In re: Republic of Hungary ( 2022 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued October 7, 2021                 Decided March 8, 2022
    No. 20-7047
    DAVID L. DE CSEPEL, ET AL.,
    APPELLEES
    v.
    REPUBLIC OF HUNGARY, A FOREIGN STATE, ET AL.,
    APPELLANTS
    Appeal from the United States District Court
    for the District of Columbia
    (No. 1:10-cv-01261)
    No. 20-8001
    IN RE: REPUBLIC OF HUNGARY, ET AL.,
    PETITIONERS
    Petition and Cross-Petition for Permission to Appeal Under
    
    28 U.S.C. § 1292
    (b) from an Interlocutory Order of the
    United States District Court for the District of Columbia
    (No. 1:10-cv-01261)
    2
    Thaddeus J. Stauber argued the cause for appellants. With him
    on the briefs was Sarah Erickson André.
    Alycia Regan Benenati argued the cause for appellees. With her
    on the brief were Sheron Korpus and David E. Mills.
    Before: TATEL, PILLARD, and JACKSON*, Circuit Judges.
    Opinion for the court filed by Circuit Judge TATEL and
    Circuit Judge PILLARD.
    TATEL and PILLARD, Circuit Judges: For the third time, we
    consider a family’s decades-long effort to recover a valuable
    art collection that the World War II-era Hungarian government
    and its Nazi collaborators seized during their wholesale plunder
    of Jewish property during the Holocaust. On remand from our
    second decision, the district court dismissed the family’s
    claims against the Republic of Hungary and permitted the suit
    to proceed against the remaining defendants, a Hungarian asset
    management company, a university, and three art museums.
    The remaining defendants appeal the district court’s denial of
    sovereign immunity, and the parties also seek our discretionary
    review of additional issues. For the reasons explained below,
    we exercise that discretion to review several holdings, and
    we affirm the district court on those that we review.
    I.
    We described the background of this case in our earlier
    opinions, de Csepel v. Republic of Hungary, 
    714 F.3d 591
    ,
    594–97 (D.C. Cir. 2013) (de Csepel I) and de Csepel v.
    Republic of Hungary, 
    859 F.3d 1094
    , 1097–99 (D.C. Cir. 2017)
    (de Csepel II). For the reader’s convenience, we repeat it
    *
    Circuit Judge Jackson was a member of the panel at the time the
    case was argued but did not participate in this opinion.
    3
    virtually in full. Baron Mór Lipót Herzog was a “passionate
    Jewish art collector in pre-war Hungary” who assembled a
    collection of more than two thousand paintings, sculptures, and
    other artworks. Am. Compl. ¶ 37. Known as the “Herzog
    Collection,” this body of artwork was “one of Europe’s great
    private collections of art, and the largest in Hungary,” and
    included works by renowned artists such as El Greco,
    Velázquez, Renoir, and Monet. 
    Id.
     Following Herzog’s death
    in 1934 and his wife’s shortly thereafter, their daughter
    Erzsébet and two sons István and András inherited the
    collection. 
    Id. ¶ 38
    .
    Then came World War II, and Hungary joined the Axis
    Powers. In March 1944, Adolf Hitler sent German troops into
    Hungary, and SS Commander Adolf Eichmann entered the
    country along with the occupying forces and established
    headquarters at the Majestic Hotel in Budapest. 
    Id. ¶¶ 50
    , 51
    59. During this time, Hungarian Jews were subjected to anti-
    Semitic laws restricting their economic and cultural
    participation in Hungarian society and deported to German
    concentration camps. 
    Id. ¶¶ 43, 46, 51
    . As an integral part of
    its oppression of Hungarian Jews, “[t]he Hungarian
    government, including the Hungarian state police, authorized,
    fully supported and carried out a program of wholesale plunder
    of Jewish property, stripping anyone ‘of Jewish origin’ of their
    assets.” 
    Id. ¶ 53
    . Jews “were required to register all of their
    property and valuables” in excess of a certain value, and the
    Hungarian government “inventoried the contents of safes and
    confiscated cash, jewelry, and other valuables belonging to
    Jews.” 
    Id. ¶ 54
    . “[P]articularly concerned with the retention of
    artistic treasures belonging to Jews,” the Hungarian
    government established “a so-called Commission for the
    Recording and Safeguarding of Impounded Art Objects of Jews
    . . . and required Hungarian Jews promptly to register all art
    objects in their possession.” 
    Id. ¶ 55
    . “These art treasures were
    4
    sequestered and collected centrally by the Commission for Art
    Objects,” headed by the director of the Hungarian Museum of
    Fine Arts. 
    Id.
    In response to widespread looting of Jewish property, the
    Herzogs “attempted to save their art works from damage and
    confiscation by hiding the bulk of [them] in the cellar of one of
    the family’s factories at Budafok.” 
    Id. ¶ 57
    . Despite these
    efforts, “the Hungarian government and their Nazi[]
    collaborators discovered the hiding place” and confiscated the
    artworks. 
    Id. ¶ 58
    . They were “taken directly to Adolf
    Eichmann’s headquarters at the Majestic Hotel in Budapest for
    his inspection,” where he “selected many of the best pieces of
    the Herzog Collection” for display near Gestapo headquarters
    and for eventual transport to Germany. 
    Id. ¶ 59
    . “The
    remainder was handed over by the Hungarian government to
    the Museum of Fine Arts for safekeeping.” 
    Id.
     After seizure of
    the collection, a pro-Nazi newspaper ran an article in which the
    director of the Hungarian Museum of Fine Arts boasted that the
    “‘Herzog collection contains treasures the artistic value of
    which exceeds that of any similar collection in the country. . . .
    If the state now takes over these treasures, the Museum of Fine
    Arts will become a collection ranking just behind Madrid.’” 
    Id. ¶ 58
    .
    “Fearing for their lives, and stripped of their property and
    livelihoods, the Herzog family was forced to flee Hungary or
    face extermination.” 
    Id. ¶ 62
    . Erzsébet Herzog (Erzsébet Weiss
    de Csepel following her marriage) fled Hungary with her
    children, first reaching Portugal and eventually settling in the
    United States, where she became a U.S. citizen in 1952. 
    Id.
    István Herzog was nearly sent to Auschwitz but “escaped after
    his former sister-in-law’s husband . . . arranged for him to be
    put in a safe house under the protection of the Spanish
    Embassy.” 
    Id. ¶ 41
    . “He died in 1966, leaving his estate to his
    5
    two sons, Stephan and Péter Herzog, and his second wife,
    Mária Bertalanffy.” 
    Id.
     András Herzog was “sent . . . into
    forced labor in 1942 and he died on the Eastern Front in 1943.”
    
    Id. ¶ 40
    . His daughters, Julia Alice Herzog and Angela Maria
    Herzog, fled to Argentina and eventually settled in Italy. 
    Id. ¶¶ 40, 63
    .
    Following the end of World War II, the Herzog family
    began a seven-decade effort to reclaim the art collection,
    including through the Hungarian courts. de Csepel II, 859 F.3d
    at 1098. When those efforts proved unsuccessful, three heirs to
    the collection — Erzsébet’s son David L. de Csepel, along with
    András’s daughters Julia Alice and Angela Maria Herzog
    (collectively, “the family”) — filed suit in U.S. district court.
    The family brought the suit against the Republic of Hungary,
    three art museums — the Budapest Museum of Fine Arts, the
    Hungarian National Gallery, and the Budapest Museum of
    Applied Arts — and the Budapest University of Technology
    and Economics. Compl. ¶¶ 9–13. The family alleges that
    Defendants’ possession or re-possession of at least forty pieces
    of the Herzog Collection following World War II “constituted
    one or more express or implied bailment contracts” and that
    Defendants’ failure to return the artworks upon demand
    breached the bailment contracts and constituted conversion and
    unjust enrichment. Am. Compl. ¶¶ 16, 99–123, 139–142. The
    family seeks imposition of a constructive trust, an accounting,
    and a declaration of its ownership of the Herzog Collection, all
    aimed at either recovering the artwork or obtaining over $100
    million in compensation. Id. ¶¶ 124–38 & pt. V.
    This dispute first arrived in our court in 2013, and the
    question before us then was whether the suit was barred by the
    Foreign Sovereign Immunities Act (“FSIA”). de Csepel I, 714
    F.3d at 597. “That Act authorizes federal jurisdiction over civil
    actions against foreign states, as relevant here, only in certain
    6
    cases involving expropriated property or commercial activity,
    and only to the extent such jurisdiction is not inconsistent with
    certain international agreements.” de Csepel II, 859 F.3d at
    1099 (citing 
    28 U.S.C. §§ 1604
    –05). We rejected Defendants’
    assertion of sovereign immunity, concluding on the pleadings
    that the family’s claims satisfied the FSIA’s commercial
    activity exception and that jurisdiction was not inconsistent
    with agreements between the United States and Hungary. de
    Csepel I, 714 F.3d at 597–603.
    This dispute returned to our court after the district court,
    following the close of discovery, concluded that, as the
    evidentiary record had developed, the commercial activity
    exception did not apply but the action could nonetheless
    proceed under the FSIA’s expropriation exception. de Csepel
    II, 859 F.3d at 1099. We affirmed the district court’s
    conclusion that the expropriation exception applied to “twenty-
    five or so artworks taken by Hungary during the Holocaust and
    never returned.” Id. at 1103. But we remanded for the district
    court to consider whether the expropriation exception applies
    to nineteen artworks that were temporarily returned to
    members of the Herzog family. Id. at 1103–04. We instructed
    the district court to (1) dismiss the Republic of Hungary
    because it enjoys immunity under the FSIA and (2) “grant the
    Herzog family leave to amend their complaint in light of the
    Holocaust Expropriated Art Recovery Act” of 2016 (“HEAR
    Act”). Id. at 1107, 1110.
    Back in the district court, the family filed an amended
    complaint that referenced the HEAR Act and added a new
    defendant, Hungarian National Asset Management Inc.
    (“MNV”), which exercises ownership rights over and manages
    certain Hungarian assets. Am. Compl. ¶¶ 3, 14, 87–98. The
    district court dismissed the Republic of Hungary in accordance
    with our directive, and rejected Defendants’ arguments that
    7
    MNV is not a proper party to this suit and that this action may
    not proceed against the remaining defendants in Hungary’s
    absence. de Csepel v. Republic of Hungary, No. 10-cv-01261,
    
    2020 WL 2343405
    , at *5–6, 10, 17, 33 (D.D.C. May 11, 2020)
    (Remand II). The court retained jurisdiction over five of the
    nineteen artworks that were temporarily returned to the Herzog
    family, holding that the FSIA’s expropriation exception
    applied to these pieces. 
    Id. at *19, 35
    .
    Defendants now appeal, seeking dismissal of the family’s
    suit in its entirety. They argue that MNV is shielded by
    Hungary’s sovereign immunity, that the district court violated
    this court’s mandate in de Csepel II by allowing amendment of
    the complaint to add Defendant MNV, that Federal Rule of
    Civil Procedure 19 bars this action from continuing against the
    remaining defendants, that the principle of prudential
    exhaustion requires dismissal of this action, and that the district
    court lacks jurisdiction regarding the five artworks that were
    temporarily returned to the family. The family defends the
    district court’s decision but asks that, should we review
    whether the court properly exercised jurisdiction over the five
    artworks, we also consider whether the district court erred in
    dismissing claims to twelve of the other fourteen artworks for
    lack of jurisdiction.
    We have appellate jurisdiction to consider whether MNV
    is immune from suit under the FSIA. de Csepel II, 859 F.3d at
    1099 (“It is . . . well settled that denial of a motion to dismiss
    on the ground of sovereign immunity is ‘final’ by application
    of the collateral order doctrine and ‘therefore subject to
    interlocutory review.’” (citation omitted)). Because the district
    court certified its order for immediate appellate review, we also
    have discretion to consider Defendants’ remaining arguments,
    and we explain below the extent to which we exercise that
    discretion and our corresponding dispositions. See 28 U.S.C.
    8
    1292(b) (permitting an appellate court to, “in its discretion,”
    consider an interlocutory appeal where the district judge
    certifies that the “order involves a controlling question of law
    as to which there is substantial ground for difference of opinion
    and that an immediate appeal from the order may materially
    advance the ultimate termination of the litigation”); Walsh v.
    Ford Motor Co., 
    807 F.2d 1000
    , 1002 n.2 (D.C. Cir. 1986)
    (holding that, where a district court certifies an issue for appeal,
    the court of appeals “must decide all questions of law necessary
    to the proper disposition of [the] appeal”).
    II.
    The family’s amended complaint added MNV, a state-
    owned company that exercises Hungary’s ownership rights
    over certain governmental assets, including the artworks at
    issue in this case. Am. Compl. ¶¶ 14, 36. Defendants argue that
    MNV is entitled to sovereign immunity and that the district
    court violated this court’s mandate in de Csepel II by
    permitting the family to add MNV to its amended complaint.
    The FSIA provides that a foreign state, including any
    political subdivision, agency, or instrumentality thereof, “shall
    be immune from the jurisdiction of the courts of the United
    States” subject to certain exceptions. 
    28 U.S.C. § 1604
    ; see 
    id.
    § 1603(a). Under the expropriation exception, a foreign
    sovereign loses its immunity if “‘rights in property taken in
    violation of international law are in issue,’” and “there is an
    adequate commercial nexus between the United States and the
    defendants.” de Csepel II, 859 F.3d at 1101 (quoting 
    28 U.S.C. § 1605
    (a)(3)). The commercial-activity nexus requirement is
    met if (1) the property in issue “is present in the United States
    in connection with a commercial activity carried on in the
    United States by the foreign state” or (2) that property “is
    owned or operated by an agency or instrumentality of the
    9
    foreign state and that agency or instrumentality is engaged in a
    commercial activity in the United States.” 
    28 U.S.C. § 1605
    (a)(3). As we explained in de Csepel II, “[a] foreign
    state loses its immunity if the claim against it satisfies the
    exception by way of the first clause of the commercial-activity
    nexus requirement; by contrast, an agency or instrumentality
    loses its immunity if the claim against it satisfies the exception
    by way of the second clause.” de Csepel II, 859 F.3d at 1107
    (emphasis added); Simon v. Republic of Hungary, 
    812 F.3d 127
    , 146 (D.C. Cir. 2016) (holding that the first clause applies
    to claims against the foreign state itself, whereas the second
    clause applies to claims against an agency or instrumentality of
    the foreign state).
    The Herzog Collection is located outside the United States,
    so the family’s claims fall within the expropriation exception
    only if the Collection is owned or operated by an “agency or
    instrumentality” of Hungary. See de Csepel II, 859 F.3d at 1107
    (describing the application of the expropriation exception to an
    “agency or instrumentality” versus the “foreign state” itself).
    Defendants do not contest that they are “engaged in a
    commercial activity in the United States.” See de Csepel II, 859
    F.3d at 1104. Thus, whether the family may invoke this
    exception to establish federal jurisdiction over MNV turns on
    whether MNV is an agency or instrumentality of Hungary or,
    rather, the foreign state itself. The family argues that MNV is
    an agency or instrumentality of Hungary, as evidenced by
    MNV’s commercial functions analogous to those performed by
    private entities. Defendants argue that MNV is “a ‘Political
    Organ’ of the Hungarian State” and, as such, constitutes the
    foreign state itself. Appellants’ Br. 18.
    Because the family asserts jurisdiction under the FSIA and
    Defendants assert the jurisdictional defense of immunity,
    Defendants bear the burden of proving that the family’s
    10
    allegations do not bring this case within a statutory exception
    to immunity. Belize Social Development Ltd. v. Government of
    Belize, 
    794 F.3d 99
    , 102 (D.C. Cir. 2015). And because
    Defendants “challenge[] the factual basis of the court’s
    jurisdiction, . . . the court must go beyond the pleadings and
    resolve any disputed issues of fact the resolution of which is
    necessary to a ruling upon the motion to dismiss.” Phoenix
    Consulting Inc. v. Republic on Angola, 
    216 F.3d 36
    , 40 (D.C.
    Cir. 2000). Our review is de novo. de Csepel II, 859 F.3d at
    1099.
    To determine whether MNV is an agency or
    instrumentality of Hungary or, rather, Hungary itself, we
    consider whether its “core functions . . . are governmental or
    commercial.” Transaero, Inc. v. La Fuerza Aerea Boliviana,
    
    30 F.3d 148
    , 153 (D.C. Cir. 1994). If MNV’s core functions
    are “commercial, the entity is an agency or instrumentality;” if
    MNV’s core functions are “governmental, it is considered the
    foreign state itself.” Roeder v. Islamic Republic of Iran, 
    333 F.3d 228
    , 234 (D.C. Cir. 2003).
    Applying this “core functions” test, we have held that
    Bolivia’s Air Force and Iran’s Ministry of Foreign Affairs are
    the foreign states themselves rather than agencies or
    instrumentalities. Transaero, 
    30 F.3d at 153
     (Bolivia’s Air
    Force); Roeder, 
    333 F.3d at 234
     (Iran’s Ministry of Foreign
    Affairs). As we have explained, “[t]he conduct of foreign
    affairs is an important and indispensable governmental
    function,” Roeder, 
    333 F.3d at
    234–35 (internal quotation
    marks omitted), and “[t]he powers to declare and wage war are
    among the necessary concomitants of sovereignty,” Transaero,
    
    30 F.3d at 153
     (internal quotation marks omitted). Such
    entities, therefore, “clearly” fall on the “governmental side.”
    Roeder, 
    333 F.3d at 234
    .
    11
    Although our court has not previously held an entity to be
    an agency or instrumentality under the core functions test, our
    colleagues on the district court have held that a South Korean
    cultural foundation and a Russian library and military archive
    are state agencies or instrumentalities. See Smith v. Overseas
    Korean Cultural Heritage Foundation, 
    279 F. Supp. 3d 293
    ,
    297 (D.D.C. 2018); Agudas Chasidei Chabad of United States
    v. Russian Federation, 
    729 F. Supp. 2d 141
    , 147 (D.D.C.
    2010). As the district court has explained, the tasks performed
    by these entities — the construction and operation of a museum
    and the reproduction and sale of books and manuscripts — are
    commercial actions in which private parties regularly engage.
    Smith, 279 F. Supp. 3d at 297 (“building and operating a
    museum . . . is commercial in nature”); Agudas, 
    729 F. Supp. 2d at 148
     (reproducing, selling, and distributing books and
    manuscripts are “commercial activit[ies]”).
    Whether MNV’s core functions are governmental or
    commercial is less clear. Under Hungarian law, MNV exercises
    the “ownership rights and obligations belonging to the State
    over state assets entrusted to it.” Hungarian Act CVI of 2007
    on State Assets (“State Property Act”) § 3(1), Joint Appendix
    (J.A.) 2975. It “prepare[s] and/or execute[s] the decisions of
    Parliament, the Government and the minister relating to state
    assets,” “keep[s] records on state assets,” “inspect[s] the
    operations involving state assets of the persons, organisations
    or other users that are in a contractual relationship with
    [MNV],” and “oversee[s] the fulfilment of obligations set out
    in the sales contracts.” State Property Act § 17(1), J.A. 2977.
    Unlike entities that conduct foreign affairs or military
    operations, MNV performs property management functions
    that private entities also perform. See Republic of Argentina v.
    Weltover Inc., 
    504 U.S. 607
    , 614 (1992) (“[T]he foreign
    sovereign’s actions are commercial within the meaning of the
    FSIA” when they “are the type of actions by which a private
    12
    party engages in trade and traffic or commerce.” (internal
    quotation marks omitted)). By contrast, a sovereign cannot
    function without property, and ownership of certain types of
    property, like public lands, is uniquely governmental. See 
    id.
    (A foreign government’s activities are “sovereign” rather than
    “commercial” when they are activities that “cannot be
    exercised by a private party.” (internal quotation marks
    omitted)). Given the myriad types of property that can be held
    privately or as state assets, we cannot conclude that the
    function of holding and managing property, in and of itself, is
    “so closely bound up with the structure of the state that [it] must
    in all cases be considered” a governmental rather than
    commercial function. Transaero, 
    30 F.3d at 153
    . Instead,
    whether the management of state property is governmental or
    commercial depends on the type of property at issue.
    MNV manages state-owned companies, “movable
    propert[y],” and real property. Declaration of Dr. Bernadette
    Somody 5–6, de Csepel v. Hungary, No. 10-cv-01261 (D.D.C.
    Mar. 23, 2018), ECF No. 153-1, J.A. 3234–35. It exercises
    ownership rights over about 450 companies, including “a major
    Hungarian energy group,” “the largest gambling service
    provider in Hungary,” and a “waste management” holding
    company. 
    Id.
     MNV also manages almost 100,000 state-owned
    movable properties, including “road vehicles,” “musical
    instruments,” and “works of art.” Id. at 6, J.A. 3235. As for its
    management of real property, MNV’s “main duty . . . is to
    provide real estate for the performance of state functions and
    for meeting public demand.” Id. There is nothing inherently
    sovereign about managing energy, gambling, or waste. Nor are
    the acts of maintaining and lending road vehicles, musical
    instruments, or art pieces governmental in nature, even when
    these items belong to a sovereign. Indeed, our own district
    court has held that the act of lending art pieces is commercial,
    noting that “[l]oans between and among museums (both public
    13
    and private) occur around the world regularly.” Malewicz v.
    City of Amsterdam, 
    362 F. Supp. 2d 298
    , 314 (D.D.C. 2005).
    Finally, although providing real estate for state functions
    appears governmental, providing real estate to “meet[] public
    demand” is a function routinely performed by private real
    estate developers. MNV’s core functions, then, are
    predominantly commercial rather than governmental. See
    Transaero, 
    30 F.3d at 151
     (The question is “whether the core
    functions of the foreign entity are predominantly governmental
    or commercial.”).
    Defendants point out that Hungary’s State Property Act
    provides that “‘[t]he tasks conferred upon MNV . . . [are]
    government functions.’” Appellants’ Br. 19 (quoting State
    Property Act § 17(2), J.A. 2977). Although “MNV may engage
    in certain activities that might be considered ‘commercial’ in
    nature,” Defendants argue, MNV does so “‘within the
    framework of government functions,’” as specified by the State
    Property Act. Id. at 19–20 (quoting State Property Act
    § 17(1)(h), J.A. 2977). But if simply labeling MNV’s activities
    as “governmental” were sufficient under the core functions
    test, the test would be highly manipulable; any foreign
    sovereign wishing to insulate an agency or instrumentality
    from suit could simply declare that the entity’s functions are
    “government functions.”
    Defendants analogize MNV to the Polish Ministry of
    Treasury, which the Second Circuit held in Garb v. Republic of
    Poland constituted the Polish state itself rather than an agency
    or instrumentality of Poland. 
    440 F.3d 579
    , 598 (2d Cir. 2006).
    Defendants’ comparison is unpersuasive. Garb held that the
    Ministry of Treasury’s “core function — to hold and administer
    the property of the Polish state — [was] indisputably
    governmental.” 
    Id. at 594
    . Beyond this statement, Garb neither
    indicated what types of property the Ministry managed nor
    14
    explained why the Ministry’s management of property was
    governmental in nature. As noted above, holding and
    administering property is not per se governmental due to the
    myriad property types that private and public entities alike can
    hold and manage. Without any indication of the type of
    property that the Polish Ministry administered, we cannot
    determine whether that entity is comparable to MNV.
    Because MNV’s management of companies, movable
    property, and real property is overwhelmingly commercial in
    nature, we conclude that MNV is an agency or instrumentality
    of Hungary rather than the foreign state itself. As such, MNV
    falls within the FSIA’s expropriation exception.
    Having concluded that the district court properly exercised
    jurisdiction over MNV, we turn to Defendants’ argument that,
    by permitting the family to add MNV to its amended
    complaint, the district court violated our directive in de Csepel
    II to “grant the Herzog family leave to amend their complaint
    in light of the Holocaust Expropriated Art Recovery Act.” de
    Csepel II, 859 F.3d at 1110. Under the law-of-the-case
    doctrine, courts may not revisit issues already decided
    “‘explicitly or by necessary implication’” in the same case.
    Independent Petroleum Association of America v. Babbitt, 
    235 F.3d 588
    , 597 (D.C. Cir. 2001) (quoting LaShawn A. v. Barry,
    
    87 F.3d 1389
    , 1394 (D.C. Cir. 1996) (en banc)). But, as the
    district court observed, the issue whether the family could add
    MNV to the amended complaint was not before us in de Csepel
    II, nor was it decided by necessary implication. Remand II,
    
    2020 WL 2343405
    , at *6. Our decision to allow the family to
    amend its complaint in one respect did not preclude the family
    from amending it in other respects. Cf. United States v.
    Kennedy, 
    682 F.3d 244
    , 253–54 (3d Cir. 2012) (holding that
    where the court of appeals “qualif[ied its] mandate with the
    term ‘only,’” the district court “ventured beyond the scope of
    15
    [the] mandate” by considering extraneous issues).
    Accordingly, the family’s addition of MNV in its amended
    complaint did not contravene this court’s mandate in de Csepel
    II. As the district court concluded, MNV is a proper party to
    this suit.
    III.
    Defendants also challenge the district court’s denial of
    their Rule 12(b)(7) motion to dismiss for failure to join an
    indispensable party. See Remand II, 
    2020 WL 2343405
    , at
    *12–17 (citing FED. R. CIV. P. 19(a)–(b)). The district court
    held that even assuming Hungary was a “required” party, it is
    not indispensable because this suit may proceed “in equity and
    good conscience” without it. 
    Id.
     “We review the district court’s
    application of Rule 19(b)’s equity and good conscience test for
    abuse of discretion, but questions of law that inform a district
    court’s Rule 19 determination are reviewed de novo.” Nanko
    Shipping, USA v. Alcoa, Inc., 
    850 F.3d 461
    , 465 (D.C. Cir.
    2017) (cleaned up).
    We conclude that Hungary qualifies as a required party,
    but we also affirm the district court’s well-reasoned
    determination that this action may proceed among the existing
    parties “in equity and good conscience.” FED. R. CIV. P. 19(b).
    Hungary’s interests are so aligned with those of the remaining
    defendants that their participation in the litigation protects
    Hungary against potential prejudice from the suit proceeding
    in its absence. Rule 19 thus does not require that the case be
    dismissed.
    As noted above, we have discretion to review issues
    beyond the denial of MNV’s claim of immunity. We exercise
    that discretion to consider the district court’s Rule 19
    determination that this case may proceed in Hungary’s
    absence. This issue involves a controlling question of law
    16
    because it would require reversal if decided incorrectly. There
    are no decisions directly on point in our circuit and, because
    the issue is potentially dispositive of the case, resolving it now
    could avoid unnecessary burdens of further litigation.
    Rule 19 analysis has two steps. We first determine whether
    an absent party is “required,” FED R. CIV. P. 19(a), and, if so,
    we ask “whether, in equity and good conscience, the action
    should proceed among the existing parties or should be
    dismissed.” FED R. CIV. P. 19(b).
    A party is “required” under Rule 19(a)(1) if it meets either
    of two conditions:
    (A) in that person’s absence, the court cannot accord
    complete relief among existing parties; or
    (B) that person claims an interest relating to the subject
    of the action and is so situated that disposing of the
    action in the person’s absence may:
    (i) as a practical matter impair or impede the
    person’s ability to protect the interest; or
    (ii) leave an existing party subject to a
    substantial risk of incurring double, multiple, or
    otherwise inconsistent obligations because of
    the interest.
    FED. R. CIV. P. 19(a)(1).
    Hungary’s interest in the action fits Rule 19(a)(1)(B)’s
    general description, as well as the particular risk identified in
    subclause (B)(i). First, Hungary “claims an interest relating to
    the subject of the action” because it asserts ownership rights
    over the disputed artworks and seeks to avoid liability on the
    17
    family’s claims that Hungary unlawfully took them. See FED.
    R. CIV. P. 19(a)(1)(B); Appellants’ Br. 34–41. Those interests
    raise the question whether Hungary is so situated that
    proceeding in its absence might lead to one of the problems
    identified in subclause (B)(i) or (ii). Defendants invoke
    subclause (B)(i), asserting this litigation might “as a practical
    matter impair or impede [Hungary’s] ability to protect the
    interest[s]” it claims. FED. R. CIV. P. 19(a)(1)(B)(i). Whether
    Hungary has an interest that might be impaired sounds like but
    is importantly distinct from a second inquiry, described below,
    as to whether the remaining parties are positioned to protect
    Hungary’s interests. Rule 19(a) calls for identification of
    potential prejudice, whereas Rule 19(b) requires weighing of
    the risk of prejudice with other factors to make an equitable
    determination whether the case must be dismissed.
    We conclude that deciding the tort-based conversion
    claims in Hungary’s absence could impair its ability to protect
    its asserted interests in the artworks. Generally, under Rule 19
    “it is not necessary for all joint tortfeasors to be named as
    defendants in a single lawsuit.” Temple v. Synthes Corp., 
    498 U.S. 5
    , 7 (1990) (per curiam). But Hungary claims a proprietary
    interest in the same artworks that the family seeks to recover.
    Because Hungary and the family stake out “opposing,
    irreconcilable claims to the same” property, resolving this
    litigation in Hungary’s absence undoubtedly could impede
    Hungary’s ability to protect its interest in such property. See
    Wach v. Byrne, Goldenberg & Hamilton, PLLC, 
    910 F. Supp. 2d 162
    , 169 (D.D.C. 2012) (“[T]he Court easily finds [the
    absent party] to be a ‘required’ party . . . because Plaintiff and
    [the absent party] lay opposing, irreconcilable claims to the
    same portion of the limited settlement proceeds.”); see also
    Brown v. Christman, 
    126 F.2d 625
    , 631 n.23 (D.C. Cir. 1942)
    (“Generally, where the action involves a determination of
    18
    conflicting interests of beneficiaries in a trust fund, the
    beneficiaries are held to be necessary parties.”).
    The contract-based bailment claims have similar potential
    to affect Hungary’s interests. The parties contest whether the
    family’s bailments were with Hungary or with representatives
    of the Hungarian museums. In either event, Hungary claims
    ownership of the same artworks that the family seeks to
    recover. As an absent party, Hungary cannot itself make
    arguments or present evidence in defense of its ownership
    claim. Impaired in its ability to protect interests it asserts here,
    it qualifies as a “required” party for purposes of Rule 19(a).
    That raises the question whether the action may “in equity
    and good conscience” proceed in Hungary’s absence. FED. R.
    CIV. P. 19(b). We answer that question based on Rule 19(b)’s
    four factors:
    (1) the extent to which a judgment rendered in the
    person’s absence might prejudice that person or the
    existing parties;
    (2) the extent to which any prejudice could be lessened
    or avoided by:
    (A) protective provisions in the judgment;
    (B) shaping the relief; or
    (C) other measures;
    (3) whether a judgment rendered in the person’s
    absence would be adequate; and
    (4) whether the plaintiff would have an adequate
    remedy if the action were dismissed for nonjoinder.
    19
    FED. R. CIV. P. 19(b). Application of these factors confirms that
    Hungary is not an indispensable party, so the suit may in equity
    and good conscience proceed in its absence.
    Whether proceeding in Hungary’s absence might
    prejudice Hungary’s interests is the core of the parties’ Rule 19
    dispute. The first Rule 19(b) factor asks whether a party might
    suffer prejudice not simply from an adverse result, but
    specifically from the decision being “rendered in [its]
    absence.” The presence of remaining defendants with interests
    virtually identical to Hungary’s obviates any such risk here.
    Courts recognize that “prejudice to absent parties approaches
    the vanishing point” when “the absent and remaining parties’
    interests are aligned in all respects,” American Trucking Ass’n,
    Inc. v. New York State Thruway Authority, 
    795 F.3d 351
    , 360
    (2d Cir. 2015) (internal quotation marks omitted), including in
    cases in which the absent party is an immune sovereign, see
    Gensetix, Inc. v. Board of Regents of University of Texas
    System, 
    966 F.3d 1316
    , 1326 (Fed. Cir. 2020); Alto v. Black,
    
    738 F.3d 1111
    , 1127 (9th Cir. 2013). The logic is
    straightforward: If a party remaining in the case is both capable
    of and interested in representing the interests of the absent
    party, the party’s exit or exclusion from the suit exposes it to
    no additional risk of an adverse decision.
    Hungary’s interests are closely aligned with those of the
    remaining defendants in this litigation, particularly MNV. The
    allegations and the course of the litigation thus far show that at
    every stage of the case, and even in related litigation twenty
    years ago, MNV has made controlling decisions for all
    defendants, including Hungary. See Remand II, 
    2020 WL 2343405
    , at *15; Am. Compl. ¶ 36, J.A. 499–500; Deposition
    of Dr. Zoltán Molnar 27–28, 45–46, de Csepel v. Hungary, No.
    10-cv-01261 (D.D.C. Mar. 23, 2018), ECF No. 153-24, J.A.
    3529–32. Hungary’s State Property Act appears to require that
    20
    MNV represent Hungary in civil actions involving state
    property. State Property Act § 17(1)(e); Declaration of Zoltán
    Novák 51, de Csepel v. Hungary, No. 10-cv-01261 (D.D.C.
    Mar. 23, 2018), ECF No. 148-29, J.A. 2977. MNV is thus
    “fully able” to “step into [Hungary’s] shoes and protect
    [Hungary’s] interests.” Gensetix, 966 F.3d at 1326. MNV is
    both “capable of and willing to make [all of Hungary’s]
    arguments.” Alto, 738 F.3d at 1127 (internal quotation marks
    omitted).
    Defendants assert that Hungary’s interests are distinct
    insofar as Hungary purports to own the disputed artworks that
    MNV, the museums, and the university merely possess on its
    behalf. Appellants’ Br. 48; Reply Br. 17. But Defendants have
    not identified how that distinction could impair Hungary’s
    interests. At bottom, both Hungary and the remaining
    defendants seek the same result: to retain the artwork and avoid
    any monetary, equitable, or declaratory relief. Defendants thus
    have “the incentive to make every argument on the merits that
    the absent [Hungary] would or could make.” Two Shields v.
    Wilkinson, 
    790 F.3d 791
    , 799 (8th Cir. 2015) (internal
    quotation marks omitted).
    Defendants nonetheless argue that dismissal is compelled
    here by Republic of Philippines v. Pimentel, 
    553 U.S. 851
    (2008). That case was an interpleader action by Merrill Lynch
    in the face of dueling claims to a brokerage account former
    President of the Republic of the Philippines Ferdinand Marcos
    had created with the firm. 
    Id.
     at 857–59. Human rights victims
    sought to enforce a $2 billion default judgment against the
    account, whereas the Philippine government asserted a
    competing claim that the account comprised Marcos’ unlawful
    gains from abuse of office that were properly forfeited to the
    government ab initio. 
    Id.
     The sovereign was a “required” party
    under Rule 19(a), 
    id. at 863
    , so the analysis focused on whether
    21
    under Rule 19(b) the case could proceed “in equity and good
    conscience” without it, 
    id. at 864
    . The Court recognized the
    importance of a sovereign’s “[c]omity and dignity interests”
    under international law, especially in suits arising “from events
    of historical and political significance” for the sovereign. 
    Id. at 866
    . “[W]here sovereign immunity is asserted, and the claims
    of the sovereign are not frivolous,” the Court declared,
    “dismissal of the action must be ordered where there is a
    potential for injury to the interests of the absent sovereign.” 
    Id. at 867
    . That declaration, Defendants assert, spells the end of
    this case.
    Pimentel cannot bear the weight Defendants place on it.
    Pimentel itself reaffirmed that, in assessing the potential for
    injury, the equitable character of Rule 19(b)’s non-exhaustive
    list of factors “indicates that the determination whether to
    proceed will turn upon factors that are case specific.” 
    553 U.S. at
    863–64. Defendants contend that “[b]ecause Hungary (1) is
    an immune sovereign, (2) has a significant interest in its
    cultural patrimony, and (3) is a required party, the action must
    be dismissed.” Appellants’ Br. at 45 (emphasis in original). But
    if the Philippine government’s sovereign interest in the
    disputed issues were alone dispositive in Pimentel, as
    Defendants assert, the Court would have ended the inquiry
    there. Instead, it proceeded to weigh each of the Rule 19(b)
    equitable factors. 
    Id.
     at 865–72.
    Importantly, the Court in Pimentel examined what, if
    anything, might protect the Philippines’ interests were the case
    to proceed in its absence. The key Rule 19(b) factors for that
    purpose were the first two — potential prejudice, and measures
    to mitigate it. As to the potential prejudice from proceeding in
    the Philippines’ absence, the Supreme Court noted that the
    court of appeals had effectively brushed off any sovereign
    interest in claims it thought were likely time barred. The
    22
    Supreme Court deemed that approach impermissible as a
    matter of law:
    [I]t was improper to issue a definitive holding
    regarding a nonfrivolous, substantive claim
    made by an absent, required entity that was
    entitled by its sovereign status to immunity
    from suit. That privilege is much diminished if
    an important and consequential ruling affecting
    the sovereign’s substantial interest is
    determined, or at least assumed, by a federal
    court in the sovereign’s absence and over its
    objection.
    
    Id.
     868–69. On the second factor — the availability of
    measures to lessen or avoid the prejudice — the Court
    determined that there was “no substantial argument” in favor
    of allowing the “action to proceed,” and noted that “[n]o
    alternative remedies or forms of relief have been proposed to
    us or appear to be available.” 
    Id. at 870
    .
    Critically, in Pimentel no party with interests aligned with
    the Philippine government’s remained in the case to guard
    against prejudice in its absence. The interests of the remaining
    defendants — principally the company former President
    Marcos had created to hold the embezzled funds at issue —
    were contrary to those of the Philippine government. And even
    interpleader plaintiff Merrill Lynch had refused an express
    governmental request to place the money in escrow — a step
    that might have mitigated the risk the government faced. 
    Id.
     at
    858–59.
    The parties’ configuration in this case is very different, and
    the Rule 19(b) inquiry here comes out the other way.
    Hungary’s interests are so aligned with those of the remaining
    defendants that the latter will vigorously protect Hungary’s
    23
    interests by pressing their own. The district court
    acknowledged Hungary’s sovereign interests. It spelled out
    why those interests were not at greater risk in Hungary’s
    absence. And it identified how relief could be tailored if needed
    to further reduce any potential prejudice. Remand II, 
    2020 WL 2343405
    , at *14–17. That is the kind of “case specific” analysis
    identifying “substantial argument[s]” for allowing the “action
    to proceed” that Pimentel requires. 
    553 U.S. at 863, 870
    .
    Defendants garner no better support from Kickapoo Tribe
    of Indians of Kickapoo Reservation in Kansas v. Babbitt, 
    43 F.3d 1491
     (D.C. Cir. 1995). There, as in Pimentel but unlike
    here, the interests of the remaining defendants were misaligned
    with those of the absent sovereign. The Kickapoo Tribe sued
    the U.S. Secretary of Interior for failing to timely approve a
    compact it had negotiated with the Governor. 
    Id.
     at 1493–94.
    At the Secretary’s urging, we dismissed that suit under Rule 19
    as unable to proceed in Kansas’s absence.
    Just as we acknowledge that Hungary has an interest here,
    in Kickapoo we started from the premise that “the State of
    Kansas has an interest in the validity of a compact to which it
    is a party, and this interest would be directly affected by the
    relief that the Tribe seeks.” 
    Id. at 1495
    . The problem in
    Kickapoo was that the district court “assumed” that in Kansas’s
    absence the Governor, who remained a party, “ha[d] the best
    interests of the State in mind,” so adequately represented
    Kansas’ interests. 
    Id. at 1497
    . The reality was that the Governor
    had legally defined interests that diverged from the State’s.
    Indeed, the Kansas Supreme Court had squarely ruled that,
    although the Governor could negotiate with the Kickapoo
    Tribe, he lacked authority to finalize binding compacts on
    Kansas’s behalf. 
    Id. at 1494, 1499
    . We accordingly held that
    the district court’s Rule 19(b) analysis, based as it was on
    “assuming that the Governor could adequately represent the
    24
    interests of the State in entering the compact[,] was contrary to
    the controlling state law.” 
    Id. at 1498
    . The mistaken
    assumption that required reversal in Kickapoo is absent here,
    where Hungarian law confirms that the interests of the
    government and the remaining defendants are indeed closely
    aligned.
    Finally, Defendants argue that the suit must be dismissed
    because damages awarded against them would as a practical
    matter ultimately be paid by Hungary. Even if that prediction
    is correct, Defendants’ theory runs aground on two shoals.
    First, Defendants are not themselves entitled to sovereign
    immunity. As discussed above, they fulfill commercial
    functions. Cf. Transaero, 
    30 F.3d at 153
     (explaining that
    entities with commercial core functions are considered
    agencies or instrumentalities rather than foreign states
    themselves); Roeder, 
    333 F.3d at 234
     (same). Hungarian law
    treats them as legal entities separate from the Hungarian
    government, able to sue and be sued on the same terms as
    private entities. Somody Decl. at 2, J.A. 3231. As the district
    court observed, MNV is “not so integral to Hungary’s political
    structure that it should be considered Hungary’s political
    subdivision.” Remand II, 
    2020 WL 2343405
    , at *16 (internal
    quotation marks omitted), J.A. 4071. Rather, all of the
    remaining defendants, as agencies or instrumentalities of
    Hungary, have more limited immunity than the sovereign state
    itself.
    Second, and relatedly, Defendants’ effort to assimilate
    themselves to Hungary based on their assertion that the
    government pays their bills contravenes the FSIA. As
    described above, the expropriation exception has two clauses,
    separately identifying the circumstances under which a foreign
    sovereign may be sued and those that would allow suit against
    25
    a foreign sovereign’s agencies or instrumentalities. 28 U.S.C.
    1605(a)(3). The district court explained how that statutory
    distinction matters here: “If an agency or instrumentality with
    some budgetary ties to the sovereign could never be sued unless
    the sovereign itself were also a party, it would be pointless for
    the FSIA to treat immunity for agencies and instrumentalities
    differently than for foreign states.” Remand II, 
    2020 WL 2343405
    , at *17. A “typical government instrumentality” sued
    under the second clause may, for example, require
    “appropriations to provide capital or to cover losses,” First
    National City Bank v. Banco Para El Comercio Exterior de
    Cuba, 
    462 U.S. 611
    , 624 (1983); see also, e.g., Smith, 279 F.
    Supp. 3d at 296–98; Agudas, 
    729 F. Supp. 2d at
    146–48, but
    that prospect does not serve to collapse the distinction the
    statute reflects.
    Contrary to Defendants’ assertions, see Appellants’ Br. 51,
    the Supreme Court’s decision in Mine Safety Appliances Co. v.
    Forrestal, 
    326 U.S. 371
     (1945), respects that distinction. The
    defendant Secretary of the Navy in that case was the head of a
    political subdivision of the government — not an agency or
    instrumentality — so the Court considered a suit against him
    for payments withheld from the plaintiff, a repeat government
    contractor, as effectively a suit against the sovereign. The
    Secretary withheld the disputed payments to recoup unlawfully
    excessive profits the contractor-plaintiff had received on prior
    contracts. The plaintiff challenged that withholding as “a tort
    by the Secretary, acting as an individual and not as an officer
    of the government, consisting of a trespass against [the
    plaintiff’s] property.” 
    Id. at 373
    . The Court recognized that a
    trespass suit against a government official in his individual
    capacity might not be barred, but that no such case was before
    it. Rather, the “sole purpose” of the claim against Secretary
    Forrestal was to force payment “of money lawfully in the
    26
    United States Treasury to satisfy the government’s and not the
    Secretary’s debt.” 
    Id.
    This case, by contrast, presents the very category of suit
    that Mine Safety would permit. For the reasons explained
    above, each of the defendants is an agency or instrumentality,
    not entitled as was the Secretary of the Navy in Mine Safety to
    partake of the sovereign’s immunity. And here, unlike in Mine
    Safety, the allegations that MNV, the museums, and the
    university are unlawfully withholding the family’s artworks do
    in fact “make out a threatened trespass against [the family’s]
    property” by MNV, the museums, and the university. 
    Id. at 374
    .
    In sum, Hungary’s absence from this litigation does not
    give rise to Rule 19(b) prejudice. Hungary is not likely to suffer
    because its interests are in complete alignment with those of
    the remaining defendants. Hungary’s sovereign interests must
    be “accord[ed] proper weight.” Pimentel, 
    553 U.S. at 869
    . But
    in this case, those interests are not placed at risk due to
    Hungary’s absence. We therefore conclude that this first Rule
    19(b) factor cuts in favor of allowing the suit to proceed.
    The other Rule 19(b) factors similarly weigh in favor of
    the suit proceeding. The second factor directs courts to consider
    ways in which relief might be fashioned to reduce any potential
    prejudice to the absent or remaining parties. FED. R. CIV. P.
    19(b)(2). As the Supreme Court recognized in Pimentel,
    “alternative forms of relief, including the granting of money
    damages rather than specific performance [and] the use of
    declaratory judgment,” may mitigate prejudice to absent
    parties, including sovereigns. 
    553 U.S. at 870
    . Such mitigation
    is available here. The district court observed that “limiting
    plaintiffs’ remedies to damages” as necessary could “further
    reduce[] any prejudice or risk of inconsistent obligations.”
    27
    Remand II, 
    2020 WL 2343405
    , at *15. We do not prematurely
    pass on the necessity of any remedial limitation, but merely
    note that Defendants give no reason to doubt the district court’s
    remedial flexibility.
    On the third factor, we conclude that the court could enter
    “adequate” relief in Hungary’s absence. FED. R. CIV. P.
    19(b)(3). Here, adequacy refers not “to satisfaction of [the
    family’s] claims,” but “to the ‘public stake in settling disputes
    by wholes, whenever possible.’” Pimentel, 
    553 U.S. at 870
    (quoting Provident Tradesmens Bank & Trust Co. v. Patterson,
    
    390 U.S. 102
    , 111 (1968)). As explained above, various stages
    of this litigation have focused on distinct jurisdictional
    questions relating to the various artworks, but the suit as a
    whole seeks full resolution of the family’s claims to the
    relevant artworks. Proceeding with the suit thus promotes “‘the
    efficient administration of justice and the avoidance of multiple
    litigation’” in United States courts. Pimentel, 
    553 U.S. at 870
    (quoting Illinois Brick Co. v. Illinois, 
    431 U.S. 720
    , 738
    (1977)).
    Lastly, we consider whether the family would have any
    opportunity to receive the relief it seeks if this suit were
    dismissed. FED. R. CIV. P. 19(b)(4). If it could not pursue its
    claims in a United States court, the family would be remitted
    to the administrative and judicial processes available in
    Hungary. We agree with the district court that those efforts
    likely “would be futile.” Remand II, 
    2020 WL 2343405
    , at *15.
    Administrative compensation was not available in Hungary
    when the family brought this suit, and the Hungarian court that
    adjudicated the claims of another family member, Martha
    Nierenberg, “determined that returning the paintings to
    Nierenberg was made impossible by customs laws protecting
    cultural patrimony.” de Csepel v. Republic of Hungary, 
    169 F. Supp. 3d 143
    , 170 n.15 (D.D.C. 2016).
    28
    We therefore affirm the district court’s denial of the Rule
    12(b)(7) motion to dismiss for failure to join a necessary party.
    IV.
    Defendants further seek our review of the district court’s
    denial of the Rule 12(b)(6) motion to dismiss for failure to
    exhaust potential remedies in Hungary, arguing that principles
    of international comity require prudential exhaustion. In Simon
    and Philipp, we held that cases against foreign states under the
    FSIA are not subject to a prudential exhaustion requirement.
    Simon v. Republic of Hungary, 
    911 F.3d 1172
    , 1180–82 (D.C.
    Cir. 2018); Philipp v. Federal Republic of Germany, 
    894 F.3d 406
    , 416 (D.C. Cir. 2018). The district court thus correctly
    determined that, at the time of its decision, “[b]inding Circuit
    precedent foreclose[d] defendants’ argument that prudential
    exhaustion bar[red] plaintiffs’ claims.” Remand II, 
    2020 WL 2343405
    , at *33 (first citing Simon, 911 F.3d at 1181; and then
    citing Philipp, 894 F.3d at 415). The Supreme Court has since
    vacated both of those decisions on other grounds. Federal
    Republic of Germany v. Philipp, 
    141 S. Ct. 703
     (2021);
    Republic of Hungary v. Simon, 
    141 S. Ct. 691
     (2021) (per
    curiam). As a formal matter, that vacatur reopens the issue in
    this circuit. Because requiring exhaustion would result in the
    dismissal of the suit, we deem it appropriate to address this
    issue now. See 
    28 U.S.C. § 1292
    (b).
    We reaffirm our holdings and rationales in Simon and
    Philipp that the FSIA does not require prudential exhaustion in
    suits against foreign states. The FSIA “replac[ed] the old
    executive-driven, factor-intensive, loosely common-law-based
    immunity regime” with a “‘comprehensive set of legal
    standards governing claims of immunity in every civil action
    against a foreign state.’” Republic of Argentina v. NML
    Capital, Ltd., 
    573 U.S. 134
    , 141 (2014) (quoting Verlinden
    29
    B.V. v. Central Bank of Nigeria, 
    461 U.S. 480
    , 488 (1983)).
    “Thus, any sort of immunity defense made by a foreign
    sovereign in an American court must stand on the Act’s text.
    Or it must fall.” 
    Id.
     at 141–42. In particular, “[w]hen Congress
    wanted to require the pursuit of foreign remedies as a predicate
    to FSIA jurisdiction, it said so explicitly.” Simon, 911 F.3d at
    1181; accord Philipp, 894 F.3d at 415. The terrorism
    exception, for example, requires a claimant to first “afford[] the
    foreign state a reasonable opportunity to arbitrate the claim.”
    28 U.S.C. § 1605A(a)(2)(A)(iii); see also id. § 1350 note § 2(b)
    (Under the Torture Victim Protection Act, “[a] court shall
    decline to hear a claim under this section if the claimant has not
    exhausted adequate and available remedies in the place in
    which the conduct giving rise to the claim occurred.”). The
    FSIA expropriation exception contains no such exhaustion
    requirement. See id. § 1605(a)(3). It is not our place to add one.
    We therefore affirm the district court’s denial of the motion to
    dismiss based on prudential exhaustion.
    V.
    Both the Defendants and the family also ask us to review
    now the district court’s determinations asserting or declining
    jurisdiction over specific artworks. We need not review those
    fact-bound determinations on this interlocutory appeal. None
    “involves a controlling question of law as to which there
    is substantial ground for difference of opinion” such that
    immediate appellate review will “materially advance the
    ultimate termination of the litigation.” 
    28 U.S.C. § 1292
    (b).
    VI.
    For the foregoing reasons, we grant the petition for
    permission to appeal as to the district court’s determinations
    that the suit may proceed under Rule 19, that the family may
    30
    amend its complaint to add MNV as a defendant, and that
    prudential exhaustion is not required; we deny the petition and
    conditional cross-petition for permission to appeal as to the
    district court’s determinations of jurisdiction over individual
    artworks. We affirm the district court on each of the issues
    appealed.
    So ordered.