cases, thereby giving their “imprimatur” to
    the convictions. 
    Id. at 38.
    But at most those cases underscore the uncertain position
    that the crime of conspiracy has occupied in the history of
    military commissions. The defendants in both Quirin and
    43
    Colepaugh challenged the conspiracy charges on the ground
    that the military commissions lacked jurisdiction over that
    offense, see Brief for Petitioner at 29, Quirin, 
    317 U.S. 1
    ;
    Opinion of Special Board of Review, United States v.
    Colepaugh, CM 276026, at 28 (Mar. 27, 1945), suggesting
    that it was in no sense well established that military tribunals
    had jurisdiction to preside over conspiracy charges.
    Additionally, the court in each case focused on completed
    violations of the international laws of war and declined to
    address the legitimacy of the conspiracy charges, indicating
    that those charges may have presented difficult questions. In
    Hamdan, four Justices recognized as much, stating:
    If anything, Quirin supports Hamdan’s argument that
    conspiracy is not a violation of the law of war. Not
    only did the Court pointedly omit any discussion of
    the conspiracy charge, but its analysis of Charge I
    placed special emphasis on the completion of an
    offense; it took seriously the saboteurs’ argument that
    there can be no violation of the law of war—at least
    not one triable by military commission—without the
    actual commission of or attempt to commit a hostile
    and warlike 
    act. 548 U.S. at 606
    –07 (plurality opinion) (internal quotation
    marks omitted)). Thus, these cases appear neutral at best and,
    more likely, undermine the government’s position.
    The government also relies on evidence that the
    executive branch has viewed conspiracy as triable by military
    commission, suggesting that this is entitled to some weight.
    Resp’t’s Br. at 34–46; see Kavanaugh Op. at 14–18. But the
    executive branch opinions on which it relies rest on shaky
    foundations. For example, although Assistant Attorney
    General Tom Clark concluded in a memorandum that
    44
    William C. Colepaugh could be tried for conspiracy in a law-
    of-war military commission, the sources on which he relied
    drew almost exclusively from martial-law commissions that
    exercised plenary jurisdiction, not law-of-war military
    commissions of the kind at issue here. See Memorandum
    from Tom C. Clark, Assistant Attorney General, to Myron C.
    Kramer, Judge Advocate General (Mar. 12, 1945), reprinted
    in Government Supplemental Appendix 104–10 (citing, inter
    alia, the Lincoln Assassins and Captain Wirz).
    The orders of General MacArthur from the Korean
    Conflict, see Resp’t’s Br. 39; Millet Op. at 41, also offer
    little, if any, support for the government because the en banc
    court has viewed such military orders as unpersuasive for
    lack of high-level Executive Branch consultation. See Al
    Bahlul 
    I, 767 F.3d at 25
    n.16. And during the Korean Conflict
    there apparently were no prosecutions conducted by United
    Nations Military Commissions. See JORDAN J. PAUST ET AL.,
    INTERNATIONAL CRIMINAL LAW: CASES AND MATERIALS 724
    (1996).
    In sum, the Supreme Court has recognized a limited
    Article III exception for the prosecution of internationally
    recognized war crimes in military tribunals. The government
    has offered no reason—rooted in history, the Constitution,
    case law, or anything else—for extending that exception
    further.
    III.
    We turn now to the additional arguments of our
    colleagues.
    45
    A.
    Four of our colleagues believe that Hamdan supports the
    notion that Congress can vest law-of-war military
    commissions with jurisdiction over inchoate conspiracy
    without transgressing the bounds of Article III because
    several Justices in Hamdan “expressly invited Congress to
    clarify the scope of military commission power” without
    “even hint[ing] at a lurking constitutional problem with trying
    conspiracy offenses before military commissions.”
    Kavanaugh Op. at 26; see also Henderson Op. at 1,
    incorporating by reference Al Bahlul 
    II, 792 F.3d at 50-52
    (Henderson, J., dissenting); Resp’t’s Br. 53.
    The Justices’ invitation to Congress in Hamdan is,
    however, a thin reed on which to rest. For one thing, it is far
    from clear that the invitation was in any way related to
    Congress’s ability to make inchoate conspiracy punishable by
    military commission. Hamdan’s principal holding was that
    the commissions convened under Military Commission Order
    No. 1, such as Salim Hamdan’s, were invalid because their
    procedures failed to comport with statutory 
    requirements. 548 U.S. at 613
    . The Justices’ may have thus intended their
    “invitation” to underscore nothing more than Congress’s
    power to authorize the invalidated procedures. See 
    id. at 636
    (Breyer, J., concurring) (“Congress has denied the President
    the legislative authority to create military commissions of the
    kind at issue here. Nothing prevents the President from
    returning to Congress to seek the authority he believes
    necessary.”).
    Perhaps equally important, the issues presented in
    Hamdan did not include the question we consider here, i.e.,
    whether Article III limits Congress’s authority to vest military
    commissions with jurisdiction over conspiracy charges. The
    46
    two questions on which the Supreme Court granted certiorari
    asked: (1) whether the President required congressional
    authorization to establish law-of-war military commissions
    and, if so, whether the President had received such
    authorization; and (2) whether Guantanamo detainees could
    enforce the provisions of the 1949 Geneva Conventions in
    habeas corpus proceedings. Although the parties’ briefs in
    Hamdan touched on related issues, neither side squarely
    addressed Article III’s limits on military-commission
    jurisdiction. This court should, accordingly, not read too
    much into the Justices’ invitation.
    Next, Judge Kavanaugh, like the government, believes
    that Congress derives its authority to determine the offenses
    triable by military commission from its war powers and that
    those powers are unconstrained by international law. In his
    view, the Constitution cannot possibly give the international
    community—through the development of international law—
    the ability to limit Congress’s exercise of its war powers.
    Kavanaugh Op. at 8–9. It is not international law, however,
    that constrains Congress’s authority here—it is Article III.
    The Framers of the Constitution expected Article III courts to
    have jurisdiction over the trial of all crimes, 
    Toth, 350 U.S. at 15
    ; 
    Reid, 354 U.S. at 21
    (plurality opinion), save for a few
    narrow exceptions, such as battlefield prosecutions of enemy
    combatants who “in their attempt to thwart or impede our
    military effort have violated the law of war,” 
    Quirin, 317 U.S. at 2
    8–29; 
    id. at 41–42.
    The international-law constraint that
    Quirin recognized and that we would apply here functions not
    as an independent constraint on the political branches’ powers
    to wage war, but rather as an essential demarcation between
    military and civilian jurisdiction. Without it, “the line between
    civilian and military jurisdiction could become elusive—if not
    altogether illusory.” National Institute of Military Justice
    Amicus Br. 29. We find apt here the Supreme Court’s
    47
    warning in Northern 
    Pipeline, 458 U.S. at 73
    –74 (plurality
    opinion), against constitutional interpretations that would
    “replace the principles delineated in [Supreme Court]
    precedents, rooted in history and the Constitution, with a rule
    of broad legislative discretion that could effectively eviscerate
    the constitutional guarantee of an independent Judicial Branch
    of the Federal Government.”
    The idea that international law has a role to play in our
    constitutional framework is also not as surprising as one
    might think. The Framers of the Constitution well understood
    that our country’s newly forged sovereignty brought with it
    both rights and obligations. John Jay, the first Chief Justice of
    the United States, explained in 1793 that the United States
    “had, by taking a place among the nations of the earth,
    become amenable to the laws of nations.” Chisholm v.
    Georgia, 2 U.S. (2 Dall.) 419, 474 (1793) (opinion of Jay,
    C.J.). Embracing the law of nations and adhering to its
    principles, he further explained, was the new nation’s “duty”
    and in its own “interest.” Id.; see also Who Privileged from
    Arrest, 1 Op. Att’y Gen. 26, 27 (1792) (The law of nations’
    “obligation commences and runs with the existence of a
    nation.”).
    There is nothing anomalous or contrary to national
    security in vesting Article III courts with exclusive power to
    try all crimes except for internationally recognized war crimes
    that have been traditionally tried by military commission. Our
    military has long abided by the international laws of war. For
    instance, in its 1940 Rules of Land War, it noted that the
    “well-established rules known as the rules or laws of war”
    that govern the conduct of war among civilized nations “are
    binding upon all civilized nations,” and are to “be strictly
    observed by our forces.” War Department, Rules of Land
    Warfare 1–2 (1940). Both the Framers’ and our military’s
    48
    desire to adhere to the law of nations and, more specifically,
    the laws of war appears sound: “If the United States now
    decides that it can hold foreign personnel accountable for
    violating ‘national’ law-of-war rules, other states will be
    entitled to assert the same authority.” Glazier Amicus Br. 27;
    see 
    Arjona, 120 U.S. at 487
    (“[W]hat is law for one is, under
    the same circumstances, law for the other.”).
    Standing firm on the constitutionally prescribed
    boundaries between civilian and military jurisdiction is
    compelled by Supreme Court precedent and doubly
    compelled where, as here, the government has made no claim
    of military necessity. Military exigency, although insufficient
    to justify military jurisdiction, is nevertheless a necessary
    condition. 
    Hamdan, 548 U.S. at 590
    . But remarkably,
    throughout this protracted litigation, the government has
    offered no reason to believe that expanding the traditionally
    understood scope of Article III’s exception for law-of-war
    military commissions is necessary to meet a military
    exigency. We claim no authority to determine military
    necessity; we simply note that the government has asserted no
    such exigency here. Perhaps the government has eschewed a
    claim of military necessity because of the many other tools at
    its disposal. Congress remains free to enact, and the President
    to employ, domestic laws to bring terrorists to justice before
    Article III courts, as they have on hundreds of occasions
    already with remarkable success. See Al Bahlul 
    II, 792 F.3d at 27
    (Tatel, J., concurring); Center on Law and Security, New
    York University School of Law, Terrorist Trial Report Card:
    September 11, 2001–September 11, 2011, at 2, 7, tbl.1,
    available at http://goo.gl/Ks3Okc (reporting that in the ten
    years after September 11, 2001, federal prosecutors had
    obtained convictions in almost 200 “jihadist-related”
    terrorism and national security cases); Press Release,
    Department of Justice, Fact Sheet: Prosecuting and Detaining
    49
    Terror Suspects in the U.S. Criminal Justice System (June 9,
    2009) (citing Richard B. Zabel & James L. Benjamin, Jr.,
    Human Rights First, In Pursuit of Justice: Prosecuting
    Terrorism Cases in the Federal Courts 23 (May 2008),
    available      at    http://www.humanrightsfirst.org/resource/
    pursuit-justice); see also, e.g., Nizar Trabelsi, No. 15-3075
    (D.C. Cir., argued May 17, 2016); United States v. Ghailani,
    
    733 F.3d 29
    (2d Cir. 2013).
    For detainees ill-suited for prosecution in Article III
    courts, the government has other options. It may detain them
    as enemy belligerents. See Hamdi v. Rumsfeld, 
    542 U.S. 507
    ,
    518–24 (2004) (plurality opinion). It may continue to try
    violations of the laws of war in military commissions. See,
    e.g., Government Response to Defense Motion to Dismiss for
    Lack of Jurisdiction, AE107A, at 1, United States v.
    Mohammad (M.C. Jan. 16, 2013) (acquiescing to Khalid
    Shaikh Mohammad’s and his codefendants’ motion to dismiss
    charges for inchoate conspiracy, but continuing to pursue
    charges of recognized law-of-war offenses, including
    attacking civilians on September 11, 2001). It might also help
    craft new international conventions to address the demands of
    new kinds of war and implement appropriate procedures for
    prisoners of war. See generally 
    Hamdan, 548 U.S. at 619
    .
    On this note, it is worth remembering that, historically,
    the military has not been in the business of prosecuting
    individuals for crimes and locking them up for life. Its
    primary mission has always been to defeat our enemies on the
    battlefield. Cf. 
    Reid, 354 U.S. at 35
    (plurality opinion) (“[T]he
    business of soldiers is to fight and prepare to fight wars, not to
    try civilians for their alleged crimes.”); 
    Toth, 350 U.S. at 17
    (“Unlike courts, it is the primary business of armies and
    navies to fight or be ready to fight wars should the occasion
    arise. . . . [T]rial of soldiers to maintain discipline is merely
    50
    incidental to an army’s primary fighting function.”). To be
    sure, punishing enemy belligerents who violate the
    international rules governing armed conflicts is an “important
    incident” to waging war. 
    Quirin, 317 U.S. at 2
    8. Such
    punishment helps encourage adherence to the laws of war.
    But restricting the military’s ability to intrude on the
    judiciary’s domain hardly raises the types of concerns that
    enforcing the limits on the President’s other war powers
    could.
    B.
    Judge Millett and Judge Wilkins take a very different
    tack. Although seeming to recognize the lack of legal support
    for prosecuting inchoate conspiracy before pure law-of-war
    military commissions, they believe that we can nonetheless
    affirm al Bahlul’s conviction because they think the facts, as
    they understand them to have been found by the military
    commission members, necessarily show that al Bahlul
    engaged in conduct for which he could have been tried and
    punished in a military commission. See Millett Op. at 2, 29–
    38; Wilkins Op. at 1, 8–14. In other words, they would
    overlook the fact that al Bahlul was charged only with
    conspiracy as a standalone crime because, as they see it,
    record evidence could have supported criminal liability under
    international law—e.g., for the murder of protected persons
    under a joint criminal enterprise theory of liability—and there
    is, therefore, no Article I or Article III problem. Millett Op. at
    29–38; Wilkins Op. at 13–14. That approach suffers from
    several flaws.
    Most critically, the government never even hinted at such
    an approach in its brief. To the contrary, at every turn, the
    government defended al Bahlul’s conviction on the ground
    that it could lawfully charge and prosecute him in a military
    51
    commission for the crime of inchoate conspiracy to violate
    the laws of war. For instance, in response to al Bahlul’s
    contention that military commissions have historically taken
    cognizance of only completed war crimes, Pet’r’s Br. 13, the
    government did not argue that the court could sustain his
    conviction on the ground that al Bahlul was essentially found
    guilty of participating in a completed war crime. It tacked in
    the opposite direction, asserting that there is historical
    precedent for trying conspiracy in cases where the object
    offenses were never completed. See Resp’t’s Br. 42–43.
    Moreover, in arguing that Congress acted consistently with
    international law, the government did not take the opportunity
    to defend al Bahlul’s conviction as resting on conduct
    virtually the same as conduct for which he could have been
    punished under international law. See 
    id. Instead, it
    acknowledged that the crime for which al Bahlul was charged
    and convicted differed from any recognized international law
    concept of criminal liability, because to support a war crime
    conviction on a joint criminal enterprise theory of liability
    international law generally “require[s] that the object offense
    be completed or attempted,” 
    id. at 56,
    and the government
    stressed that the MCA’s “requirement that the defendant
    personally commit an overt act is not the same as the
    requirement that the object crime be completed,” 
    id. It is
    by now well established that this court ordinarily
    declines to decide cases based on arguments not raised by
    either party. As we have explained on numerous occasions,
    “[t]he premise of our adversarial system is that appellate
    courts do not sit as self-directed boards of legal inquiry and
    research.” Carducci v. Regan, 
    714 F.2d 171
    , 177 (D.C. Cir.
    1983). Rather, we sit as “arbiters of legal questions presented
    and argued by the parties before [us].” Id.; see United Parcel
    Service, Inc. v. Mitchell, 
    451 U.S. 56
    , 60 n.2 (1981) (“We
    decline to consider this argument since it was not raised by
    52
    either of the parties here or below.”); FED. R. APP. P.
    28(a)(8)(A), (B) (requiring parties to set forth their legal and
    factual contentions, “the reasons for them,” and “citations to
    the authorities and parts of the record” on which they rely).
    The reason for restraint is obvious: “Rulings on issues that
    have not been fully argued run the risk of being improvident
    or ill-advised.” United States v. West, 
    392 F.3d 450
    , 459
    (D.C. Cir. 2004) (internal quotation marks omitted); cf.
    
    Hamdan, 548 U.S. at 601
    n.32 (plurality opinion) (criticizing
    Justice Thomas’s focus on crimes not charged and noting that
    “the Government plainly had available to it the tools and the
    time it needed to charge petitioner with the various crimes
    [Justice Thomas] refer[red] to, if it believed they were
    supported by the allegations.”). Here, venturing down the path
    proposed by Judge Millett and Judge Wilkins without the aid
    of the parties runs the risk of misinterpreting record evidence
    and failing to anticipate legal objections that the parties might
    have to this approach.
    We put those concerns aside only to explain why we
    believe that Judge Millett’s and Judge Wilkins’s analysis is
    incorrect. First, we fail to see how their emphasis on facial
    versus as-applied challenges makes a difference with respect
    to al Bahlul’s Article III claim. The Article III inquiry focuses
    on the nature of the offense charged. It is true that courts
    generally should not concern themselves with the application
    of statutes beyond the facts of the cases before them, but al
    Bahlul never asks us to do so. The circumstances of his
    prosecution make plain that his conviction runs afoul of
    Article III because he was charged and prosecuted in a
    military commission for a crime that is not triable before such
    a tribunal. Thus, in seeking to overturn his conviction, al
    Bahlul does not ask the court to consider the rights of
    hypothetical defendants or to consider whether the MCA
    might impermissibly authorize trial by military commission
    53
    for offenses other than what was charged here. He asks this
    court to consider only the circumstances of his own
    prosecution and conviction. And, for the reasons stated in Part
    
    II, supra
    , his prosecution and resulting conviction in a
    military commission for inchoate conspiracy was invalid.
    Attempting to avoid this conclusion, our colleagues
    suggest an “as-applied” approach under which the court
    would look past the charges against al Bahlul and uphold his
    conviction so long as the military commission members’
    findings could have supported criminal liability for a law-of-
    war offense. See Millett Op. at 2, 29–38; Wilkins Op. at 1-5,
    8–14. That, we think, not only asks the wrong question, but
    would raise other serious problems with al Bahlul’s
    conviction. Most critically, it would violate basic principles of
    criminal justice, including that an accused know the charge
    against him and that a conviction match the charge.
    Importantly, al Bahlul was neither charged with nor convicted
    of substantive war crimes, such as the murder of protected
    persons, on a joint criminal enterprise or conspiracy theory of
    liability. Instead, as seven members of this court recognize, al
    Bahlul was charged with, tried for, and convicted of the
    standalone crime of conspiracy. See Kavanaugh Op. at 1;
    Henderson Op. at 1, incorporating by reference Al Bahlul 
    II, 792 F.3d at 47
    (Henderson, J., dissenting).
    In the United States, conspiracy is both a crime and a
    theory of liability. Although the two concepts share the same
    name, they are quite distinct. The crime of conspiracy makes
    it unlawful for two or more persons to agree to commit a
    crime. See, e.g., 
    Iannelli, 420 U.S. at 777
    ; Smith v. United
    States, 
    133 S. Ct. 714
    , 719 (2013); Model Penal Code
    § 5.03(1). The crime of conspiracy is therefore complete as
    soon as two or more conspirators enter into an agreement to
    commit an unlawful act (and, depending on the jurisdiction,
    54
    as soon as one of the conspirators commits an overt act in
    furtherance of the conspiracy’s objectives). It matters not at
    all whether the conspiracy ever achieves its intended purpose.
    By contrast, conspiracy as a theory of liability is a
    mechanism for holding individuals responsible for crimes
    committed pursuant to a conspiratorial agreement. For
    instance, if A and B agree to murder someone and A shoots
    the gun while B acts as a lookout, B can be held just as
    responsible for the murder as A. Under the Pinkerton
    doctrine, an individual who joins a conspiracy can be held
    responsible for completed crimes he or she agreed to as part
    of the conspiracy and for any other crimes committed in
    furtherance of the conspiracy that were its reasonably
    foreseeable result. See Pinkerton v. United States, 
    328 U.S. 640
    , 646–47 (1946). Critically, when conspiracy serves as a
    mode of liability, the defendant is charged with, tried for, and
    convicted of substantive crimes, such as murder, bank
    robbery, or wire fraud, that were committed in the course of a
    conspiracy. That is, the indictment or charge sheet against the
    defendant will list murder, bank robbery, or wire fraud as the
    criminal offense for which the defendant is being tried, and
    the final judgment of conviction will identify murder, bank
    robbery, or wire fraud as the crime committed; conspiracy
    simply acts as the theory on which the defendant is held
    accountable for those crimes.
    As explained previously, international law has repeatedly
    rejected conspiracy to commit war crimes as a standalone
    offense. See Part 
    II.B, supra
    . It does, however, embrace a
    species of conspiracy liability known as joint criminal
    enterprise. 
    Hamdan, 548 U.S. at 611
    n.40 (plurality opinion);
    see Milutinović, Decision on Dragoljub Ojdanić’s Motion
    Challenging Jurisdiction—Joint Criminal Enterprise, ¶ 26.
    Under one formulation of joint criminal enterprise liability,
    55
    akin to Pinkerton liability, an individual can be held
    responsible for the criminal acts of other members of an
    enterprise so long as those acts were a “natural and
    foreseeable consequence of the . . . [enterprise’s] common
    purpose.” Prosecutor v. Tadíc, Case No. IT-94-1-A,
    Judgement, ¶ 204 (Int’l Crim. Trib. for the Former
    Yugoslavia, Appeals Chamber, July 15, 1999).
    As mentioned above, Judge Millett and Judge Wilkins
    would ignore the government’s prosecutorial choice to charge
    al Bahlul with, and convict him of, the crime of conspiracy,
    see Charge Sheet, AE01, United States v. al Bahlul (M.C.
    Feb. 26, 2008); see 10 U.S.C. § 950v(b)(28) (2006), and
    would instead uphold his conviction on the ground that he
    could have been punished in a military commission for other
    international law-of-war offenses—like the murder of
    protected persons on September 11, 2001—based on a joint
    criminal enterprise or Pinkerton theory of liability, see Millett
    Op. at 29–38; Wilkins Op. at 8–14. Meanwhile, our other
    colleagues simply do not address the distinction between the
    standalone crime of inchoate conspiracy of which al Bahlul
    was convicted, and conspiracy as a theory of liability for
    proven war crimes. See, e.g., Kavanaugh Op. at 15-19.
    The basic point here is an important one: the government
    chose not to pursue charges against al Bahlul for the murder
    of protected persons, attacking civilians, or any other
    recognized war crime for which he could have been tried
    under the 2006 MCA. See Charge 
    Sheet, supra
    ; see also Trial
    Tr. 109–113; Oral Arg. Tr. 46–47 (Dec. 1, 2015)
    (acknowledging that the government did not pursue a joint
    criminal enterprise theory of liability for substantive war
    crimes). Nor did the commission convict al Bahlul of
    murdering protected persons, attacking civilians, or
    committing any other substantive law-of-war offense. See
    56
    Findings Worksheet, AE074, United States v. al Bahlul (M.C.
    Oct. 31, 2008). In fact, the military judge expressly instructed
    commission members that in order to convict al Bahlul on
    Charge I, the conspiracy charge, they did not need to find that
    any of the alleged objects of the conspiracy—such as the
    murder of protected persons—actually occurred. See Trial Tr.
    848. They had to find only: (1) that al Bahlul entered into an
    agreement with Osama bin Laden and others to commit an
    offense triable by military commission; (2) that al Bahlul
    knew the purpose of the agreement and joined it willingly and
    with the intent to further that purpose; and (3) that al Bahlul
    committed one of several overt acts in furtherance of the
    agreement, none of which had to be criminal, much less an
    international law-of-war offense. See 
    id. 846, 849.
    If two of our colleagues believe that the military
    commission members actually found al Bahlul guilty of
    substantive offenses based on a conspiracy theory of liability
    because they indicated on their Findings Worksheet that al
    Bahlul was “guilty” of each object offense, including murder
    of protected persons, see Millett Op. at 2, 31; see also
    Findings Worksheet at 2, they are mistaken. Although that
    section of the worksheet somewhat confusingly begins
    “Guilty of Some, but Not All Objects of the Conspiracy” and
    then gives the members a place to circle “guilty” or “not
    guilty” next to each of the alleged objects of the conspiracy, it
    is clear that by circling “guilty” next to each substantive
    offense, the members were indicating only that al Bahlul had
    joined a conspiracy that had as its object each of the listed
    offenses. The charge was identified as “conspiracy,” Findings
    Worksheet at 2, and the military commission judge expressly
    instructed the members that “[i]n the specification of Charge
    I, the accused is charged with the offense of conspiracy,” Trial
    Tr. 845 (emphasis added). The judge never so much as hinted
    that Charge I also encompassed substantive offenses on a
    57
    conspiracy theory of liability. See 
    id. When one
    looks at the
    Findings Worksheet as a whole, it is also clear that the
    sections permitting the members to find al Bahlul “guilty” or
    “not guilty” of specific objects of the conspiracy and specific
    overt acts merely provided the members the opportunity to
    find, with respect to the specification for Charge I, that the
    conspiracy had some but not all of the alleged offenses as its
    objects or that al Bahlul had committed some but not all of the
    alleged overt acts. Tellingly, too, the government has never
    argued that the Findings Worksheet shows that the
    commission members actually found al Bahlul guilty of
    substantive offenses.
    There is simply no basis for upholding a conviction for
    the crime of inchoate conspiracy on the ground that a
    defendant could have been charged with and convicted of
    some other crime. To do so would violate the most
    fundamental tenets of our criminal justice system—that a
    defendant is entitled to notice of the charges against him and
    that a conviction match the charge or be a lesser included
    offense. As the Supreme Court has explained, due process
    demands that a defendant have “notice of the specific charge,
    and a chance to be heard in a trial of the issues raised by that
    charge.” Cole v. Arkansas, 
    333 U.S. 196
    , 201 (1948). “It is as
    much a violation of due process to send an accused to prison
    following conviction of a charge on which he was never tried
    as it would be to convict him upon a charge that was never
    made.” 
    Id. The Court
    has thus squarely rejected the notion
    that an appellate court can sustain a conviction under a
    provision never charged, explaining that “[t]o conform to due
    process of law, [defendants] [a]re entitled to have the validity
    of their convictions appraised on consideration of the case as
    it was tried and as the issues were determined in the trial
    court.” 
    Id. at 202.
    We sincerely doubt that these most basic
    principles of due process—well established under both
    58
    American and international law—can be cast aside in the
    military commission context. See id.; see also, e.g., Geneva
    Convention Relative to the Treatment of Prisoners of 
    War, supra
    , art. 105, 6 U.S.T. at 3396, 75 U.N.T.S. at 214
    (“Particulars of the charge or charges on which the prisoner of
    war is to be arraigned, as well as the documents which are
    generally communicated to the accused by virtue of the laws
    in force in the armed forces of the Detaining Power, shall be
    communicated to the accused prisoner of war in a language
    which he understands, and in good time before the opening of
    the trial.”); ICTY Statute, supra, arts. 18, 20–21; ICTR
    Statute, supra, arts. 17, 19–20; cf. Rome Statute, art. 22, § 
    2, supra
    ; United States v. Longmire, 
    39 M.J. 536
    , 538
    (A.C.M.R. 1994) (recognizing in the court-martial context
    that a “basic principle of due process” is that “an individual
    should not be made to face criminal charges without having
    been notified of what he must defend against and without
    having been protected against double jeopardy”).
    But we have no need to rely on constitutional or
    international-law principles to question the validity of an
    affirmance on grounds other than those charged and tried, as
    both the Military Commissions Act of 2006 and the rules
    promulgated thereunder incorporate these same notice
    principles. The Act “establish[es] a two-step process for
    initiating a trial before a military commission,” Obaydullah v.
    Obama, 
    609 F.3d 444
    , 445–46 (D.C. Cir. 2010), pursuant to
    which an authorized person subject to the Uniform Code of
    Military Justice must swear a charge, under oath, against a
    defendant, 10 U.S.C. § 948q(a); see Manual for Military
    Commissions, Rule for Military Commissions (R.M.C.) 307,
    at II-15 (2007). The Act further requires that, once charges are
    sworn against an accused, he be promptly informed of them.
    10 U.S.C. § 948q(b); see R.M.C. 308. The Act also specifies,
    in language similar to that used in the Geneva Conventions,
    59
    see Geneva Convention Relative to the Treatment of Prisoners
    of 
    War, supra
    , art. 105, 6 U.S.T. at 3396, 75 U.N.T.S. at 214,
    that the government must serve the accused with “a copy of
    the charges upon which trial is to be had in English and, if
    appropriate, in another language that the accused understands,
    sufficiently in advance of trial to prepare a defense,” 10
    U.S.C. § 948s. With minor exceptions not relevant here, any
    fact that increases the maximum punishment authorized must
    be alleged in the charge’s specification, R.M.C. 307(c)(3),
    and substantive changes to the charges cannot be made
    without newly referring charges and notifying the accused,
    R.M.C. 603(d). Finally, Rule 801(d) on “[u]ncharged
    offenses” provides that, “[i]f during the trial there is evidence
    that the accused may be guilty of an untried offense not
    alleged in any specification before the commission, the
    commission shall proceed with the trial of the offense
    charged.” R.M.C. 801(d) (emphasis added). Upholding al
    Bahlul’s conviction on the ground that he could have been
    tried for and convicted of some other offense would, at the
    least, raise serious questions as to whether this court has
    departed from Congress’s express instructions regarding the
    rights and procedural protections to which alien enemy
    belligerents are entitled.
    Even if that were not enough, our colleagues’ approach
    would usurp the fact-finding role of the military commission
    members, see 10 U.S.C. § 949l; R.M.C. 502(a)(2) (“The
    members of a military commission shall determine whether
    the accused is proved guilty . . . .”); R.M.C. 921 (addressing
    the members’ responsibility to determine guilt with respect to
    each charge and specification), and transgress the statutory
    limits on this court’s appellate review. Perhaps most
    importantly, this court’s authority under the MCA is limited
    to “approv[ing]” a finding of guilty or “affirm[ing] . . . so
    much of the finding as includes a lesser included offense.” 10
    60
    U.S.C. § 950a; see 
    id. § 950g.
    The offenses our colleagues
    glimpse in the record are neither the charged inchoate
    conspiracy nor lesser-included offenses of that crime. See
    Kelly v. United States, 
    370 F.2d 227
    , 228 (D.C. Cir. 1966);
    FED. R. CRIM. P. 31(c).
    Finally, our colleagues seem to rely on a narrow reading
    of the 2006 MCA’s conspiracy provision as evidence that the
    government really obtained a conviction for al Bahlul’s
    participation in a conspiracy that resulted in completed war
    crimes, an offense that they believe would be triable in a
    military commission because it would be akin to holding an
    individual responsible under international law for completed
    war crimes on a joint criminal enterprise theory of liability.
    They believe that the statute’s reference to “victims,” see 10
    U.S.C. § 950v(b)(28) (2006), requires that there be a
    completed law-of-war offense to convict an individual of
    “conspiracy” within the meaning of that provision, see Millett
    Op. at 30; Wilkins Op. at 9. We think it quite unwise to opine
    on the meaning of the statute’s opaque reference to “victims”
    without the aid of briefing, especially given that, during its
    more than four years of litigating this case, the government
    has never pressed such an interpretation of the statute and has
    instead repeatedly insisted that the statute criminalizes
    inchoate conspiracy. Even if our colleagues are correct, that
    would have no effect on the proper outcome in this case. It
    would only raise additional questions as to whether al
    Bahlul’s trial for the crime of inchoate conspiracy was
    statutorily authorized. The Article III problem lying at the
    heart of this case thus cannot be solved by reimagining the
    statute under which al Bahlul was convicted or the crimes for
    which he was charged, as doing so only raises other
    fundamental legal problems.
    61
    To be sure, Judge Millett and Judge Wilkins’s approach
    would allow us to sustain the conviction of a man who—by
    his own admission—proudly assisted the terrorist group
    responsible for one of the most terrible attacks ever
    perpetrated against the United States. But that approach is
    unavailable to us. The government chose to prosecute al
    Bahlul in a military commission for the crime of inchoate
    conspiracy. It also never suggested that this court can uphold
    al Bahlul’s conviction on the ground that he could have been
    convicted of other charges—and for good reason. That
    approach raises serious due process concerns and conflicts
    with the military-commission procedures Congress requires.
    IV.
    One may wonder, “why the fuss?” Stern v. Marshall, 
    564 U.S. 462
    , 502 (2011). After all, the government is not seeking
    to prosecute cyber or drug crimes before military
    commissions; it is seeking only to prosecute conspiracies to
    commit recognized war crimes. Can such a modest expansion
    of military-commission jurisdiction really threaten the
    Constitution’s separation of powers? As in Stern v. Marshall,
    “[t]he short but emphatic answer is yes.” 
    Id. “[O]ur Constitution
    . . . commands that the independence of the
    Judiciary be jealously guarded . . . .” Northern 
    Pipeline, 458 U.S. at 60
    (plurality opinion). The political branches “may no
    more lawfully chip away at the authority of the Judicial
    Branch than [they] may eliminate it entirely.” 
    Stern, 564 U.S. at 503
    . And “[a]lthough it may be that it is the obnoxious
    thing in its mildest and least repulsive form, we cannot
    overlook the intrusion: illegitimate and unconstitutional
    practices get their first footing in that way, namely, by silent
    approaches and slight deviations from legal modes of
    procedure.” 
    Id. (internal quotation
    marks omitted).
    62
    Here, it is easy to see how allowing the political branches
    to stretch Article III’s exception for law-of-war military
    commissions to encompass inchoate conspiracy charges
    could represent just the first step toward a much greater
    usurpation of the judiciary’s domain. Against the backdrop of
    the war on terror, in which many of the traditional constraints
    on the use of law-of-war military commissions are
    disappearing, the government articulates a breathtakingly
    expansive view of the political branches’ authority to subject
    non-servicemembers to military trial and punishment. Indeed,
    it admits only two constitutional constraints on its power to
    try individuals in law-of-war military commissions: the
    charges must allege (1) that the individuals are “enemy
    belligerents” who (2) engaged in proscribed conduct “in the
    context of and associated with hostilities.” Oral Arg. Tr. 37–
    38 (Dec. 1, 2015).
    Critically, the government’s suggestion that the
    defendant’s status as an enemy belligerent in the context of
    hostilities suffices to subject him to trial by military
    commission ignores the Supreme Court’s focus on the
    offenses triable to law-of-war military commissions, in
    addition to the status of the offenders. Thus the Court has
    focused on “the question whether it is within the
    constitutional power of the national government to place
    petitioners upon trial before a military commission for the
    offenses with which they are charged.” 
    Quirin, 317 U.S. at 2
    9
    (emphasis added). In Quirin, the Court “assume[d] that there
    are acts” that could not be tried by military commission
    “because they are of that class of offenses constitutionally
    triable only by a jury.” 
    Id. (emphases added).
    So, too, in
    
    Yamashita. 327 U.S. at 8
    . And in Hamdan, the Court
    explained that the status of the offender (being a member of a
    foreign armed force) and the nature of the offense were both
    necessary conditions for the exercise of jurisdiction by a law-
    63
    of-war military commission. See 
    Hamdan, 548 U.S. at 597
    –
    98 (plurality opinion) (citing WINTHROP, MILITARY 
    LAW, supra, at 836
    –39); accord 
    id. at 683
    (Thomas, J., dissenting).
    But putting that aside, the extent to which the
    government’s proposed limits have any force is far from
    clear. What does it mean, for instance, for an individual to
    have committed an offense in the context of hostilities? The
    answer is uncertain, both as a temporal and geographic
    matter. We would be willing to wager that if you asked
    Americans when the United States’ “war” with al Qaeda
    began, most would say September 11, 2001. Even executive
    branch officials often cite that date as the beginning of
    hostilities against al Qaeda and its affiliates. For example, for
    certain naturalization purposes, the President “designate[d] as
    a period in which the Armed Forces of the United States were
    engaged in armed conflict with a hostile foreign force the
    period beginning on September 11, 2001.” E.O. 13,269, 67
    Fed. Reg. 45,287 (July 3, 2002); see Memorandum for the
    Attorney General, from Jay S. Bybee, Assistant Attorney
    General, Office of Legal Counsel, Re: Determination of
    Enemy Belligerency and Military Detention (June 8, 2002),
    available at 
    2002 WL 34482990
    , at *7 (“[T]he September 11,
    2001 attacks on the World Trade Center and the Pentagon
    began an international armed conflict between the United
    States and the al Qaeda terrorist organization.”). But in a
    pending military-commission case, the government seeks to
    hold an alleged member of al Qaeda responsible for a failed
    attack on a U.S. vessel that occurred in January 2000. It takes
    the position in that case that the United States’ war with al
    Qaeda goes back “to at least 1998,” and it appears to believe
    that the conflict may date as far back as 1992. See Brief for
    the United States 5, 41, United States v. Al-Nashiri, Nos. 15-
    5020 & 15-1023 (D.C. Cir. Dec. 28, 2015). But see United
    States v. Al-Nashiri, --- F.3d --- (D.C. Cir. 2016) (recognizing
    64
    as unsettled for purposes of mandamus when hostilities began
    against Al Qaeda).
    If the government’s view in this case that military
    commission jurisdiction is limited only by Congress’ war
    powers were to prevail, Congress and the President could
    authorize military prosecutions in many situations that we
    traditionally think of as within the exclusive province of
    domestic law enforcement agencies and civilian courts.
    Suppose, for instance, that the FBI launches an investigation
    into three lawful permanent residents who have lived in the
    United States since early childhood. Searching an apartment
    in Virginia that the three share, it discovers pipe bombs, al
    Qaeda propaganda, and a map of the Washington, D.C. metro
    system. The government arrests the three and wishes to
    prosecute them for conspiracy to kill innocent civilians.
    Under the government’s view of things, the Constitution
    would pose no bar to transferring the individuals into military
    custody and prosecuting them before a military commission.
    In fact, when presented with this hypothetical at oral
    argument, government counsel conceded that these facts
    “might well be enough” to try the individuals in a military
    tribunal. Oral Arg. Tr. 51–53 (Dec. 1, 2015); see also
    Kavanaugh Op. at 30–31. This is a dangerous suggestion to
    say the least. Cf. 
    Reid, 354 U.S. at 23
    –24 (plurality opinion)
    (“The Founders envisioned the army as a necessary
    institution, but one dangerous to liberty if not confined within
    its essential bounds.”).
    But the government’s position gets more dangerous still.
    Now suppose that the three are U.S. citizens. Could the
    government do an end run around Article III solely because
    they had some connection to the “war” on terrorism? It would
    seem so. See 
    Quirin, 317 U.S. at 37
    –38 (holding that a
    saboteur’s U.S. citizenship was irrelevant to a commission’s
    65
    authority to try him for law-of-war offenses). What if the FBI
    instead discovered that the three U.S. citizens sent $200 to the
    humanitarian wing of an organization that the United States
    designated a foreign terrorist organization, earmarked for
    training in human-rights advocacy that the donors hope will
    turn the organization away from terrorist activities? Could the
    three be shipped off to a military base and tried for material
    support for terrorism—an offense unrecognized under
    international law but made punishable under the Military
    Commissions Act? 10 U.S.C. § 950t(25); cf. Holder v.
    Humanitarian Law Project, 
    561 U.S. 1
    , 7–11 (2010). The
    government seems to think so.
    According to Judge Kavanaugh’s opinion, the court need
    not concern itself with the limits (or lack thereof) on the
    political branches’ authority to make conduct punishable by
    military commission because whatever those limits might be,
    the punishment of conspiracies to commit war crimes
    certainly falls within them. See Kavanaugh Op. at 25. But if
    international law does not mark the boundaries between
    civilian and military jurisdiction, what does? On this, our
    colleagues are silent. Based on the principles articulated by
    the government and embraced in Judge Kavanaugh’s opinion,
    however, it would seem that Congress and the President could
    vest military commissions with authority to try enemy
    belligerents for almost any crime so long as it related in some
    way to “hostilities.” 
    Id. at 24–25.
    Especially in this new era
    of “war” against difficult-to-identify enemies on difficult-to-
    identify “battlefields,” such positions would appear to leave
    few, if any, enforceable limits on the political branches’
    authority to avoid Article III courts and prosecute individuals
    in military commissions. Thus, although allowing military
    commissions to take cognizance of inchoate conspiracy
    charges might seem to some a small and harmless
    encroachment on the judiciary’s domain, it could very well
    66
    open the door to much broader intrusions. Any such intrusion
    would be all the more pernicious here and corrosive of Article
    III given that, in this case, the government has made no effort
    to demonstrate the “military necessity” that has traditionally
    been a prerequisite to resort to military commissions.
    
    Hamdan, 548 U.S. at 590
    ; see also 
    id. at 598–99
    (plurality
    opinion); 
    id. at 646
    (Kennedy, J., concurring). To accept the
    government’s position would embed the use of military
    commissions “more deeply in our law and thinking,” ready to
    be “expand[ed] . . . to new purposes.” Korematsu v. United
    States, 
    323 U.S. 214
    , 246 (1944) (Jackson, J. dissenting). A
    majority of this court declines today to deal any such “blow to
    liberty.” 
    Id. * *
       *
    Before concluding, we think it worth underscoring the
    result of today’s decision. Eight of the nine judges deciding
    this appeal believe that the question lying at the heart of it,
    i.e., whether Congress can lawfully vest military commissions
    with jurisdiction over the crime of inchoate conspiracy, is
    deserving of de novo review. Only four of those considering
    the question de novo answer it in the affirmative.
    Accordingly, the majority of judges declines to endorse the
    government’s view of the Constitution. Today’s decision thus
    provides no precedential value for the government’s efforts to
    divert the trial of conspiracy or any other purely domestic
    crime to law-of-war military commissions.
    We, for the reasons discussed, see no lawful basis for the
    government’s claimed power. Whatever deference the
    judiciary may owe to the political branches in matters of
    national security and defense, it is not absolute. Far from it, it
    is the duty of the courts “in time of war as well as in time of
    peace, to preserve unimpaired the constitutional safeguards of
    67
    civil liberty.” 
    Quirin, 317 U.S. at 19
    . And although the
    government might well be entitled to detain al Bahlul as an
    enemy belligerent, see 
    Hamdi, 542 U.S. at 518
    –24 (plurality
    opinion), it does not have the “power to switch the
    Constitution on and off at will,” 
    Boumediene, 553 U.S. at 766
    .
    Its prosecution of al Bahlul in a military commission for
    conspiracy to violate the laws of war exceeded the scope of
    Article III’s exception for law-of-war military commissions
    and, as a result, violated Article III. Accordingly, we would
    vacate his conspiracy conviction.
    

Document Info

Docket Number: 11-1324

Citation Numbers: 840 F.3d 757

Filed Date: 10/20/2016

Precedential Status: Precedential

Modified Date: 1/12/2023

Authorities (121)

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