Drumgold v. Callahan , 707 F.3d 28 ( 2013 )


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  •            United States Court of Appeals
    For the First Circuit
    Nos. 11-1304, 11-2016, 12-1052
    SHAWN DRUMGOLD,
    Plaintiff, Appellee,
    v.
    TIMOTHY CALLAHAN,
    Defendant, Appellant,
    FRANCIS M. ROACHE; PAUL MURPHY;
    PATRICIA A. MURPHY, as Executrix of the Estate of Paul Murphy;
    RICHARD WALSH; CITY OF BOSTON,
    Defendants.
    APPEALS FROM THE UNITED STATES DISTRICT COURT
    FOR THE DISTRICT OF MASSACHUSETTS
    [Hon. Nancy Gertner, U.S. District Judge]
    Before
    Lynch, Chief Judge,
    Lipez and Thompson, Circuit Judges.
    Joseph L. Tehan, Jr., with whom Jackie Cowin, Gregg J. Corbo,
    and Janelle M. Austin were on brief, for appellant.
    Michael W. Reilly, with whom Rosemary Curran Scapicchio was on
    brief, for appellee.
    January 31, 2013
    LIPEZ,    Circuit   Judge.     In    the   summer   of   1988,
    twelve-year-old Darlene Tiffany Moore was killed by a stray bullet
    during a gang-related shooting in Boston. Appellant Shawn Drumgold
    was tried and convicted of Moore's murder in Massachusetts state
    court in the fall of 1989.        After serving fourteen years of his
    life sentence, Drumgold moved for a new trial on the ground that
    exculpatory evidence had been withheld by several Boston police
    officers involved in his prosecution, including appellee Timothy
    Callahan, a homicide detective. Drumgold's motion was granted, the
    district attorney's office declined to prosecute him again, and he
    was released from prison in 2003.
    Shortly after his release, Drumgold filed a civil action
    in federal district court pursuant to 
    42 U.S.C. § 1983
     against
    Callahan,    Boston   police    commissioner    Francis   Roache,    police
    officers Paul Murphy and Richard Walsh, and the City of Boston.
    Drumgold alleged that his constitutional due process rights were
    violated by the withholding of material exculpatory evidence during
    his criminal trial, in contravention of Brady v. Maryland, 
    373 U.S. 83
     (1963).    In 2008, a jury determined that Callahan had withheld
    some evidence but deadlocked on whether his failure to disclose
    that evidence had caused Drumgold's conviction.1          As a result, a
    1
    Drumgold's claims against Murphy were dismissed prior to
    trial. The claims against Roache and the City of Boston remain
    pending in the district court. The claims against Walsh went to
    trial together with those against Callahan, but the jury found that
    Walsh was not liable. Only Drumgold's claims against Callahan are
    -2-
    mistrial was declared and a retrial held in 2009.            The retrial jury
    also found that Callahan had withheld evidence and determined that
    his actions had caused Drumgold's conviction. Drumgold was awarded
    damages of $14 million -- $1 million for each year he spent in
    prison.
    On   appeal,   Callahan    argues   that   he   is    entitled   to
    judgment as a matter of law on three different grounds, namely,
    that the withheld evidence is not material within the meaning of
    Brady, that he is entitled to qualified immunity for his actions,
    and that the scope of the retrial was too broad.                  After careful
    consideration, we reject these arguments.           However, we agree with
    Callahan's alternative claim that he is entitled to a new trial
    because the district court judge erred in instructing the retrial
    jury on causation.          Accordingly, we remand this case to the
    district court for a new trial.
    I.
    A.    The 1989 Criminal Trial
    On August 19, 1988, Moore was shot and killed by two
    masked men while sitting on a mailbox in front of her mother's home
    in Boston.    Ten days later, city police officers arrested Drumgold
    and    his   friend   Terrance    Taylor.        They   were      charged   with
    first-degree murder and brought to trial in Massachusetts state
    court in the fall of 1989.       Phil Beauchesne, an assistant district
    relevant for the purposes of this appeal.
    -3-
    attorney, led their prosecution.              The prosecution's theory of the
    case, laid out in Beauchesne's opening statement, was that the
    bullet that killed Moore was intended for Chris Chaney, a gang
    member       who    was    standing    nearby.    Chaney     was   thought   to   be
    responsible, along with a man named Mervin Reese, for the shooting
    of Romero Holliday, a rival gang member whom the prosecution
    believed to be an associate of Drumgold's.
    At trial, Beauchesne called a series of witnesses who
    tied Drumgold, and in some instances Taylor, to Moore's murder.
    One of these witnesses (and the focus of this appeal) was Ricky
    Evans.2      Evans testified that he saw Drumgold and Taylor carrying
    guns shortly before Moore was killed, about two blocks from the
    murder scene.             According to Evans, Taylor told Drumgold at that
    time       that    he   knew   where   they   could   find   Chaney   and    Reese,
    Holliday's supposed assailants.               The next time Evans encountered
    Drumgold and Taylor, approximately an hour after the shooting, they
    were no longer armed and Drumgold appeared nervous.                   Evans heard
    Taylor say that their guns were "hot" and had been "stashed" in a
    safe location.
    Evans was impeached with his past criminal activity and
    other bad acts, as well as with evidence that police officers
    investigating Moore's murder helped him clear up some outstanding
    2
    We summarize the testimony of other prosecution witnesses
    below.
    -4-
    warrants.    Taylor's counsel also noted that it took Evans ten
    months to come forward with information regarding Moore's death and
    probed his motivation for testifying.        Evans explained that he
    "didn't want to get involved" at first but later changed his mind:
    "I just felt like [Moore's mother] lost her daughter so why not go
    and tell the truth when you can. . . . I got a daughter myself and
    I wouldn't want her to be sitting on the mailbox and get shot."
    After the prosecution rested, the state court dismissed
    the charges against Taylor, finding insufficient evidence to permit
    a reasonable jury to convict him.      Drumgold then testified in his
    own defense, denying any part in Moore's death.     Drumgold offered
    an alibi, corroborated by his friend Paul Durand as well as by
    Taylor, that he was drinking wine coolers with Durand outside
    Taylor's girlfriend's house at the time of the shooting and only
    later ended up near the murder scene, which was half a block from
    where his girlfriend and daughter lived.     Drumgold also presented
    third-party culprit evidence suggesting that Moore was killed by
    two prominent members of Holliday's gang, Theron Davis and London
    Williams, in a failed attempt to take revenge on Chaney for the
    attack on Holliday, as well as for an incident in which Chaney
    stabbed Davis in the hand a month before Moore's death.     There was
    a stipulation at trial that, on the day of Moore's murder, a car
    dealership loaned Williams a white Suzuki jeep -- the exact type of
    vehicle that witnesses said the shooters were driving. One witness
    -5-
    testified that Davis and Williams drove past Chaney in the same
    type of vehicle half an hour before Moore was shot, calling out
    from the car, "we'll be back."             A few hours later, Davis was
    stopped in a white Suzuki jeep by a Boston police officer.
    Once Drumgold concluded his defense, the charges against
    him went to the jury, which returned a guilty verdict on October
    13, 1989, after deliberating less than one full day.           Drumgold was
    sentenced to life in prison.
    B.   The 2008 Civil Trial
    In 2003, fourteen years after his conviction, Drumgold
    moved for a new trial in Massachusetts state court on the basis
    that exculpatory evidence casting doubt on the testimony of several
    prosecution witnesses was not disclosed to him during his 1989
    criminal trial. Drumgold's motion was granted, and he was released
    from prison after the district attorney's office entered a nolle
    prosequi,   indicating   that   it   was    abandoning   his   prosecution.
    Drumgold then filed a civil suit in federal district court under 
    42 U.S.C. § 1983
    , alleging, as relevant to this appeal, that Callahan
    violated his constitutional due process rights by withholding
    evidence that would have discredited Ricky Evans.3               Drumgold's
    civil claims against Callahan went to trial in the spring of 2008.
    3
    Drumgold also alleged that Callahan withheld evidence
    regarding two other prosecution witnesses, Mary Alexander and Tracy
    Peaks. Those allegations were rejected by the jury in the 2008
    civil trial and are not pertinent to this appeal.
    -6-
    At the civil trial, Evans testified on Drumgold's behalf
    that he had perjured himself during the 1989 criminal trial in
    order to please Callahan.4    Evans explained that he first met
    Callahan in December 1988, when Callahan was investigating the
    execution-style murder of Evans's cousin by a person named Treas
    Carter ("the Treas Carter case").       By the time Callahan was
    assigned to Drumgold's case, about six months later, the two men
    had become "close like friends."     Evans had also learned that he
    could profit by aiding Callahan's investigations: "[I]t was like if
    I told him what he wanted to hear, I could get what I wanted, and
    I started getting what I wanted so I started giving him what he
    wanted to hear."
    During one conversation about the Treas Carter case,
    Callahan asked Evans if he had any information regarding Moore's
    death.   When Evans indicated that he did, Callahan produced a
    picture of Drumgold and said, "[t]his is the guy here."   According
    to Evans, there was no convincing Callahan that Drumgold was not
    the culprit:
    I knew it wasn't Shawn that had did the
    shooting that night, you know, because
    everybody in the neighborhood said it was
    [Theron Davis].   But it was like [Callahan]
    wouldn't take, you know, "no" for an answer
    that it was not Shawn. You know, he wouldn't
    take it. Like, after, you know, when I tell
    4
    There is no indication in the record that Evans was ever
    criminally charged with perjury.
    -7-
    him [Davis] did it, it was like I was just
    pointing at a blank picture.
    Some time after this initial discussion -- Evans could
    not remember exactly when, except that it was on "a summer night"
    in 1989 -- Callahan arranged for Evans, who was homeless, to stay
    at a Howard Johnson hotel in Boston.   Evans claimed that, during
    the lead-up to Drumgold's criminal trial, he and Callahan met on
    several occasions at the hotel restaurant, where Callahan prepared
    him to testify for the prosecution by feeding him facts that
    implicated Drumgold in the shooting.    In the eight months that
    Evans recalled boarding at the hotel, he never paid a bill, he was
    permitted to come and go as he liked, and he was able to charge
    meals at the hotel restaurant to his room.     No one monitored his
    visitors or kept track of his whereabouts.      In addition, Evans
    testified that, while he was at the hotel, Callahan provided him
    with money upon request: "If I needed, like, say if I needed money
    or something, I would just give him a call, I'd call him, and, you
    know, he'd like, drop me off $30, $40, $50."
    These benefits were of great value to Evans in his
    impoverished state:
    I was living in a hotel I could bring anybody
    that I wanted to, I mean, I could feed them,
    my whole family. It was a big deal to me. I
    was moved off the street into a hotel.      I
    didn't have to worry about nothing. I needed
    money, I gave them a call . . . . I didn't
    have anything to worry about, take me off the
    street and put me in like a five star. See, I
    was wearing the same clothes every day that
    -8-
    week, then I get Detective Callahan . . . I
    didn't have to worry about it no more, so I
    told them what they wanted to hear.
    None of these benefits were disclosed to Drumgold prior to or
    during his criminal trial.
    Callahan disputed the main thrust of Evans's testimony.
    He denied feeding Evans any information about Moore's murder or
    inducing Evans to testify in any particular fashion during the 1989
    criminal trial.      Callahan testified that he placed Evans in the
    hotel only a few weeks before the criminal trial -- on September
    12, 1989 -- and that he did so out of concern for Evans's safety as
    a cooperating witness in Drumgold's case, as well as in the Treas
    Carter case.   He also said that he only gave Evans money ($20) on
    one occasion, because Evans was hungry and had no means to purchase
    food.   Callahan acknowledged that there was no contemporaneous
    written documentation of either benefit, although he was "sure" he
    reported to Beauchesne that he had "placed [Evans] in a hotel."      He
    also recalled disclosing Evans's accommodations to the prosecutor
    assigned to the Treas Carter case, Paul Connolly, who worked down
    the hall from Beauchesne.     A January 1990 memorandum to a witness
    advocate from Connolly stated: "[Y]ou will remember that our
    witness Ricky Evans was in need of housing" and "we had in effect
    relocated   him to    a hotel."   However,   neither   Beauchesne   nor
    Connolly had any memory of discussing Evans's hotel accommodations
    with Callahan.
    -9-
    To help the jury understand the role Evans played in the
    1989 criminal trial, transcripts of that proceeding were read aloud
    during the 2008 civil trial and admitted into evidence as exhibits.
    Against this backdrop, the district judge sent the case to the jury
    in two phases.     In the first phase, the jury was directed to
    complete a special verdict form that, in pertinent part, included
    the following two questions:
    (1) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that
    Defendant Timothy Callahan violated his right
    to a fair trial by withholding exculpatory
    evidence   from  prosecutors,   manufacturing
    evidence, and/or obtaining false statements
    regarding Ricky Evans being housed at a hotel
    and provided with meals?
    (2) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that
    Defendant Timothy Callahan violated his right
    to a fair trial by withholding exculpatory
    evidence   from   prosecutors,  manufacturing
    evidence, and/or obtaining false statements
    regarding Ricky Evans being given substantial
    amounts of money?
    The jury answered "no" to the first question and "yes" to the
    second.      Apprehending   the    inherent    ambiguity   in   the   phrase
    "substantial amounts of money," the district judge proposed to ask
    the jury to clarify its response to the second question. When both
    parties objected, the judge did not seek the clarification.
    Proceeding to the second phase, the judge instructed the
    jury   to   consider   whether    Callahan's   withholding      of   evidence
    concerning the provision of money to Evans had caused Drumgold's
    -10-
    conviction and, if so, the amount of damages due to Drumgold.               The
    parties   presented     additional    evidence     and   delivered    closing
    arguments    as   to   causation   and      damages.     After   a   week   of
    deliberations, the jury reported that it could not agree on the
    causation question, and the judge declared a mistrial.
    Immediately following the declaration of a mistrial,
    Callahan requested the entry of a final judgment on all issues
    decided by the jury in his favor.           The judge said that Callahan's
    request seemed appropriate:
    Entry of judgment would make sense with
    respect to . . . the issues that were finally
    decided by the jury on Officer Callahan. . . .
    In other words, when the jury said no
    liability for Officer Callahan with respect to
    . . . all aspects of Ricky Evans except for
    the money, that judgment it seems to me, can
    enter.
    She then addressed the scope of a possible retrial:
    If there would be a retrial . . . I'm not sure
    that it would be possible to separate out as a
    matter of fact the issues about the hotel, et
    cetera, from the issues of money so that a
    retrial on Officer Callahan I think would
    cover the entire story, but the only question
    that that jury would be asked is about the
    money.
    The judge elaborated:
    [E]ven the finding of liability for Officer
    Callahan on the money would . . . be up in the
    air because the jury -- that wasn't a complete
    verdict, there had to have been a verdict of
    that finding plus proximate cause, so that's
    not a complete verdict, and judgment should
    not be entered one way or the other with
    respect to that.
    -11-
    However, when it later became clear that a retrial would
    take place, the judge declined to enter judgment in Callahan's
    favor on any issues relating to Evans that were decided in the 2008
    trial.    She ruled that the retrial would not be limited to the
    causation question on which the first jury hung, but also would
    revisit   the    antecedent   question      of   whether   Callahan   withheld
    evidence that he gave Evans money, as well as the question of
    whether he withheld evidence that he housed Evans at a hotel.
    C.   The 2009 Retrial
    The retrial was held in September 2009.            Much of the
    evidence mirrored the evidence in the 2008 civil trial, including
    transcripts from the 1989 criminal trial. Evans repeated his prior
    testimony that he perjured himself during the criminal trial in
    order    to   curry   favor   with   Callahan,     that    Callahan   fed   him
    information     implicating   Drumgold      in   Moore's   murder,    and   that
    Callahan housed him for eight months at a Howard Johnson hotel and
    gave him money "whenever [he] needed it."              Evans also testified
    that he informed Callahan that "everybody in the neighborhood"
    believed Theron Davis had killed Moore, but Callahan was "possessed
    with Shawn Drumgold": "[T]he only person that he wanted to hear
    about was Mr. Drumgold.        He didn't want . . . to hear anything
    about [Davis], he wanted to finger Shawn."
    Callahan again denied having fed Evans any information or
    provided any inducements to him. He testified that he placed Evans
    -12-
    in the hotel only a few weeks before the criminal trial and that he
    did   so   in   order   to    "guarantee   not   only   his   safety   but   his
    attendance before the court."           Callahan also testified that he
    disclosed Evans's accommodations to Beauchesne and to Connolly,
    although he did not document that benefit in a written report.                He
    added that the only occasion on which he gave Evans money (again,
    $20) was when he first took Evans to the hotel, because Evans had
    not eaten that day.          The attorney who had represented Drumgold at
    his criminal trial testified that, even if he had known Callahan
    gave Evans $20 for food, "that . . . probably would not have been
    an area that [he] would have gone into" in cross-examining Evans.
    The judge again sent the case to the jury in two phases.
    The special verdict form used in the first phase included the
    following questions:
    (1) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that
    Defendant Timothy Callahan intentionally or
    recklessly withheld exculpatory evidence from
    prosecutors regarding Ricky Evans being housed
    at a hotel and provided with meals?
    (2) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that
    Defendant Timothy Callahan intentionally or
    recklessly withheld exculpatory evidence from
    prosecutors regarding money given to Ricky
    Evans?
    -13-
    The jury answered "yes" to both questions.5   As a follow-up to the
    second question, the special verdict form directed the jury to
    determine the amount of money Callahan gave Evans. The two choices
    were "$20" and "more than $20."        The jury marked "$20."    The
    special verdict form then put these questions to the jury:
    (3) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that the
    evidence withheld by Defendant Callahan was
    material?
    (4) Has the Plaintiff, Shawn Drumgold, proven
    by a preponderance of the evidence that the
    evidence withheld by Defendant Callahan was a
    legal cause of Mr. Drumgold's conviction?
    The jury answered "yes" to both questions, finding Callahan to be
    liable. That finding concluded the first phase of the retrial.    In
    the second phase, the jury awarded Drumgold $14 million in damages.
    This appeal followed.        Because there was no "final
    decision" that could be appealed after the 2008 trial, 
    28 U.S.C. § 1291
    ; see also Baetjer v. Garzot Fernandez, 
    329 F.2d 798
    , 799
    (1st Cir. 1964) (per curiam), we discuss Callahan's claim that
    there never should have been a 2009 retrial, as well as his claims
    relating to the 2009 retrial.
    II.
    We first address the three issues that Callahan claims
    would entitle him to judgment as a matter of law.   After rejecting
    5
    The jury was also asked whether Drumgold had proven that
    Callahan intentionally or recklessly obtained false statements or
    manufactured evidence. The jury answered "no" to that question.
    -14-
    Callahan's arguments on these issues, we proceed to his alternative
    assertion that he is entitled to a new trial because the causation
    instruction given to the retrial jury was erroneous.       Since we
    agree with Callahan on that claim, we do not consider his other
    arguments for a new trial or further proceedings.6
    A.   The Materiality of the Withheld Evidence
    Callahan argues that none of the evidence he was found to
    have withheld during Drumgold's criminal trial is material within
    the meaning of Brady.     We provide an overview of Brady before
    turning to the merits of this issue.
    1.   Brady
    Brady was an "extension" of a line of cases beginning
    with Mooney v. Holohan, 
    294 U.S. 103
     (1935), and Pyle v. Kansas,
    
    317 U.S. 213
     (1942), in which the Supreme Court held that a state
    actor violates a criminal defendant's due process rights by the
    knowing use of perjured testimony or the deliberate suppression of
    evidence leading to the defendant's conviction.      
    373 U.S. at 86
    ;
    see also Kyles v. Whitely, 
    514 U.S. 419
    , 432 (1995) (noting that
    Brady "can trace its origins to early 20th-century strictures
    against misrepresentation"). The duty that these cases established
    6
    Callahan's other arguments are that the judge erred in
    excluding from the 2009 retrial a package of forty-five
    investigative reports, instructing the retrial jury on the extent
    of damages for which he could be held liable, failing to remit a
    portion of the damages award, and awarding excessive attorneys'
    fees.
    -15-
    has always applied equally to prosecutors and law enforcement
    officers.    See Haley v. City of Boston, 
    657 F.3d 39
    , 50 (1st Cir.
    2011); Limone v. Condon, 
    372 F.3d 39
    , 47 (1st Cir. 2004).
    Brady broke new ground in holding that a prosecutor also
    violates a defendant's due process rights merely by failing to
    disclose material evidence in his possession that is favorable to
    the defendant, irrespective of the good or bad faith of the
    prosecutor.    See 
    373 U.S. at 87
    .   As a result, Brady is "sometimes
    referred to as imposing a no-fault disclosure obligation" on
    prosecutors.    Haley, 
    657 F.3d at 48
    ; see also Porter v. White, 
    483 F.3d 1294
    , 1305 (11th Cir. 2007) ("The Brady rule . . . imposes a
    no-fault standard of care on the prosecutor.").        Subsequent to
    Brady, the Supreme Court clarified that this affirmative disclosure
    obligation also encompasses evidence known only to law enforcement
    officers and not to prosecutors.      See Kyles, 
    514 U.S. at 437-38
    ;
    see also Strickler v. Greene, 
    527 U.S. 263
    , 280-81 (1999); Haley,
    
    657 F.3d at 49
    .     Although "the responsibility for obtaining and
    disclosing . . . evidence remains the duty of the prosecutor,"
    Haley, 
    657 F.3d at 49
    , law enforcement officers have a correlative
    duty to turn over to the prosecutor any material evidence that is
    favorable to a defendant, see Moldowan v. City of Warren, 
    578 F.3d 351
    , 381 (6th Cir. 2009); McMillian v. Johnson, 
    88 F.3d 1554
    , 1567
    (11th Cir. 1996).    Evidence is favorable to a defendant if it is
    either exculpatory or impeaching in nature.     See United States v.
    -16-
    Bagley, 
    473 U.S. 667
    , 676 (1985). Evidence is material if there is
    a "reasonable probability" that, had it been disclosed, the result
    of the proceeding would have been different.        
    Id. at 682
    .7     "The
    question is not whether the defendant would more likely than not
    have received a different verdict with the evidence, but whether in
    its absence he received a fair trial, understood as a trial
    resulting in a verdict worthy of confidence."       Kyles, 
    514 U.S. at 434
    . Thus, a reasonable probability exists when the withholding of
    evidence undermines confidence in the outcome of the trial.          See
    id.; Bagley, 
    473 U.S. at 682
    .
    We   have   been   careful    to   distinguish   between    the
    proscription originating in Mooney and Pyle against the deliberate
    suppression of evidence and the more recent affirmative disclosure
    obligation announced in Brady.     See Haley, 
    657 F.3d at 46
    .         The
    allegations in this case primarily go to deliberate suppression.
    However, the record does not permit us to exclude the possibility
    that Callahan merely failed to disclose evidence with a less
    culpable state of mind, particularly in light of the retrial jury's
    7
    "Significant possibility" might be a better term than
    "reasonable probability" because the latter term "raises an
    unjustifiable risk of misleading courts into treating it as akin to
    the more demanding standard, 'more likely than not.'" Strickler,
    
    527 U.S. at 298
     (Souter, J., concurring in part and dissenting in
    part). Nevertheless, "reasonable probability" remains the proper
    formulation.
    -17-
    finding that he acted "intentionally or recklessly."8 We therefore
    construe Drumgold's invocation of Brady as shorthand for his full
    complement of due process rights, including both those articulated
    in Mooney and Pyle and those first described in Brady itself.      See
    Strickler, 
    527 U.S. at 281-82
     (explaining that "a true Brady
    violation" involves evidence that was "suppressed by the State,
    either willfully or inadvertently").
    2.   Analysis
    With this framework in mind, we focus on the merits of
    the materiality issue, beginning with the 2008 civil trial and then
    moving to the 2009 retrial.       There are serious questions as to
    whether Callahan properly preserved this issue for our review in
    either proceeding.      If the issue was preserved, our review is de
    novo.     See Zachar v. Lee, 
    363 F.3d 70
    , 73 (1st Cir. 2004).   If not,
    our review is for plain error.     See Simon v. Navon, 
    71 F.3d 9
    , 13
    (1st Cir. 1995). However, since Callahan's challenge fails even if
    we apply the standard of review most favorable to him, we will
    assume the issue is preserved and review de novo whether he is
    entitled to judgment as a matter of law.      See Zachar, 
    363 F.3d at 73
    .     "In undertaking this review, we look to all evidence in the
    8
    The district judge at one point instructed the retrial jury
    that it could hold Callahan liable only if it found that he
    "knowingly and deliberately" withheld evidence, but she also
    repeatedly explained that Drumgold had to prove that Callahan acted
    "intentionally or recklessly," and the special verdict form used in
    the retrial reflected that formulation.
    -18-
    record, drawing all reasonable inferences therefrom in [Drumgold's]
    favor, and resist the temptation to weigh the evidence or make our
    own credibility determinations."      
    Id.
       We may rule in Callahan's
    favor only if no reasonable person could view the withheld evidence
    as material. See id.; Correa v. Hosp. San Francisco, 
    69 F.3d 1184
    ,
    1191 (1st Cir. 1995).
    a.     The 2008 Trial
    To recap, the jury in the 2008 trial found that Callahan
    withheld evidence that he provided Evans with "substantial amounts
    of money."   The question is whether a reasonable jury could view
    that evidence as material.
    Evans was one of the prosecution's star witnesses during
    Drumgold's criminal trial.      As described above, he testified that,
    shortly before   Moore    was   killed,   he saw   Drumgold   and   Taylor
    carrying guns near the murder scene. He also testified that Taylor
    told Drumgold at that time that he knew where they could find Chris
    Chaney and Mervin Reese, whom Beauchesne identified in his opening
    statement as the intended targets of Moore's shooting.          Finally,
    Evans testified that when he next encountered the pair, about an
    hour after the shooting, Drumgold appeared anxious and Evans heard
    Taylor say that their guns were "hot" and had been "stashed" in a
    safe location.
    To be sure, other witnesses also linked Drumgold to
    Moore's death. Chris Cousins testified that he visited the wounded
    -19-
    Romero Holliday in the hospital shortly before Moore was killed.
    There, Cousins heard Holliday tell Drumgold and Taylor that Chaney
    and Reese had shot him, prompting Drumgold and Taylor to assure
    Holliday that they were "going to get who did it" in retaliation.
    Another       witness,   Vantrell    McPherson,   testified   that   she    saw
    Drumgold and Taylor two streets away from where Moore was shot
    approximately three hours before the shooting, and that Taylor had
    said to Drumgold, "[c]ome on, Shawn, you know we got to go do
    this," although McPherson had not known what the two men were
    talking about.
    Two witnesses claimed to have seen Drumgold near the
    scene    of    Moore's   shooting    shortly   after   it   occurred.      Mary
    Alexander, who lived a few blocks away, testified that she heard a
    gunshot and then saw a man whom she identified in court as Drumgold
    climb over a fence behind her house with a gun tucked into his
    waistband.       Tracy Peaks, a neighbor of Alexander's, testified that
    a man she recognized as Drumgold walked casually by her home just
    after Moore was killed.        A third witness, Eric Johnson -- who had
    been leaning on the mailbox where Moore was perched and who "kn[e]w
    [Drumgold] from the neighborhood" -- testified that he suspected
    one of the masked shooters was Drumgold, largely because one
    shooter appeared "bowlegged," as Johnson believed Drumgold to be.
    However, the testimony of many of these witnesses was
    called    into    serious   doubt.     On    cross-examination,   Drumgold's
    -20-
    attorney elicited from Alexander the admissions that she had not
    initially been able to pick out Drumgold from a photo array after
    the shooting and that, before identifying him in court, she had
    seen Drumgold's picture in a Boston newspaper alongside an article
    describing him as Moore's killer. In addition, Alexander said that
    Drumgold appeared to be significantly shorter than the man whom she
    saw climb a fence behind her house.       Drumgold's attorney also got
    Johnson to concede that he was not certain the bowlegged shooter
    was Drumgold: "I'm not going to say it was Shawn. . . .        I say he
    looked similar to Shawn.    I can't come out and say straight it was
    Shawn.   I don't know."       Romero Holliday testified that Chris
    Cousins never visited him in the hospital, where Cousins claimed to
    have overheard Drumgold and Taylor promise to "get" whomever had
    shot Holliday.   In fact, Holliday claimed that he did not even know
    Drumgold at the time of Moore's murder.
    Evans's   testimony,   too,   was   impeached.   There   was
    evidence at trial of his past criminal activity and other bad acts,
    as well as evidence that police officers investigating Moore's
    death assisted him with outstanding warrants.          Taylor's counsel
    also questioned why Evans did not come forward with information
    until ten months after the shooting.       The existence of this other
    impeachment evidence is relevant to the claim here insofar as it
    offered a reason to disbelieve Evans even without the withheld
    evidence.   See United States v. Brandao, 
    539 F.3d 44
    , 64 (1st Cir.
    -21-
    2008); Mastracchio v. Vose, 
    274 F.3d 590
    , 603 (1st Cir. 2001).
    Still, its impact at trial was countered by Evans's insistence that
    his motivation for testifying was sympathy for Moore's mother: "I
    just felt like she lost her daughter so why not go and tell the
    truth when you can. . . . I got a daughter myself and I wouldn't
    want her to be sitting on the mailbox and get shot." Evidence that
    Callahan gave Evans "substantial amounts of money" for assisting
    with the investigation and prosecution of Drumgold could have put
    the lie to that claim.
    The record is mixed as to when Evans received the money
    in question.   By all accounts, it was while he was living at the
    Howard Johnson hotel.    Evans was unable to recall the exact date
    that he moved into the hotel, except that it was on "a summer
    night" in 1989.    He also could not recollect when he left the
    hotel, although it was some time after Drumgold's criminal trial
    concluded.   In all, Evans estimated that he lived at the hotel for
    eight months. According to Callahan, however, Evans arrived at the
    hotel only a few weeks before the criminal trial -- on September
    12, 1989. This chronology is important because, as Callahan points
    out, Evans's criminal trial testimony was consistent with pretrial
    statements he made as early as June 21, 1989.   If these statements
    preceded Evans's receipt of money from Callahan, disclosure of that
    benefit might have made a smaller splash at the criminal trial.
    See Mastracchio, 
    274 F.3d at 603-04
    .
    -22-
    Although it is hardly conclusive, there was sufficient
    evidence in the 2008 trial -- drawing all reasonable inferences
    from the record in Drumgold's favor, see Zachar, 
    363 F.3d at
    73 --
    that Evans was already living in the Howard Johnson hotel at the
    time of his pretrial statements.       Drumgold's criminal trial ended
    on October 13, 1989.    Given Evans's testimony that he departed the
    hotel some time afterward, and his estimation that he boarded at
    the hotel for eight months in total, he could have arrived there
    before June 21, 1989, and so he could have been receiving cash
    assistance from Callahan before he gave pretrial statements to him.
    This timeline is compatible with Evans's memory of moving into the
    hotel on "a summer night."9
    As a result, there is a reasonable probability that, if
    Callahan's provision of "substantial amounts of money" to Evans had
    been disclosed during the 1989 criminal trial, the result of that
    proceeding would have been different.         This is not to say that
    Evans's criminal trial testimony was, on its own, sufficient to
    support Drumgold's conviction.           After all, his testimony was
    equally   inculpatory   of   Taylor,   against   whom   the   state   court
    dismissed all charges. Nevertheless, Evans's testimony was crucial
    in connecting the accounts of other prosecution witnesses against
    Drumgold, and evidence that he received a significant financial
    9
    Although the official first day of summer usually falls on
    June 21, we understand Evans to mean that he moved into the hotel
    on a warm, summer-like evening.
    -23-
    benefit    from   Callahan    might    well   have    affected   the    jury's
    perception of his credibility.
    b.    The 2009 Retrial
    The foregoing analysis applies equally to the retrial
    jury's    determination    that   Callahan    withheld    evidence     that   he
    provided Evans with free lodging.             We have no doubt that a
    reasonable jury could view the lodging evidence as material, the
    same as evidence that Callahan gave Evans "substantial amounts of
    money."    Those benefits were a "big deal" to Evans and transformed
    his quality of life.         There is a reasonable probability that
    disclosure of the lodging benefits would have changed the outcome
    of Drumgold's criminal trial.
    Disclosure of evidence that Callahan gave Evans $20 to
    purchase food on one occasion would not have had the same effect,
    however.    That sum is too small to have made a difference in the
    particular circumstances of this case.               Indeed, the lawyer who
    represented Drumgold during his criminal trial conceded in the 2009
    retrial that he would not have cross-examined Evans about a gift of
    $20. As a result, no reasonable jury could regard this evidence as
    material.
    B.   Qualified Immunity
    Callahan argues that, even if the evidence he withheld
    was material, he is entitled to judgment as a matter of law on the
    basis of qualified immunity because it was not clearly established
    -24-
    at   the   time   of   Drumgold's   criminal     trial   that     he   had   any
    affirmative disclosure obligation under Brady.               Again, there are
    serious questions about whether Callahan preserved this issue for
    our review.       However, because Callahan's argument fails in any
    event, we will once more assume the issue is preserved and apply a
    de novo standard of review.      See Walden v. City of Providence, 
    596 F.3d 38
    , 52 (1st Cir. 2010); Guillemard-Ginorio v. Contreras-Gómez,
    
    585 F.3d 508
    , 525-26 (1st Cir. 2009).           Throughout, we discuss the
    2008 trial and the 2009 retrial together.
    1.    The Qualified Immunity Doctrine
    "Qualified immunity is a judge-made doctrine designed to
    'balance two      important   interests    --   the   need   to   hold   public
    officials accountable when they exercise power irresponsibly and
    the need to shield officials from harassment, distraction, and
    liability when they perform their duties reasonably.'"             Haley, 
    657 F.3d at 47
     (quoting Pearson v. Callahan, 
    555 U.S. 223
    , 231 (2009)
    (internal brackets omitted)).         The doctrine thus protects from
    liability for civil damages all public officials other than those
    who, "from an objective standpoint, should have known that their
    conduct was unlawful." 
    Id.
     (internal quotation marks omitted); see
    also Harlow v. Fitzgerald, 
    457 U.S. 800
    , 818 (1982).
    The qualified immunity inquiry has two parts.                    See
    Pearson, 
    555 U.S. at 232
    ; Maldonado v. Fontanes, 
    568 F.3d 263
    , 269
    (1st Cir. 2009).       A court must decide whether the plaintiff has
    -25-
    made out a violation of a constitutional right and, if so, whether
    the right was clearly established at the time of the violation.
    See Maldonado, 
    568 F.3d at 269
    .         This second part, in turn, has two
    aspects.    See 
    id.
        The first focuses on the clarity of the law at
    the time of the violation.         See 
    id.
         The other aspect focuses more
    concretely on the facts of the particular case and whether a
    reasonable    defendant      would    have    understood   that    his   conduct
    violated the plaintiff's constitutional rights.                   See 
    id.
         The
    "salient question" is whether the state of the law at the time of
    the violation gave the defendant fair warning that his particular
    conduct was unconstitutional. 
    Id.
     (citing Hope v. Pelzer, 
    536 U.S. 730
    , 741 (2002)).
    2.    Application
    We have already rejected Callahan's argument that the
    exculpatory evidence he withheld is not material within the meaning
    of Brady.    It follows that Drumgold has made out a violation of his
    constitutional due process rights.            See Brady, 
    373 U.S. at 87
    .      The
    question we now confront is whether those rights were clearly
    established at the time of the 1989 criminal trial.
    The    essence    of     Callahan's     argument      is   that   the
    affirmative disclosure obligation Brady imposed on prosecutors in
    1963 was not expanded to include law enforcement officers until
    Kyles was decided in 1995.           That is true, so far as it goes.         See
    Haley, 
    657 F.3d at 48-49
    .       As we have said, though, this case also
    -26-
    involves the deliberate suppression aspect of Brady.   There can be
    no doubt that, under the line of cases running from Mooney and Pyle
    to Brady, the law was firmly settled at the time of Drumgold's
    criminal trial that a law enforcement officer may not deliberately
    suppress material evidence that is favorable to a defendant.   See
    
    id. at 49-51
    ; Limone, 
    372 F.3d at 45
    ; Newsome v. McCabe, 
    256 F.3d 747
    , 752-53 (7th Cir. 2001); McMillian v. Johnson, 
    88 F.3d 1554
    ,
    1568-69 (11th Cir. 1996).
    Moreover, to the extent that Callahan acted deliberately,
    a reasonable officer in his position plainly would have appreciated
    the wrongfulness of his conduct. Callahan claims that a reasonable
    officer would not have recognized the evidence in question as
    material because Drumgold's lawyer had not bothered to cross-
    examine another prosecution witness, Travis Johnson, on the fact
    that the district attorney's office paid for his accommodations
    during the criminal trial.    However, Johnson had to travel to
    Boston from another state to testify, and the benefits he received
    were tailored to facilitate his appearance at the trial.        By
    contrast, viewed in the light most favorable to Drumgold, see
    Walden, 596 F.3d at 52, the benefits Evans received had little to
    do with ensuring his availability to testify or, for that matter,
    his safety as a cooperating witness. Evans was permitted to remain
    in the Howard Johnson hotel for eight months, he was free to come
    and go as he pleased, and no one monitored his whereabouts.      A
    -27-
    reasonable officer would have discerned the difference between the
    open-ended    benefits   Evans   received   and   the   far   more   limited
    benefits Johnson received.       As a result, there is no basis for
    awarding Callahan judgment as a matter of law on qualified immunity
    grounds.10
    The dissent's lengthy discussion attempting to show that
    Callahan is entitled to qualified immunity is flawed both factually
    and legally.      As a threshold matter, the dissent argues that
    Drumgold never raised a claim related to the hotel evidence under
    "the Mooney line of cases" and contends that it is unfair to allow
    the belated introduction of such a claim on appeal.                  Although
    Drumgold did not cite Mooney and Pyle by name, the due process
    claim those cases support -- that Callahan deliberately withheld
    10
    We do not mean to suggest that a law enforcement officer can
    be liable today in a damages action under 
    42 U.S.C. § 1983
     only for
    deliberately suppressing evidence.     Non-disclosure with a less
    culpable state of mind might suffice. See Haley, 
    657 F.3d at 47
    (assuming without deciding that "no-fault nondisclosure constitutes
    a viable claim of breach"). This is a difficult question that has
    engendered a range of views. See, e.g., Tennison v. City and Cnty.
    of San Francisco, 
    570 F.3d 1079
    , 1089 (9th Cir. 2009) ("[A] § 1983
    plaintiff must show that police officers acted with deliberate
    indifference to or reckless disregard for an accused's rights or
    for the truth in withholding evidence from prosecutors."); Porter,
    
    483 F.3d at 1306
     ("[T]he no-fault standard of care Brady imposes
    . . . in the criminal or habeas context has no place in a § 1983
    damages action against a law enforcement official in which the
    plaintiff alleges a violation of due process."); Villasana v.
    Wilhoit, 
    368 F.3d 976
    , 980 (8th Cir. 2004) ("[T]he recovery of
    § 1983 damages requires proof that a law enforcement officer . . .
    intended to deprive the defendant of a fair trial."). We do not
    reach this question here. Our holding is limited to the law as it
    was clearly established in 1989, when Callahan engaged in the
    conduct at issue here.
    -28-
    material impeachment evidence -- was a central part of the case as
    tried.     Indeed, in objecting to the district court's proposed jury
    instructions for the 2009 trial, Callahan argued that "the jury
    should     be    explicitly   informed       that    it    is    the    intentional
    suppression -- that is, the intentional withholding of evidence --
    that is the core allegation at issue."              He made similar assertions
    in   his   Memorandum    of   Law   in    Support     of   His    Requested    Jury
    Instructions, where he stated, inter alia, that "[t]he jury should
    . . . be instructed that the burden remains on Drumgold at all
    times to prove intentional and deliberate suppression of evidence
    . . . ."        The suppressed evidence at issue was the provision of
    hotel and cash benefits to Evans, conduct distinct from Drumgold's
    allegation that Callahan had framed him by manufacturing evidence
    and inducing Evans to testify falsely.
    What   matters   is    not   the   nomenclature       of    Drumgold's
    withholding-of-evidence claim -- whether we characterize it as
    "Brady-based" or "Mooney-based" -- but what the parties, the court,
    and the jury understood about the nature of the claim.                          The
    instructions offered by Callahan and given by the court both
    required a finding of intentional or reckless conduct,11 and the
    jury verdict form was likewise framed that way.                 Hence, there is no
    11
    Indeed, the court instructed the jury that "[w]ithholding
    material exculpatory evidence by accident or mistake does not give
    rise to liability under the Federal Civil Rights Act. As I said,
    the conduct must be either intentional or reckless."
    -29-
    lack of notice problem or any other unfairness associated with
    Drumgold's deliberate suppression claim.
    Moreover, the omission of citations to Pyle and Mooney in
    Drumgold's briefing of his Brady claim on appeal does not mean that
    he has discarded the claim that Callahan deliberately suppressed
    evidence. As we have explained, Drumgold's invocation of Brady can
    only reasonably be understood to broadly state the scope of his
    constitutional claim against Callahan, not to limit it to the less
    egregious failure to disclose. It turns the Brady principle on its
    head to say that a constitutional due process claim exists under
    Brady   if    a    police   officer   allegedly    failed   to    fulfill    an
    affirmative obligation to disclose evidence irrespective of fault,
    but not if the officer is alleged to have deliberately suppressed
    that same evidence.         In arguing that Drumgold's "Brady" claim
    covers only the affirmative obligation to disclose evidence -- an
    obligation that was not clearly established for police officers at
    the time of Callahan's alleged actions -- the dissent slices away
    the foundational assumption of Brady that deliberate suppression of
    material evidence is a constitutional violation.               See Strickler,
    
    527 U.S. at 282
     (stating that "a true Brady violation" includes
    instances where evidence was willfully suppressed by the state).
    The    dissent's     confinement     of   Brady     to   no-fault
    nondisclosure claims, while describing a Mooney claim as one of
    "intentional       framing,"    implausibly   leaves   claims    asserting    a
    -30-
    deliberate   withholding     of    evidence     without     a   category   of
    constitutional redress.      To the extent the dissent's labeling is
    only case specific -- that is, the invocation of Brady in this case
    referred only to the affirmative failure to disclose, not the
    deliberate suppression of evidence -- the dissent, as noted, is
    flatly wrong.
    Here, the jury rejected Drumgold's "non-Brady" claim that
    Callahan intentionally framed him by obtaining false statements
    from Evans or otherwise manufacturing evidence.           But it found that
    the exculpatory hotel evidence was "intentionally or recklessly
    withheld" -- conduct that, if deliberate, was clearly unlawful at
    the time Callahan acted.     The labeling of this failure-to-disclose
    claim as a Brady claim, or something else, makes no difference
    where, as a matter of substance, the claim plainly was understood
    by the parties, the judge, and the jury to embrace a culpable state
    of mind.
    The dissent also argues that Callahan would be entitled
    to   qualified   immunity   even   if    the   deliberate   suppression    of
    evidence is covered by Drumgold's Brady claim.              This assertion,
    however, improperly relies on unsupported factual inferences from
    the jury's verdict. The dissent states that the jury's findings do
    not establish specific intent.          We agree -- but that non-finding
    -31-
    does not earn Callahan immunity even assuming that specific intent
    were the only state of mind sufficient to support liability.12
    The special verdict form in the 2009 trial asked whether
    Callahan   "intentionally   or   recklessly    withheld   exculpatory
    evidence," and the jury answered "yes" without specifying the state
    of mind it found.   The dissent points out that the jury "made no
    express finding that Callahan acted with the purpose of suppressing
    such evidence."   Yet the jury also made no express finding that he
    did not.
    Qualified immunity is an affirmative defense.    We see no
    justification for granting immunity based on the supposition that
    the jury found the lesser state of mind, particularly when -- in
    Callahan's words -- "intentional withholding of evidence . . .
    [was] the core allegation at issue."          The dissent points to
    12
    In his Memorandum of Law in Support of His Request for Jury
    Instructions, Callahan stated:
    The jury should be instructed that in order to find
    against Callahan, they must find that his omission of
    material exculpatory evidence must have been essentially
    deliberate. Omission of material exculpatory evidence by
    accident or mistake or through some ordinary level of
    negligence or carelessness does not give rise to
    liability under the statute; rather, the omission must
    have been either intentional or reckless, which the law
    treats as equivalent of intentional.
    Memorandum at 8 (emphasis added); see also, e.g., Tennison, 570
    F.3d at 1088 (stating that a § 1983 plaintiff alleging a due
    process claim against a police officer for withholding evidence
    must show "deliberate indifference to or reckless disregard for an
    accused's rights or for the truth in withholding evidence from
    prosecutors" (emphasis added)).
    -32-
    testimony that Callahan had told a prosecutor not involved in
    Drumgold's case about placing Evans in a hotel and suggests that,
    as a result, the jury could not have found intentional suppression.
    It is the jury's province, however, to weigh such evidence along
    with the other evidence presented at trial concerning Callahan's
    state of mind.    Because another trial is necessary, as we explain
    infra, the jury will again have the opportunity to do so.
    C.    The Scope of the 2009 Retrial
    As noted above, the retrial jury found that Callahan
    withheld evidence that he provided Evans with free housing and $20.
    We have already explained that evidence of the latter benefit is
    not material.     Hence, Callahan cannot be liable for withholding
    that evidence.    Callahan now contends that the retrial jury should
    not have been permitted to reexamine the question of whether he
    withheld the housing evidence, since that question was resolved in
    his favor during the 2008 trial.       He claims that there is, thus, no
    valid basis for his liability and that he is entitled to judgment
    as a matter of law.         There is no dispute that this issue was
    preserved.
    Although much of the relevant background has already been
    laid out elsewhere in this opinion, we repeat portions of it here
    for clarity's sake.     In the 2008 trial, the jury determined that
    Callahan had not withheld evidence that he arranged free housing
    for    Evans,   but   had   withheld   evidence   that   he   gave   Evans
    -33-
    "substantial amounts of money." The jury then hung on the question
    of whether Callahan's misconduct had caused Drumgold's conviction.
    After a mistrial was declared, Callahan moved for the entry of a
    final   judgment   as   to,   inter   alia,   the   housing   issue   and
    simultaneously sought to restrict the scope of a retrial to the
    causation question on which the first jury deadlocked.
    The district judge initially appeared receptive to this
    idea but ultimately rejected it.         She reasoned that a retrial
    limited to causation was not feasible:
    A second jury would obviously have to be
    instructed   that   Callahan    had   violated
    Drumgold's   civil  rights   by   giving   him
    "substantial amounts of money" and not
    disclosing it.   The jury would be left with
    the ambiguity of what "substantial money"
    meant -- an issue wholly unresolved in the
    first trial, notwithstanding the Court's
    efforts to seek further clarification.     And
    the only way to resolve that ambiguity would
    be to relate each side's evidence concerning
    the treatment of Ricky Evans -- why Ricky
    Evans's testimony was significant to the
    Drumgold prosecution, that there had been no
    eyewitnesses to the murder that Drumgold was
    convicted of, . . . the relationship between
    defendant Callahan and the witness, the steps
    that defendant Callahan allegedly took to
    secure Evans's testimony (hotel rooms, meals,
    cash, etc.). In short, all aspects of Ricky
    Evans's portion of this case would be
    involved.
    As a result, the judge declined to enter a final judgment as to the
    housing issue and permitted the retrial jury to determine afresh
    what housing and money benefits, if any, Callahan gave Evans and
    failed to disclose.
    -34-
    The general practice after a mistrial is a full retrial
    of all issues in the case.   See Nissho-Iwai Co. v. Occidental Crude
    Sales, 
    729 F.2d 1530
    , 1538 (5th Cir. 1984).       However, when some
    issues have been properly and conclusively resolved, there may be
    a partial retrial on the remaining issues if it "clearly appears"
    that they are "so distinct and separable from the others that a
    trial of [them] alone may be had without injustice."        Gasoline
    Prods. Co. v. Champlin Refining Co., 
    283 U.S. 494
    , 500 (1931).
    This determination is distinctly within the ken of the trial judge.
    See Sprague v. Boston & Me. Corp., 
    769 F.2d 26
    , 28 (1st Cir. 1985).
    Accordingly, our review of the judge's decision as to the scope of
    the 2009 retrial is for abuse of discretion.    See Winn v. Lafayette
    Town House, 
    839 F.2d 835
    , 837 (1st Cir. 1988); Sprague, 
    769 F.2d at 28
    .
    There were three possible ways to define the scope of the
    retrial.   First, the judge could have confined the retrial to the
    causation inquiry that stymied the first jury.     We agree with the
    judge that this was not a feasible option.     The retrial jury could
    not have conducted a meaningful causation inquiry without rehearing
    the entirety of the 2008 trial evidence involving Evans in order to
    understand both the dynamics of his relationship with Callahan and
    his role in Drumgold's criminal trial. Having heard that evidence,
    the retrial jury inevitably would have drawn its own conclusions as
    to the nature and amount of benefits that Callahan gave Evans, and
    -35-
    would have been confused if prevented from returning a verdict
    reflecting    those   conclusions.      While   juries   are   frequently
    instructed to consider evidence for one purpose and not others, see
    Fed. R. Evid. 105, we share the district judge's concern that such
    an instruction would have posed an unacceptably high risk of
    confusion in this case, see Colonial Leasing of New England, Inc.
    v. Logistics Control Int'l, 
    770 F.2d 479
    , 481 (5th Cir. 1985)
    ("[W]hen the issues subject to retrial are so interwoven with other
    issues in the case that they 'cannot be submitted to the jury
    independently . . . without confusion and uncertainty, which would
    amount to a denial of a fair trial,' then it is proper to grant a
    new trial on all of the issues raised." (quoting Gasoline Prods.,
    
    283 U.S. at 500
    )); Sears v. S. Pac. Co., 
    313 F.2d 498
    , 503 (9th
    Cir. 1963).
    The second route the judge could have taken was to allow
    the retrial jury to revisit whether Callahan withheld evidence that
    he gave money to Evans but not whether Callahan withheld evidence
    regarding the housing benefit.       This approach, too, would have
    risked confusion since the evidence concerning the various benefits
    at issue here overlaps both topically and temporally. Moreover, it
    would have been unfair to Drumgold if he had to prove anew in the
    retrial that Callahan withheld evidence of a financial benefit to
    Evans, but Callahan was able to capitalize on the first jury's
    finding that he did not withhold evidence of a housing benefit.
    -36-
    The   third       option,    which    the    judge    embraced,     was   a
    compromise solution.             Permitting the retrial jury to reopen the
    housing issue clearly disadvantaged Callahan.                   However, reopening
    the financial benefit issue worked to Callahan's advantage since it
    canceled out the first jury's finding that he withheld evidence
    that he gave Evans "substantial amounts of money." That opened the
    door for Callahan to persuade the retrial jury that the amount of
    money in question was only $20 -- a sum we have now said was too
    low to support his liability.
    We find no abuse of discretion in the judge's ruling.
    The causation inquiry unresolved in the 2008 trial was not "so
    distinct and separable" from the housing issue that a partial
    retrial   limited     to     causation     plainly      could    be    had    without
    injustice. Gasoline Prods., 
    283 U.S. at 500
    . The judge's solution
    to that problem was sensible and evenhanded.
    The dissent's contrary view fails to give deference to
    the district court's carefully considered compromise and, hence,
    cannot be reconciled with the abuse of discretion standard.                       This
    is a difficult case, factually and legally. The 2008 trial spanned
    twenty-five days. The district court judge was deeply engaged with
    the   issues   over     a    lengthy    period     of   time.         Our   colleague
    nonetheless    challenges         the   district    court's      judgment     with   a
    scattershot    effort       to    depict its    ruling as       both    legally   and
    factually erroneous.         The dissent's analysis, however, reduces to
    -37-
    a disagreement with the district court on a question that is
    uniquely within the district court's expertise: whether this is a
    case where "the issues were too 'interwoven' to retry one issue
    separately."
    As we have explained, the district court had multiple
    paths to choose from.   Its conclusion that the facts surrounding
    the provision of "substantial amounts of money" to Evans inevitably
    would implicate the entirety of Callahan's relationship with Evans
    is supportable and, in the context of this case, does not require
    the extensive elaboration required by our colleague.    The district
    court's explanation was wholly adequate.     Nor does the district
    court's ruling conflict with Gasoline Products, where the Supreme
    Court considered the propriety of a court's departure from the
    common law rule that an error with respect to one issue results in
    a new trial on all issues.       See 
    283 U.S. at 497
    .   The Supreme
    Court's conclusion that the Seventh Amendment "does not compel a
    new trial of [all issues] even though another and separable issue
    must be tried again," 
    id. at 499
    , does not tilt the constitutional
    balance in favor of a limited retrial.    In sum, we have no reason
    here -- and no license -- to preempt the district court's choice on
    the contours of the new trial.
    Hence, there was a valid basis for Callahan's liability
    in the 2009 retrial.
    -38-
    D.   The Jury Instructions
    We have now established that Callahan is not entitled to
    judgment as a matter of law.             We turn to his alternative argument
    that a new trial is necessary because the judge's instructions on
    causation to the retrial jury were erroneous.                          We begin our
    discussion with the applicable legal framework and then quote the
    pertinent parts of the jury instructions before setting out the
    standard of review and moving to the merits of the issue.
    1.     The Legal Framework
    Drumgold's claims against Callahan were brought under 
    42 U.S.C. § 1983
    , the federal civil rights statute.                         To recover
    damages   under       §    1983,    Drumgold    must   show   more     than    a    Brady
    violation.      See Johnson v. Mahoney, 
    424 F.3d 83
    , 89 (1st Cir.
    2005); see also Rodriguez v. Woodall, 
    189 F. App'x 522
    , 527 (7th
    Cir.   2006)    ("[A]       constitutional       violation,     such    as     a    Brady
    violation, is necessary, but more is needed.").                        He also must
    demonstrate by a preponderance of the evidence a causal link
    between the Brady violation and his conviction.                  See Johnson, 
    424 F.3d at 89
    .
    As     a       general    rule,     "[w]e   employ   common        law   tort
    principles when conducting inquiries into causation under § 1983."
    Sanchez v. Pereira-Castillo, 
    590 F.3d 31
    , 50 (1st Cir. 2009)
    (internal quotation marks omitted); see also Rodríguez-Cirilo v.
    García, 
    115 F.3d 50
    , 52 (1st Cir. 1997) ("The issue of causation of
    -39-
    damages in a section 1983 suit is based on basic notions of tort
    causation."); Maldonado Santiago v. Velázquez García, 
    821 F.2d 822
    ,
    831 (1st Cir. 1987) ("Section 1983 imposes a causation requirement
    similar to that of ordinary tort law.").     There are exceptions to
    this rule, though, and "[c]are must be taken in applying these
    principles to the § 1983 context."    Olsen v. Correiro, 
    189 F.3d 52
    ,
    66 n.16 (1st Cir. 1999); see also Coscia v. Town of Pembroke,
    Mass., 
    659 F.3d 37
    , 40 (1st Cir. 2011); 1 Sheldon H. Nahmod, Civil
    Rights and Civil Liberties Litigation: The Law of Section 1983
    § 3:106 (4th ed. 2011) ("[T]ort law purposes and interests are
    often different from § 1983 purposes and interests, and thus tort
    law concepts should not be blindly applied.").
    Under tort causation principles, an actor may be held
    liable for harm to another person if the actor's misconduct was a
    factual cause of the harm, see Restatement (Third) of Torts § 26
    (2010), and the harm resulted from the risks that made the conduct
    wrongful in the first place, meaning that it was a reasonably
    foreseeable consequence of the misconduct, see id. § 29.    In turn,
    misconduct is considered a factual cause of harm in two mutually
    exclusive situations.   The first is where the harm would not have
    occurred but for the misconduct.       See id. § 26.    This rule is
    sometimes called the "but for" causation principle.     See id. § 26
    cmt. b.   The second scenario is where the harm was brought about
    concurrently by the misconduct and an unrelated force, each of
    -40-
    which would have been sufficient by itself to trigger the harm.
    See id. § 27.   In that circumstance, the actor's misconduct was not
    a necessary condition for the harm, since the harm would have
    occurred in its absence due to the concurrent force.              See id. § 27
    cmt. a.   Nevertheless, the misconduct is regarded as a factual
    cause of the harm for policy reasons, since the actor should not
    escape liability merely because of the fortuitous operation of
    another force that also would have produced the harm on its own.
    See Dan B. Dobbs et al., The Law of Torts § 189 (2d ed. 2011) ("It
    would be a windfall [if the actor] were to escape liability for the
    harm merely because another [force] was also sufficient to cause
    the same harm."); W. Page Keeton et al., Prosser and Keeton on
    Torts § 41 (5th ed. 1984).   We refer to this rule as the concurrent
    causation principle.
    The materiality standard articulated in Brady and its
    progeny   incorporates   a   version        of    the   "but   for"   causation
    principle.   Evidence that was withheld during a criminal trial is
    material only    if   there is   a    reasonable        probability   that its
    disclosure would have altered the trial's outcome.              See Strickler,
    
    527 U.S. at 280
    ; Kyles, 
    514 U.S. at 434
    ; Bagley, 
    473 U.S. at 682
    .
    Put another way, there must be a reasonable probability that the
    defendant would not have been convicted but for the wrongful
    withholding of exculpatory evidence.             Hence, one cannot establish
    a Brady violation without showing to the requisite standard that
    -41-
    the withholding of evidence was a necessary condition for the
    conviction.   In the criminal context, this showing may result in a
    new trial or a judgment of acquittal.
    To recover damages in a civil trial based on such a
    violation, however, a § 1983 plaintiff must demonstrate a stronger
    causal link than is inherent in Brady's materiality standard.
    Having already shown a reasonable probability that he would not
    have been convicted but for the withholding of evidence, the
    plaintiff must then make the same showing by a preponderance of the
    evidence.     In     other   words,   the   factual   causation   inquiry
    essentially replicates the materiality inquiry with a heightened
    burden of proof.13
    Understood in this light, there is no place in the
    factual causation inquiry for the concurrent causation principle.
    That principle is incompatible with Brady's materiality standard.
    Whereas under the concurrent causation principle misconduct can be
    a factual cause of harm even if the harm would have happened
    anyway, see Restatement (Third) of Torts § 27 (2010), withheld
    13
    There is some logical appeal to bypassing the materiality
    inquiry and simply requiring the plaintiff to prove from the outset
    by a preponderance of the evidence that he would not have been
    convicted but for the withholding of evidence.        Nevertheless,
    materiality and causation are in fact discrete inquiries and should
    be considered separately. The threshold question in a § 1983 suit
    is whether there has been a violation of a federally secured right.
    See Baker v. McCollan, 
    443 U.S. 137
    , 140 (1979).        Materiality
    properly is a component of that question. The causation inquiry
    begins only after a violation has been established. See Sanchez,
    
    590 F.3d at 41
    .
    -42-
    evidence is never material within the meaning of Brady if its
    disclosure would have made no difference, see United States v.
    Wall, 
    349 F.3d 18
    , 23 (1st Cir. 2003).
    The second element of the traditional tort causation
    inquiry limits the scope of an actor's liability to harm that
    results from the risks that made his conduct wrongful.                         See
    Restatement       (Third)   of   Torts    §    29    (2010).      When    material
    exculpatory evidence is withheld, the obvious risk is a tainted
    conviction.        That risk is the reason for the Brady doctrine.
    Hence, once a Brady violation is established, there is no need to
    ask again whether the harm (i.e., the conviction) was foreseeable.
    Once a Brady violation has been shown, the causation inquiry in a
    § 1983 damages suit is only a "but for" inquiry pursuant to the
    preponderance of the evidence standard.
    2.   The Jury Instructions
    We now turn to the jury instructions given in the 2009
    retrial.     The judge first gave a materiality instruction that has
    not   been    challenged.14       She    then       gave   a   lengthy   causation
    14
    The materiality instruction was as follows:
    Exculpatory evidence is material when it is of a
    type that could undermine confidence in the outcome of a
    trial. It would include evidence that has the potential
    to alter a jury's assessment of the credibility of a
    significant government witness.
    In determining what is material, the question is not
    whether a defendant would more likely than not receive a
    different verdict if the evidence had been disclosed.
    -43-
    instruction, informing the retrial jury that, if it found that
    Callahan withheld material exculpatory evidence, it had to decide
    whether his misconduct caused Drumgold's conviction:
    Now, I'll address the question of
    cause, legal cause standard. If you determine
    that    Officer     Callahan    committed    a
    constitutional violation either by obtaining
    false statements or suppressing exculpatory
    evidence, and, again, material exculpatory
    evidence, you then need to address the
    relationship    between   the   constitutional
    violations that you found and Shawn Drumgold's
    conviction. That relationship is defined by
    the legal concept known as causation.
    The question is whether without the evidence he would
    receive a fair trial, understood as a trial resulting in
    a verdict worthy of confidence.
    And in considering whether a verdict worthy of
    confidence would result, you have to consider the
    setting. . . . In [the 1989 criminal trial], the burden
    of proof was beyond a reasonable doubt.               The
    [prosecution] was required to convince a unanimous jury
    beyond a reasonable doubt to sustain a conviction against
    Mr. Drumgold. Thus, one way of understanding materiality
    is to consider whether the undisclosed evidence would
    have created a reasonable doubt of the defendant's guilt.
    This instruction omitted the statement that Drumgold had to
    show a reasonable probability that he would not have been convicted
    but for Callahan's withholding of evidence. The instruction noted
    that "evidence is material when it is of a type that could
    undermine confidence in the outcome of a trial" and that "the
    question is not whether a defendant would more likely than not
    receive a different verdict if the evidence had been disclosed."
    Those are important glosses on Brady's materiality standard, but
    the centerpiece of the standard is a reasonable probability of a
    different result. See Kyles, 
    514 U.S. at 434
    . The absence of that
    formulation from the instruction detracted from the causal showing
    at the heart of the materiality inquiry. Nevertheless, there is no
    challenge to the materiality instruction on appeal, and this
    omission is not a factor in our decision.
    -44-
    Causation has two elements: Factual
    cause and proximate cause.       An act is a
    factual cause of an injury if it appears from
    the evidence that it was a substantial factor
    in bringing about the injury.[15] There may be
    15
    As explained above, an actor is liable in tort for harm to
    another person if the actor's misconduct was a factual cause of the
    harm, see Restatement (Third) of Torts § 26 (2010), and the harm
    resulted from the risks that made the conduct wrongful in the first
    place, meaning that it was a reasonably foreseeable consequence of
    the misconduct, see id. § 29. These elements traditionally have
    been referred to as "factual causation" and "proximate causation,"
    but the terms for these two concepts sometimes have been confused,
    as have the concepts themselves. See Rodríguez-Cirilo, 
    115 F.3d at 54
     (Campbell, J., concurring) (noting confusion); Fedorczyk v.
    Caribbean Cruise Lines, Ltd., 
    82 F.3d 69
    , 73 (3d Cir. 1996) (same);
    Dan B. Dobbs et al., The Law of Torts § 185 (2d ed. 2011) ("Courts
    often lump these two distinct issues together under the rubric of
    'proximate cause.'"). One particular source of confusion has been
    the "substantial factor" test used in many jurisdictions, under
    which an actor may be held liable for harm if his misconduct was a
    substantial factor in bringing about the harm and no rule of law
    relieves the actor from liability because of the manner in which
    the harm occurred. See Restatement (Second) of Torts § 431 (1965).
    Although this test was intended as the "routine standard" for
    factual causation, Restatement (Third) of Torts § 26 cmt. j (2010),
    it commonly has been misunderstood to address proximate causation,
    as well, see, e.g., Clement v. United States, 
    980 F.2d 48
    , 53 n.13
    (1st Cir. 1992); Richard W. Wright, Causation in Tort Law, 
    73 Cal. L. Rev. 1735
    , 1782 (1985).
    The modern trend, endorsed by the American Law Institute
    ("ALI"), is to retain the term "factual causation" but abandon the
    "substantial factor" test, see Restatement (Third) of Torts § 26
    cmt. j (2010), and to replace the problematic term "proximate
    causation" with "scope of liability," see id. Ch. 6, Special Note
    on Proximate Cause (2010), and thereby refocus the second component
    of the causation inquiry on whether the harm in question was among
    "those harms that result from the risks that made the actor's
    conduct tortious," id. § 29. In addition, although the ALI for
    many years employed the umbrella term "legal cause" to encompass
    both elements of the causation inquiry, see Restatement (Second) of
    Torts § 430 (1965), it recently retired that term in an effort to
    emphasize that the two elements are distinct, see Restatement
    (Third) of Torts Ch. 6, Special Note on Proximate Cause (2010).
    This trend has been embraced by a number of courts, see, e.g.,
    June v. Union Carbide Corp., 
    577 F.3d 1234
    , 1240 (10th Cir. 2009);
    -45-
    a number of factual causes of any particular
    injury; not everyone whose acts are factual
    causes of an injury is legally responsible.
    The law determines whether it is fair to hold
    someone responsible for an injury using the
    concept of proximate cause.    An act is the
    proximate cause of an injury if the injury is
    a reasonably foreseeable consequence of the
    act.
    This does not mean that the law
    recognizes only one legal cause of an injury
    or damage consisting of only one factor or
    thing or the conduct of one person, of only
    one person. On the contrary, many factors or
    things may operate at the same time either
    independently or together, to cause an injury.
    In that case, each may be a legal cause.
    Let me give you an example of legal
    causation.     Two fires are raging in the
    forest.    One started when someone dropped a
    match on the ground.      The two fires join
    together and burn down a barn. Dropping the
    match was a substantial factor in the harm of
    burning down the barn. The barn burning down
    was a reasonably probable result of dropping
    the match. In other words, the match legally
    caused the damage to the barn even if
    lightning itself would have burned it down.
    Put in the context of this case, you
    should decide whether Officer Callahan's
    wrongful conduct was a substantial factor in
    bringing about Shawn Drumgold's conviction and
    whether it was reasonably foreseeable that a
    conviction would result from his conduct.
    Thompson v. Kaczinski, 
    774 N.W.2d 829
    , 837 (Iowa 2009), and,
    properly understood, merely represents a shift in terminology, see
    Restatement (Third) of Torts § 29 cmt. j (2010). The contours of
    the causation inquiry are unchanged.
    We use the new terminology proposed by the ALI throughout this
    opinion to help us explain the error in the district judge's
    causation instruction.      It is premature to adopt the new
    terminology generally.    The district judge used the traditional
    terminology.
    -46-
    Defendant Callahan's, Officer Callahan's,
    conduct need not be the only cause nor the
    latest or the nearest cause, it is sufficient
    if it concurs with some other cause acting at
    the same time which in combination with it
    contributed to Shawn Drumgold's conviction.
    Again, concerning legal cause, I remind
    you that the plaintiff has the burden of
    proving that any constitutional violations you
    identify were the cause of the damages
    Plaintiff Drumgold has sustained.      In other
    words,   Mr.   Drumgold    must  prove    by  a
    preponderance of the evidence that Officer
    Callahan's actions in . . . failing to
    disclose material exculpatory information were
    a substantial factor in causing Mr. Drumgold's
    conviction and that the conviction was a
    reasonably foreseeable result of Officer
    Callahan's actions.     The evidence on which
    you're to evaluate cause is the trial
    transcript which is now before you of the 1989
    criminal trial.
    3.   The Standard of Review
    Callahan objects to this instruction because it included
    the concurrent causation principle. Our standard of review depends
    on whether Callahan preserved this objection.   See Colón-Millín v.
    Sears Roebuck de P.R., Inc., 
    455 F.3d 30
    , 40 (1st Cir. 2006).
    Federal Rule of Civil Procedure 51 provides a method for
    preserving objections to jury instructions.      See Surprenant v.
    Rivas, 
    424 F.3d 5
    , 15 (1st Cir. 2005).   The judge must apprise the
    parties   of   the   proposed   instructions,   consider    requested
    instructions, and note objections before charging the jury.      See
    Fed. R. Civ. P. 51(b); Booker v. Mass. Dep't of Pub. Health, 
    612 F.3d 34
    , 40-41 (1st Cir. 2010); Surprenant, 
    424 F.3d at 15
    .       "An
    -47-
    objection lodged at that time preserves the underlying issue for
    appeal."   Surprenant, 
    424 F.3d at 15
    ; see also Fed. R. Civ. P.
    51(c)(2)(A).    If, however, the judge fails to inform a party of "an
    instruction or action on a request" before the jury is charged, the
    party may object "promptly after learning that the instruction or
    request will be, or has been, given or refused."            Fed. R. Civ. P.
    51(c)(2)(B); see also Booker, 
    612 F.3d at 41
    .           A party who objects
    to an instruction must "stat[e] distinctly the matter objected to
    and the grounds for the objection."         Fed. R. Civ. P. 51(c)(1).
    Drumgold argues that Callahan not only failed to preserve
    his objection to the concurrent causation principle but invited any
    instructional error by advocating the indiscriminate application of
    traditional tort causation principles. See P.R. Hosp. Supply, Inc.
    v. Boston Scientific Corp., 
    426 F.3d 503
    , 505 (1st Cir. 2005) ("In
    general,   a   party   may   not   appeal   from   an   error   to   which   he
    contributed, either by failing to object or by affirmatively
    presenting to the court the wrong law." (internal quotation marks
    omitted)); 9C Charles Alan Wright & Arthur R. Miller, Federal
    Practice and Procedure § 2558 (3d ed. 2008) ("The so-called invited
    error rule . . . prescribes that a party may not complain on appeal
    of errors that he himself invited . . . .                Thus, a party who
    requests a jury instruction cannot complain if the instruction, or
    one substantially like it, is given by the trial judge." (footnote
    omitted) (internal quotation marks omitted)).
    -48-
    We disagree.    Before the retrial jury was charged,
    Callahan objected to the inclusion in the judge's instructions of
    the example of two fires combining to burn down a barn.            This
    example is a classic illustration of the concurrent causation
    principle, see Restatement (Second) of Torts § 432 cmt. d, illus.
    4 (1965), and Callahan's objection adequately alerted the judge to
    his concern that this principle was inapposite. Moreover, Callahan
    expressly requested a causation instruction in line with the "but
    for" causation principle:
    The jury should be instructed that they are to
    consider the Evans issues within the context
    of the entire [1989 criminal trial], and that
    they may only find for Drumgold if they find
    that the conviction would not have occurred
    but for the alleged suppression of the Evans
    evidence.
    Viewed together with the objection to the illustration of the
    concurrent causation principle, this requested instruction signaled
    an attempt to confine the causation inquiry in the 2009 retrial to
    the   "but    for"   causation   principle.    Accordingly,   we   treat
    Callahan's objection as preserved.        "We review de novo preserved
    claims of legal error in jury instructions, but we review for abuse
    of discretion claimed errors in instructions' form or wording."
    Uphoff Figueroa v. Alejandro, 
    597 F.3d 423
    , 434 (1st Cir. 2010);
    see also Portugues-Santana v. Rekomdiv Int'l, 
    657 F.3d 56
    , 60 (1st
    Cir. 2011).     In doing so, we "look to the challenged instructions
    in relation to the charge as a whole, asking whether the charge in
    -49-
    its entirety -— and in the context of the evidence —- presented the
    relevant issues to the jury fairly and adequately." Sony BMG Music
    Entm't v. Tenenbaum, 
    660 F.3d 487
    , 503 (1st Cir. 2011) (internal
    quotation marks omitted).       Even if we detect an error, a new trial
    is required only if the error was prejudicial.                See id.
    4.   Analysis
    The instructions given to the retrial jury appropriately
    presented    materiality      and   causation    as    separate,      sequential
    inquiries.16     However, the judge made a fundamental error in
    describing the substance of the causation inquiry.                She explained
    the concept of factual causation by reference to the "substantial
    factor"   test   and   then   fleshed   out     that   test    with     a   graphic
    illustration of the concurrent causation principle.               Specifically,
    she used the example of two fires combining to destroy a barn to
    underscore the point that the fire ignited by the match could be
    considered "a substantial factor in the harm of burning down the
    barn . . . even if lightning itself would have burned it down."
    Insofar as that example implied that Callahan's misconduct could be
    a factual cause of Drumgold's conviction even if Drumgold would
    16
    The special verdict form used in the retrial likewise
    presented materiality and causation as separate questions,
    directing the jury to decide first whether "the evidence withheld
    by Defendant Callahan was material" and then, if so, whether
    Callahan's withholding of that evidence "was a legal cause of Mr.
    Drumgold's conviction."
    -50-
    have been found guilty anyway, it was irreconcilable with Brady's
    materiality standard and had no place in the causation inquiry.
    The judge should have limited her discussion of factual
    causation to the "but for" causation principle.                             That is, she
    should have directed the jury to determine whether Drumgold had
    proven by a preponderance of the evidence that he would not have
    been        convicted      but    for    Callahan's      wrongful        withholding     of
    exculpatory evidence.              Instead, the judge improperly invited the
    jury    to     analyze      factual      causation     through      the     lens   of    the
    concurrent causation principle.17
    We have no confidence that the retrial jury's verdict was
    unaffected         by   the      instructional       error.        Having      linked    the
    "substantial factor" test with the concurrent causation principle,
    the judge told the jury to "decide whether Officer Callahan's
    wrongful conduct was a substantial factor in bringing about Shawn
    Drumgold's         conviction,"         and   reiterated      at   the    close    of    the
    causation          instruction      that      Drumgold       had   to     "prove    by     a
    preponderance of the evidence that Officer Callahan's actions in
    . . . failing to disclose material exculpatory information were a
    substantial factor in causing [his] conviction."                         This charge was
    nearly       the    last    thing       the   jury   heard    before      it    began    its
    17
    In fairness to the district judge, we note that the issue
    of causation in civil trials seeking damages for Brady violations
    has not been well-developed. In that legal environment, it would
    be easy to make a mistake.
    -51-
    deliberations, and it diluted the standard of liability by making
    it possible for the jury to find that Callahan's withholding of
    evidence was a factual cause of Drumgold's constitutional injury
    (i.e., his wrongful conviction) even if that evidence was not the
    "but   for"    cause      of   Drumgold's          conviction   --     the   materiality
    standard required by Brady.            That illogical possibility could only
    have prejudiced Callahan.
    It is our duty "to remain vigilant in policing the
    boundaries separating tort law from constitutional law," Nix v.
    Franklin Cnty. Sch. Dist., 
    311 F.3d 1373
    , 1379 (11th Cir. 2002),
    and to apply in the § 1983 context only those tort causation
    principles that are compatible with the underlying constitutional
    right, see Calero–Colón v. Betancourt–Lebron, 
    68 F.3d 1
    , 4 (1st
    Cir. 1995) ("[T]he essential elements of actionable section 1983
    claims derive first and foremost from the Constitution itself, not
    necessarily from the analogous common law tort.").                       The causation
    instruction given in this case clashed with Brady's materiality
    standard.          A wrongful conviction based on the withholding of
    exculpatory evidence is not redressable under § 1983 without a
    showing,      by    a   preponderance         of    the   evidence,     of    "but   for"
    causation.         The erroneous instruction here permitted the jury to
    impose   liability        even   in    the     absence     of   that     causal   nexus.
    Therefore, another retrial is necessary.                   See Allen v. Chance Mfg.
    Co.,   
    873 F.2d 465
    ,   469    (1st    Cir.     1989)    ("An    erroneous    jury
    -52-
    instruction necessitates a new trial . . . if the error could have
    affected the result of the jury's deliberations.").
    III.
    We vacate the judgment in Drumgold's favor and remand
    this case to the district court for a new trial consistent with
    this opinion.   Each party is to bear its own costs.
    So ordered.
    – Dissenting Opinion Follows --
    -53-
    LYNCH, Chief Judge, concurring in part, dissenting in
    part, and dissenting in the judgment.    I join two of the majority's
    holdings: (1) that evidence of Callahan's provision of $20 to
    Evans, as found by the 2009 jury, was not material exculpatory
    evidence, and (2) that the district court erred in its causation
    instruction and that this error prejudiced Callahan.          I dissent
    from the qualified immunity and scope of retrial holdings. On both
    of those issues, Callahan was and is entitled to judgment as a
    matter of law, and the case should not be remanded.
    I.
    As to both issues on which I dissent, some background is
    provided.
    On October 13, 1989, Shawn Drumgold was convicted in
    Massachusetts state court of the first degree murder of twelve-
    year-old Darlene Tiffany Moore. The Massachusetts Supreme Judicial
    Court (SJC) affirmed the conviction on direct appeal in 1996.          See
    Commonwealth v. Drumgold, 
    668 N.E.2d 300
     (Mass. 1996).       In 2003, a
    Massachusetts state judge held an evidentiary hearing on Drumgold's
    motion for a new trial, based on Drumgold's allegations of a series
    of newly discovered defects in the original trial. See Drumgold v.
    Commonwealth, 
    937 N.E.2d 450
    , 454 (Mass. 2010).           Following the
    hearing, the Commonwealth of Massachusetts filed a motion to vacate
    the   conviction.    
    Id.
        The   Commonwealth   denied   that   any    of
    Drumgold's allegations, taken alone, would justify a new trial, but
    -54-
    it admitted that, taken together, all of the allegations indicated
    that "justice may not have been done."          
    Id.
     at 454 n.11.    With the
    defendant and the prosecutor in agreement that a new trial was
    warranted, the state judge granted a new trial.             
    Id. at 456-57
    .
    She emphasized that her ruling did not mean that Drumgold was
    factually innocent and did not mean that police or prosecutorial
    misconduct had been established.        See 
    id. at 457
    .
    The evidence before the state judge in 2003 included: (1)
    that a key eyewitness, Mary Alexander, had been suffering from
    terminal brain cancer at the time of her testimony, a condition
    which caused memory loss, 
    id. at 454-55
    ; (2) that another key
    eyewitness, Tracie Peaks, had recanted her 1989 testimony and now
    claimed that it had been coerced, 
    id.
     at 455 n.12; (3) that a third
    identification witness had also recanted his 1989 testimony, 
    id.
     at
    456 n.15; and (4) that Ricky Evans had recanted his 1989 testimony
    and   that   there   had   been   undisclosed    promises   made   to   Evans
    regarding pending criminal charges against him and regarding the
    provision of housing and meals to him, 
    id. at 455-56
    .
    Having considered all of these grounds cumulatively, the
    judge vacated Drumgold's conviction, finding that he had been
    denied his right to a fair trial.               
    Id. at 457
    .        The judge
    emphasized that "nothing in [her] ruling in any way should be
    construed as a specific finding or determination . . . as to any
    grounds advanced by [Drumgold] in his motion for a new trial."            
    Id.
    -55-
    After the state court's decision, the Commonwealth filed a nolle
    prosequi, ending all criminal proceedings against Drumgold arising
    out of the 1989 murder.     
    Id. at 452
    .
    Drumgold then filed a lawsuit against the Commonwealth in
    state court under the Massachusetts Erroneous Convictions Law,
    Mass. Gen. Laws ch. 258D, which provides for compensation up to
    $500,000   for   victims   of   wrongful   convictions,   
    id.
       §   5.   On
    application for direct appellate review of the denial of the
    Commonwealth's motion for summary judgment in that case, the SJC
    ruled that Drumgold was an eligible claimant under the statute.
    Drumgold, 937 N.E.2d at 452; see Mass. Gen. Laws ch. 258D, § 1.          As
    the SJC's decision made clear, the combination of the various
    grounds offered in the new trial motion, and particularly the
    allegations regarding Alexander, were very serious.        See Drumgold,
    937 N.E.2d at 457-58.      The present appeal involves only a portion
    of the fourth ground described above. The state case settled after
    remand; there is no public record of the amount the Commonwealth
    paid in settlement.
    Meanwhile, in 2004, Drumgold also filed a federal lawsuit
    that led to this appeal.18 In the district court, Drumgold asserted
    claims under 
    42 U.S.C. § 1983
     and Massachusetts General Laws ch.
    12, § 11I, against the City of Boston and three police officers,
    18
    Drumgold filed his suit under the Erroneous Convictions Law
    separately because that statute provides for exclusive jurisdiction
    in Massachusetts Superior Court. Mass. Gen. Laws ch. 258D, § 3.
    -56-
    including Callahan.       At the first trial of Drumgold's claims, in
    2008, the jury concluded that Callahan had not in fact withheld or
    manufactured evidence relating to Mary Alexander or Tracie Peaks.
    As to Ricky Evans, the 2008 jury found that Callahan had not
    solicited false statements from him regarding the night of the
    murder and had only withheld evidence relating to certain cash
    payments to Evans, the amount of which the jury did not determine.
    On the twenty-fifth day of trial, the jury hung on the question of
    whether those       payments   had   been   a   legal cause    of Drumgold's
    injury.19
    Nonetheless, the district court granted a retrial on all
    of Drumgold's claims relating to Ricky Evans.           As a result of the
    second trial, in 2009, Drumgold obtained a $14 million verdict --
    approximately a million dollars per year for each year he spent in
    prison, a    rate    we   have described as       "extremely   generous"   in
    wrongful conviction cases.       Limone v. United States, 
    579 F.3d 79
    ,
    106 (1st Cir. 2009).      Unlike the panoply of reasons the state court
    gave as the basis for vacating Drumgold's conviction, the basis for
    the 2009 damages award was solely that Callahan had withheld
    evidence of housing benefits and money benefits he had provided to
    19
    The jury rejected all theories of liability for the other
    police officer who remained as a defendant in the 2008 trial. The
    district court bifurcated Drumgold's claims against the City of
    Boston from his claims against the individual police officers. The
    portion of the case involving the City is stayed pending the
    outcome of this appeal.
    -57-
    Ricky Evans.   See Drumgold v. Callahan, 
    806 F. Supp. 2d 405
    , 408
    (D. Mass. 2011).   That verdict was infected with error due to its
    jury instructions, as the majority holds. In addition, part of the
    2009 jury's verdict directly contradicted part of the jury's
    decision in the first trial: the 2008 jury determined that Callahan
    had not withheld evidence about housing Evans in a hotel; the 2009
    jury found that he had.
    II.
    A.   Qualified Immunity
    In my view, the law requires that Callahan be granted
    qualified immunity.20
    In a qualified immunity inquiry, the court must ask (1)
    whether the plaintiff has made out a violation of a constitutional
    right, and (2) whether that right was "clearly established" at the
    20
    Callahan has not waived his qualified immunity argument.
    He raised it at both the 2008 and 2009 trials, including a lengthy
    colloquy at the jury charge conference in 2008 regarding the
    applicable law. See Lynch v. City of Boston, 
    180 F.3d 1
    , 13 n.9
    (1st Cir. 1999) ("[Federal Rule of Civil Procedure] 50(a)(2) is
    designed to prevent unfair surprise and to provide the responding
    party with an opportunity to correct any deficiencies in her
    proof.   Our review of the record demonstrates that [plaintiff]
    could hardly have been surprised by [defendant]'s assertion of
    qualified immunity." (citation omitted)). Moreover, when Callahan
    again argued for qualified immunity in his renewed motion for
    judgment as a matter of law following the 2009 jury's verdict,
    Drumgold did not contend in his opposition to that motion that
    Callahan had waived the argument. Because Drumgold never argued
    waiver in the district court, the trial judge did not address the
    issue in her ruling on Callahan's post-trial motions.          See
    Drumgold, 
    806 F. Supp. 2d at 417-19
    . If anything, then, it is
    Drumgold who has waived the argument that Callahan waived the
    qualified immunity defense.
    -58-
    time of the violation -- although the court need not necessarily
    address the questions in that order.          See Maldonado v. Fontanes,
    
    568 F.3d 263
    , 269-70 (1st Cir. 2009) (citing Pearson v. Callahan,
    
    555 U.S. 223
    , 232, 236 (2009)).       The "clearly established" prong,
    in turn, encompasses two questions: whether the right was, in
    general, "sufficiently clear that a reasonable official would
    understand that what he [was] doing violate[d] that right," 
    id. at 269
     (quoting Anderson v. Creighton, 
    483 U.S. 635
    , 640 (1987))
    (internal     quotation    mark   omitted);   and   whether,   under   the
    particular facts of the case, a reasonable defendant would have
    understood that he was violating the right, 
    id.
    As the majority recognizes, the $20 that Callahan gave to
    Evans, as found by the 2009 jury, was not material exculpatory
    evidence.      Drumgold thus failed to make out a constitutional
    violation as to the money, and Callahan is entitled to qualified
    immunity on that issue under the first prong of the qualified
    immunity analysis.        The only remaining issue, then, is whether
    Callahan was entitled to qualified immunity on the claim that he
    did not disclose to the prosecution in Drumgold's murder case that
    Ricky Evans was being housed in a hotel.
    Callahan was clearly entitled to immunity, on several
    grounds.21     The law was not clearly established in 1989 that
    21
    As I explain below in section II.B, Callahan was entitled
    to the benefit of the first jury's verdict on the hotel housing
    issue. The 2008 jury found that he did not withhold exculpatory
    -59-
    Callahan was under any duty to disclose such information, and a
    reasonable police officer in Callahan's position would not have
    understood that his alleged actions regarding Evans's housing
    violated a constitutional right.
    This court has explained very recently that, at least
    until 1995, it was not clearly established that the affirmative
    disclosure obligation imposed on prosecutors by Brady v. Maryland,
    
    373 U.S. 83
     (1963), applied to police officers.    See Haley v. City
    of Boston, 
    657 F.3d 39
    , 48-49 (1st Cir. 2011).       "By its terms,
    Brady applied only to prosecutors."   
    Id. at 48
    .   Even after 1995,
    when the Supreme Court decided Kyles v. Whitley, 
    514 U.S. 419
    (1995), the role of police officers in the Brady calculus remained
    "indirect," as that case held "that the disclosure obligation
    imposed by Brady extends to evidence known only to police officers,
    but that the responsibility for obtaining and disclosing such
    evidence remains the duty of the prosecutor."     Haley, 
    657 F.3d at
    49 (citing Kyles, 
    514 U.S. at 437-38
    ).
    It certainly was not clearly established in 1989 that a
    police officer in Callahan's position had an affirmative obligation
    under Brady to disclose potential impeachment evidence of the sort
    evidence relating to Evans staying in a hotel and being provided
    with meals. Based on the 2008 jury's verdict, Callahan should have
    been granted qualified immunity on the hotel issue under the first
    prong of the qualified immunity inquiry. However, even if the 2009
    jury's verdict on this point were permissible, Callahan should have
    been granted qualified immunity on that verdict under the second
    prong of the analysis, as I explain in this section.
    -60-
    at issue here.      Indeed, it is not clearly established today.           See,
    e.g., Reid v. Simmons, 
    163 F. Supp. 2d 81
    , 84 (D.N.H. 2001)
    (describing "the circumstances under which police officers may be
    held    civilly    liable   for   Brady   violations"    as    "a   matter    of
    considerable uncertainty"), aff'd, 47 Fed. App'x 5 (1st Cir. 2002)
    (per curiam).      Compare Jean v. Collins, 
    221 F.3d 656
    , 660 (4th Cir.
    2000) (en banc) (Wilkinson, J., concurring in the judgment) ("[T]o
    speak of the duty binding police officers as a Brady duty is simply
    incorrect.      The Supreme Court has always defined the Brady duty as
    one that rests with the prosecution."), with Newsome v. McCabe, 
    256 F.3d 747
    ,    752-53   (7th   Cir.   2001)   ("The   Brady   principle     was
    announced in 1963, and we [have] applied it . . . to affirm a hefty
    award of damages against [police] officers who withheld exculpatory
    information in 1981.").
    Both of the parties and the trial judge conceived of the
    housing and money issues as Brady issues throughout the district
    court proceedings.22 For example, at the pretrial conference before
    22
    This treatment was distinct from the parties' and the
    court's view of Drumgold's allegations that Callahan had
    manufactured evidence and convinced Evans to give false testimony.
    Although the framing of these latter allegations was inconsistent
    throughout the parties' various filings, they were frequently
    understood as involving due process rights other than those defined
    by Brady. The hotel and money issues, by contrast, were
    consistently treated as Brady issues. Callahan's arguments about
    the jury instructions on state of mind, cited by the majority, were
    premised on the assumption that Brady applied to police officers
    under Callahan's circumstances, an assumption later negated by
    Haley (a case decided in 2011, after both of Drumgold's trials were
    over).
    -61-
    the 2008 trial, the district court described one of the "principal
    constitutional rights" at issue in the case as "Brady violations."
    In both 2008 and 2009, Drumgold relied on Brady (and on Kyles -- a
    case that post-dated Callahan's alleged actions) in requesting jury
    instructions on a police officer's duty to disclose evidence to the
    prosecution.    Before the 2008 trial, the district court issued a
    document titled "Proposed Brady Instruction."       In the charge
    conference preceding the 2008 jury instructions, Callahan's counsel
    engaged in a lengthy discussion with the court regarding the lack
    of clarity about how to apply Brady to the situation in Drumgold's
    case. In Callahan's renewed motion for judgment as a matter of law
    following the 2009 trial, and in Drumgold's opposition to that
    motion, the parties argued for or against entering judgment for
    Callahan on the basis of whether a Brady violation had occurred.
    The district court echoed this understanding at the hearing on
    Callahan's motion, and a Brady theory was the basis of the court's
    denial of qualified immunity.    See Drumgold, 
    806 F. Supp. 2d at 409, 417-19
    .
    The district court's reason for denying immunity was
    error, as the majority admits. Because Callahan was not subject to
    a clearly established Brady duty in 1989, any alleged violation of
    Brady's dictates cannot be the basis for denying Callahan qualified
    immunity.      The district court's reasoning cannot survive our
    decision in Haley.    On this point, the majority and I agree.
    -62-
    However,     the    majority      then    attempts    to     rescue    the
    district court's qualified immunity ruling by instead relying on a
    line of pre-Brady cases that neither the parties nor the trial
    judge     ever    used   to   support   their     arguments       about    the    hotel
    evidence. In fact, these cases -- primarily Mooney v. Holohan, 
    294 U.S. 103
    , 112-13 (1935) (per curiam), and Pyle v. Kansas, 
    317 U.S. 213
    , 216 (1942) -- are not even cited in Drumgold's brief before
    this court.23
    There are a number of problems with the majority's
    argument.        First, the Mooney line of cases is an afterthought, not
    briefed by the parties nor explicated in the record.                    It is unfair
    to Callahan to deny immunity based on an argument that was not
    preserved and as to which he had no notice.                 See DeMayo v. Nugent,
    
    517 F.3d 11
    , 15 (1st Cir. 2008) (stating that defendants who had
    used one Fourth Amendment theory to justify their actions before
    the district court could not "switch their theories on appeal" to
    a different Fourth Amendment reasoning); United States v. Slade,
    
    980 F.2d 27
    , 31 (1st Cir. 1992) (rejecting argument that "only new
    facts and not new arguments about those facts are prohibited from
    debuting    in     the   court   of   appeals"        and   concluding     that    "the
    23
    In 2008, Drumgold did request two jury instructions based
    on these cases, but they both addressed the allegation that
    Callahan had manufactured Evans's testimony, not the allegation
    that he had withheld evidence of benefits. Mooney and Pyle are
    otherwise absent from Drumgold's pleadings both in the district
    court and in this appeal.
    -63-
    raise-or-waive rule applies with full force when an appellant tries
    to present a new theory about why facts previously placed on record
    are determinative").       This court may not create an argument for a
    party and may not deny immunity based on a different theory than
    that presented at trial.      Such restraint is particularly important
    in the context of qualified immunity, which, after all, encompasses
    immunity from having to go to trial at all.
    The majority's rejoinder that a mere citation to Brady
    without a citation to Mooney and Pyle suffices is off point.24
    Callahan lacked fair notice of the argument that the hotel evidence
    -- without more -- implicated a Mooney-based due process right. As
    explained above, all involved in the trial believed that the hotel
    evidence issue was governed by Brady.            It is only the majority
    which has recharacterized the hotel claim as a non-Brady claim.
    The majority appears to take the position that this
    distinction among various due process arguments means Brady does
    not govern.      Not so.   As we stated in Haley, it is necessary to
    distinguish   Brady-based     claims    from   Mooney-based     claims   when
    conducting a qualified immunity analysis. See 657 F.3d at 46.            The
    two categories do not always cover the same types of claims,
    because   they    implicate    two   different    facets   of   a   criminal
    24
    This is not about whether Callahan lacked fair notice that
    Drumgold had alleged a due process violation based on the
    intentional use of (non-hotel and cash) false evidence, a claim
    that, if proved, could have fallen within the scope of Mooney and
    Pyle.
    -64-
    defendant's due process rights: under Mooney, the right to be free
    from a deliberately contrived conviction, and under Brady, the
    right   to   receive    material    exculpatory      evidence   known    to   the
    prosecution regardless of the prosecutor's good or bad faith.
    The majority recognizes that this court has been "careful
    to distinguish" between the principles of Mooney and Brady.                   Yet
    the majority then goes on to elide this very distinction by
    treating "Drumgold's invocation of Brady as shorthand for his full
    complement of due process rights."            This conflation of the two
    types of due process rights does not comport with our precedent.
    The only possible way to connect Drumgold's explicitly Brady-based
    claims regarding the hotel to his apparently Mooney-based claims
    regarding intentional framing would be to treat the hotel evidence
    as   proof   that    Callahan   had    induced    Evans    to   give    perjured
    testimony.    But, as I detail below, both juries found precisely to
    the contrary: they rejected the allegation that Callahan had
    elicited     false     statements     from   Ricky    Evans     about    Evans's
    observations on the night of the murder. Without even this tenuous
    connection to Mooney, all that is left is a Brady claim, which is
    exactly how the parties argued the hotel question and how the
    district court decided Callahan's motion for judgment as a matter
    of law following the final 2009 verdict.                  That is why it is
    inappropriate for this court to now insert a Mooney argument where
    none existed before -- and even more, to do so to defeat immunity.
    -65-
    On this basis alone, Mooney and Pyle cannot provide a
    justification for denying Callahan immunity.    But even if one were
    to accept arguendo that Mooney and Pyle may be brought late to the
    case, and the theory of liability altered on appeal, the juries'
    findings preclude the conclusion that these cases defeat Callahan's
    argument for qualified immunity.    Under the facts as found by both
    the 2008 and 2009 juries, a reasonable police officer in Callahan's
    position in 1989 would not have known that his actions ran afoul of
    Mooney and Pyle, and, in fact, would have had every reason to think
    they did not.
    The majority states that Mooney and Pyle identified a due
    process violation where the state procures a conviction by the
    knowing use of perjured testimony and the deliberate suppression of
    exculpatory evidence.25    See Mooney, 
    294 U.S. at 112-13
    ; Pyle, 
    317 U.S. at 216
    .    Since the rule of these cases was clearly established
    25
    The majority characterizes this principle as "the deliberate
    suppression aspect of Brady." But Mooney and Pyle, having preceded
    Brady, cannot fairly be called an "aspect" of the latter case.
    While the Brady Court did describe its holding as an "extension" of
    Mooney and Pyle, see 
    373 U.S. at 86
    , the earlier cases stand for
    their own previously established proposition, which is independent
    of the later development of Brady and its progeny.       As I have
    explained above, there are important differences between the due
    process rights identified in each line of cases.
    In Mooney, the Court held that, after exhaustion of state
    remedies, the federal writ of habeas corpus is available to state
    prisoners who assert, with some colorable support, that state
    prosecutors knowingly used perjured testimony against them and then
    knowingly suppressed evidence which could have been used to counter
    the perjured testimony.    See 
    294 U.S. at 109-10
    . Pyle, a very
    short opinion, merely states that such allegations are sufficient
    to state a claim for habeas corpus. See 
    317 U.S. at 215-16
    .
    -66-
    in   1989,   the   majority   reasons,    Callahan   is   not   entitled    to
    qualified immunity, because he deliberately suppressed evidence.
    That is not what the juries' findings establish.                While, in my
    view, Callahan was entitled to qualified immunity as a legal matter
    when the district court erroneously denied it on Brady grounds, the
    juries' verdicts certainly meant he was entitled to immunity.
    Drumgold's original complaint alleged that Callahan had
    fed Evans details of the crime and had "suggested" that Evans
    select Drumgold as the shooter from an array of photographs.               The
    complaint separately alleged that Callahan had promised Evans
    assistance with his pending criminal charges and had failed to
    disclose the hotel or cash assistance.26       But unlike in other cases
    where, because of their procedural postures, we have had to accept
    such allegations in the light most favorable to the plaintiffs,
    see, e.g., Haley, 
    657 F.3d at 46
    ; Limone v. Condon, 
    372 F.3d 39
    , 43
    (1st Cir. 2004), here we have the benefit of a jury's findings upon
    a fully developed record.      As material to the purported Mooney and
    Pyle theory and the immunity question, those findings rejected all
    of Drumgold's relevant allegations.
    The 2008 jury found that Callahan had not manufactured
    evidence, withheld evidence, or procured false statements regarding
    Evans's observations on the night of the murder, Evans's stay in
    26
    The complaint did not allege that disclosure of the
    information about benefits would have revealed the allegedly
    manufactured testimony.
    -67-
    the hotel, or the disposition of Evans's criminal cases. That jury
    also rejected allegations that Callahan had manufactured evidence
    or procured false statements with regard to Mary Alexander and
    Tracie Peaks.      These   findings   alone   required   immunity   to   be
    granted, as I explain.
    The 2009 jury did not reconsider the allegations relating
    to witnesses other than Evans, and it found again that Callahan had
    not obtained any false statements from Evans regarding the night of
    the murder and had not withheld evidence relating to Evans's
    criminal charges.     The 2009 jury did find that Callahan had
    withheld evidence regarding the housing and money provided to
    Evans.   But as the majority has explained, withholding information
    about $20 was no constitutional violation at all.
    The juries' findings clearly demonstrate that this is not
    a case about the deliberate creation of false evidence, the knowing
    submission of perjured testimony, or the attempt to frame an
    unwitting suspect -- that is, the types of misconduct contemplated
    by Mooney and Pyle.    See, e.g., Limone, 
    372 F.3d at 44
     (applying
    Mooney and Pyle to deny dismissal on qualified immunity grounds
    where plaintiff credibly alleged that police officers had developed
    a key witness's perjured testimony in order to cover for the real
    murderers).     Rather, it is a case about affirmative disclosure
    obligations.
    -68-
    Mooney       and    Pyle    did    not   clearly      establish    a    rule
    governing   what     a    police       officer    must    affirmatively     disclose;
    indeed, Brady itself recognized that the earlier cases did not
    establish affirmative disclosure obligations, as it described its
    own holding as "an extension" of Mooney.                  
    373 U.S. at 86
    .     Nothing
    in Mooney or Pyle would have put Callahan on notice that the
    Constitution required him to disclose that Evans had been housed at
    a hotel.    In fact, that is a common accommodation to secure the
    attendance at trial of a prosecution witness, and hardly surprising
    information to the criminal bar.
    In Limone, we held that, as of 1967, it was clearly
    established under Mooney that police officers were prohibited from
    "deliberately fabricating evidence and framing individuals for
    crimes they did not commit."             
    372 F.3d at 45, 47-48
    .           A reasonable
    officer in Callahan's position in 1989 would not have viewed the
    alleged nondisclosure of the hotel accommodations as falling within
    that proscription. Such an officer would have viewed those actions
    as, if anything, falling under Brady, and no contemporaneous case
    law held to the contrary.
    The Supreme Court has recently reiterated that to deny
    qualified   immunity,          "existing      precedent    must    have    placed    the
    statutory or constitutional question beyond debate."                      Ashcroft v.
    al-Kidd, 
    131 S. Ct. 2074
    , 2083 (2011).               The majority's conclusions
    cannot be squared with this command.
    -69-
    Although   Mooney   and   Pyle   may   support     a   denial    of
    qualified immunity where, at the motion to dismiss stage, the
    plaintiff   has   credibly   alleged     that   the   police   committed      a
    particularly egregious act of deliberately concealing material
    exculpatory evidence from prosecutors, see Haley, 
    657 F.3d at
    49-
    51, this is not such a case.     Nor is it even close to being such a
    case.     The juries' findings do not permit any inference that
    Callahan's actions were part of an attempt to frame Drumgold
    through perjured testimony.     Because the juries rejected the claim
    that Callahan had procured false statements from Evans about the
    night of the murder, the framing theory must fall away.                     If
    Callahan did not induce Evans to lie, the hotel lodging could not
    have been evidence of an inducement to lie.
    Further, in the instances where the juries did find that
    Callahan withheld evidence, they made no express finding that
    Callahan acted with the purpose of suppressing such evidence.               The
    holdings of Mooney, Pyle, and their progeny prohibit behavior that
    is characterized by specific intent: they hold that state actors,
    knowing that certain evidence or testimony is false, must not
    deliberately use that evidence for the purpose of obtaining a
    tainted conviction.27    Because 
    42 U.S.C. § 1983
     does not provide a
    27
    See Mooney, 
    294 U.S. at 112
     ("[D]ue process . . . cannot be
    deemed to be satisfied . . . if a state has contrived a conviction
    through the pretense of a trial which in truth is but used as a
    means of depriving a defendant of liberty through a deliberate
    deception of court and jury by the presentation of testimony known
    -70-
    source of substantive rights, but rather provides "a method for
    vindicating federal rights elsewhere conferred," Baker v. McCollan,
    
    443 U.S. 137
    , 144 n.3 (1979), a § 1983 plaintiff who alleges a
    violation of the constitutional principle recognized in Mooney and
    Pyle must prove that the defendant had the state of mind those
    cases require.   See Graham v. Connor, 
    490 U.S. 386
    , 394 (1989)
    ("The validity of the [§ 1983] claim must . . . be judged by
    reference to the specific constitutional standard which governs
    that right.").    Given all of the ambiguity as to disclosure
    obligations outlined above, as well as the juries' findings, this
    record requires that immunity be granted.
    It is clear that there was no finding of specific intent.
    Not only were the district court's jury instructions on state of
    to be perjured."); Pyle, 
    317 U.S. at 215-16
     ("Petitioner's papers
    are inexpertly drawn, but they do set forth allegations that his
    imprisonment resulted from perjured testimony, knowingly used by
    the State authorities to obtain his conviction, and from the
    deliberate suppression by those same authorities of evidence
    favorable to him."); Napue v. Illinois, 
    360 U.S. 264
    , 269 (1959)
    (recognizing "[t]he principle that a State may not knowingly use
    false evidence, including false testimony, to obtain a tainted
    conviction"); Limone, 
    372 F.3d at 45
     ("[T]hose charged with
    upholding the law are prohibited from deliberately fabricating
    evidence and framing individuals for crimes they did not commit.");
    Haley, 
    657 F.3d at 49
     ("Deliberate concealment of material evidence
    by the police, designed to grease the skids for false testimony and
    encourage wrongful conviction, unarguably implicates a defendant's
    due process rights."). Compare Brady, 
    373 U.S. at 87
     (specifying
    that the due process right recognized in that case applies
    "irrespective of the good faith or bad faith of the prosecution").
    -71-
    mind confusing or even contradictory in both trials,28 but because
    the court stated that it was supposed to be giving a Brady
    instruction, the particular state of mind requirements of Mooney
    and Pyle never entered the picture.         The 2008 verdict slip, which
    essentially exonerated Callahan, made no reference to his state of
    mind    at   all.   The   2009   verdict   slip   asked   whether   Callahan
    "intentionally or recklessly" withheld evidence, so the jury could
    have found liability without finding specific intent.29
    28
    In 2008, the trial judge told the jury that in order to find
    a § 1983 violation, "it's not necessary to find that the defendants
    had any specific intent to deprive the plaintiff of his
    constitutional rights[.] . . . [T]he plaintiff is entitled to
    relief if the defendant intended the actions which resulted in a
    violation of his constitutional right."       Yet the judge later
    instructed that "[i]n order to prevail on a claim that defendants
    suppressed exculpatory evidence, the plaintiff must prove that one
    or both of the defendants knew of certain material exculpatory
    evidence and     intentionally   and  deliberately   withheld   the
    information from the prosecutor." Callahan's counsel pointed out
    this contradiction in a colloquy just before closing arguments and
    objected to the instructions after they were given. In the 2009
    trial, the judge first instructed the jury that the § 1983 charge
    required Drumgold to show "that the defendant either intentionally
    or recklessly committed the action which then resulted in a
    violation of the plaintiff's constitutional rights," then that
    Callahan would be liable if he "knowingly and deliberately withheld
    any material exculpatory evidence from the prosecutor."
    29
    I do not agree with the majority's suggestion that
    recklessness is sufficient to satisfy Mooney's (and related cases')
    state of mind requirement. The case that the majority cites for
    this proposition, Tennison v. City and County of San Francisco, 
    570 F.3d 1078
     (9th Cir. 2009), addressed the state of mind required to
    show a Brady-based § 1983 violation in a situation where Brady was
    held to apply to police inspectors.       See id. at 1087-88. As
    detailed above, the Mooney and Pyle standard is distinct from the
    Brady standard. The fact that Callahan invoked "recklessness" in
    his memorandum of law regarding jury instructions is of no moment
    when the standard he invoked was inapplicable.
    -72-
    Beyond that, the evidence at trial showed that, in 1989,
    Callahan   had   informed   at   least   one   member   of   the   district
    attorney's office about Evans's staying in the hotel, although he
    apparently did not tell the specific prosecutor in the Drumgold
    murder trial.      See Drumgold, 
    806 F. Supp. 2d at
    410-11 & nn.5-6.
    This evidence of disclosure demonstrates that Callahan was not
    deliberately hiding the information from the district attorney's
    office in order to procure Drumgold's conviction.30
    Under    these   circumstances,     it   unduly   strains   the
    principle recognized in Mooney and Pyle to hold that a reasonable
    officer in Callahan's position would have known that failing to
    disclose the hotel evidence would be a violation of Drumgold's due
    process rights.     Where, as here, the jury's findings do not permit
    30
    In denying Callahan's 2009 post-trial motion for qualified
    immunity, the district court relied on the theory that Callahan had
    failed to fulfill his Brady obligation because he had reported the
    hotel information to the wrong prosecutor. Drumgold, 
    806 F. Supp. 2d at 418-19
    . This was incorrect under Brady and is even more so
    under Mooney and Pyle.
    The answer to the question of to whom (and how) a police
    officer ought to disclose potentially exculpatory evidence was not
    clearly established in 1989, and it is still not clearly
    established today. Neither party, nor the district court, provided
    controlling authority or even anything approaching a consensus of
    persuasive authority on this issue. See Wilson v. Layne, 
    526 U.S. 603
    , 617 (1999).     There was no support for denying qualified
    immunity on this basis, even under the district court's Brady-based
    reasoning.    And under the majority's non-Brady theory, if a
    reasonable officer in Callahan's position truthfully disclosed
    evidence to the district attorney's office -- even if the
    disclosure were later adjudged to be legally insufficient -- he
    would reasonably believe that he was not violating Mooney and
    Pyle's prohibition of intentional framing.
    -73-
    a theory of intentional framing, nor include a finding of the
    requisite knowledge or intent, the pre-Brady cases are not on
    point.    To hold otherwise is to blur the line between Brady's no-
    fault nondisclosure obligation and Mooney and Pyle's proscription
    against the knowing and deliberate use of false evidence.
    This is exactly the kind of situation for which qualified
    immunity was designed, even against the background of Haley and
    Limone.   Callahan's circumstances are a far cry from those alleged
    in those two cases, where plaintiffs claimed that the police were
    "intentionally framing an accused person" by a "deliberate attempt
    to   secure    a   conviction,   without   regard   to   actual   guilt   or
    innocence," Haley, 
    657 F.3d at
    46 -- not that the police disclosed
    evidence in a less-than-thorough manner. The doctrine of qualified
    immunity "protects all state actors except 'the plainly incompetent
    [and] those who knowingly violate the law.'" Haley, 
    657 F.3d at 47
    (quoting Malley v. Briggs, 
    475 U.S. 335
    , 341 (1986)).         The juries'
    findings reveal that Callahan does not fall into either category.
    Remanding the case for yet a third trial, when Callahan was clearly
    entitled to qualified immunity no later than the first trial,
    denies him the benefit of those juries' findings, in violation of
    his Seventh Amendment rights and his immunity rights.         Callahan is
    entitled to qualified immunity, and judgment should enter for him
    on that basis.
    -74-
    B.   The Scope of the 2009 Retrial
    The district court erred in ordering a retrial of the
    hotel issue before the second jury, abusing its discretion. It did
    so in derogation of Callahan's Seventh Amendment rights.          The
    retrial jury should not have been permitted to reexamine the
    question of whether Callahan withheld the hotel evidence, since
    that question was resolved in his favor during the 2008 trial.
    That question was not so inextricably intertwined with the money
    issue as to require a full retrial.     The district court should have
    ordered a retrial on the money issue only: that is, the court
    should have asked the second jury to determine whether Callahan had
    deliberately suppressed evidence that he gave Evans money, the
    amount of such money (if any), whether the sum was material, and
    whether the withholding of that information caused Drumgold's
    injury.
    In the 2008 trial, the district court divided the jury
    deliberations into two phases. In the first phase (the "violation"
    phase), the jury was to decide, inter alia, whether Callahan
    violated Drumgold's right to a fair trial by withholding evidence
    that Callahan arranged free housing for Evans and/or that Callahan
    gave Evans "substantial amounts of money."31     If the jury answered
    31
    The relevant special verdict questions read as follows:
    Has the Plaintiff, Shawn Drumgold, proven by a
    preponderance of the evidence that Defendant Timothy
    Callahan violated his right to a fair trial by
    -75-
    "yes" to either or both of these questions, the second phase (the
    "causation" phase) would ask the jury to decide whether such
    withholding was the cause of Drumgold's injury. The 2008 jury thus
    potentially faced four questions: (1) whether Callahan withheld
    housing evidence; (2) whether Callahan withheld money evidence; (3)
    whether withholding the housing evidence caused Drumgold's injury;
    and (4) whether withholding the money evidence cause Drumgold's
    injury.
    In       the   first   phase,   the   2008    jury   determined   that
    Callahan had not withheld evidence regarding the housing but had
    withheld evidence regarding the money; that is, it answered "no" to
    question 1 and "yes" to question 2.             Following the verdict in the
    first phase, the parties declined the district court's suggestion
    that the jury be instructed to clarify what amount of money
    constituted    a    "substantial    amount."       In   the    second   phase of
    deliberations, the jury never reached question 3 because it had
    answered "no" to question 1.         It then hung on question 4: whether
    withholding exculpatory evidence from prosecutors,
    manufacturing evidence, and/or obtaining false statements
    regarding Ricky Evans being housed at a hotel and
    provided with meals?
    Has the Plaintiff, Shawn Drumgold, proven by a
    preponderance of the evidence that Defendant Timothy
    Callahan violated his right to a fair trial by
    withholding exculpatory evidence from prosecutors,
    manufacturing evidence, and/or obtaining false statements
    regarding Ricky Evans being given substantial amounts of
    money?
    -76-
    Callahan's provision of money to Evans had caused Drumgold's
    injury.
    After the district court declared a mistrial, Callahan
    moved for entry of final judgment as to, inter alia, the housing
    issue, and he sought to restrict the scope of the retrial to the
    causation question with regard to the money.   Because the housing
    issue was separate from the money issue and had been decided by a
    jury, it should not have been retried.
    The district judge, however, denied Callahan's motion,
    stating that a limited retrial which did not reopen the housing
    questions was not feasible because
    [a] second jury would obviously have to be
    instructed   that   Callahan     had   violated
    Drumgold's   civil   rights   by   giving   him
    "substantial amounts of money" and not
    disclosing it.   The jury would be left with
    the ambiguity of what "substantial money"
    meant -- an issue wholly unresolved in the
    first trial, notwithstanding the Court's
    efforts to seek further clarification.      And
    the only way to resolve that ambiguity would
    be to relate each side's evidence concerning
    the treatment of Ricky Evans . . . .         In
    short, all aspects of Ricky Evans's portion of
    this case would be involved.
    On this basis, the district judge allowed the retrial jury to
    revisit both "violation" questions -- that is, whether Callahan had
    failed to disclose that he had given housing benefits to Evans and
    whether he had failed to disclose that he had given money to Evans.
    This rationale does not in fact explain why the housing issue
    should have been subject to retrial.
    -77-
    A   partial   retrial   is   permissible   under   the    Seventh
    Amendment when some, but not all, issues in a case have been
    properly and conclusively resolved by a jury verdict.               Gasoline
    Prods. Co. v. Champlin Refining Co., 
    283 U.S. 494
    , 500 (1931).            In
    order for a partial retrial to be appropriate, it must "clearly
    appear[]" that the remaining issues are "so distinct and separable
    from the others that a trial of [them] alone may be had without
    injustice."    
    Id.
    The decision whether to grant a full or a partial retrial
    is generally committed to the discretion of the trial judge, see
    Sprague v. Boston & Me. Corp., 
    769 F.2d 26
    , 28 (1st Cir. 1985), and
    thus our review is for abuse of discretion, see Winn v. Lafayette
    Town House, 
    839 F.2d 835
    , 837 (1st Cir. 1988); Sprague, 
    769 F.2d at 28
    .   An error of law, here an error as to the dictates of Gasoline
    Products, constitutes an abuse of discretion. A district court may
    also abuse its discretion when it misapprehends the nature of the
    relationship between the issues sought to be retried, Winn, 
    839 F.2d at 836-37
    , or when it does not give an adequate basis in the
    record for its determination that a full retrial is necessary,
    Crane v. Consol. Rail Corp., 
    731 F.2d 1042
    , 1049-51 (2d Cir. 1984)
    (Friendly, J.). All three of these types of problems appear in the
    district court's retrial order.
    First, neither of the primary rationales for ordering a
    full rather than a partial retrial are present here.          Generally, a
    -78-
    full retrial is necessary when (1) the original verdict represented
    a compromise among jurors who could not otherwise agree on multiple
    issues, or (2) the error infecting one issue in the verdict likely
    spread to the others.        See 11 Wright & Miller, Federal Practice &
    Procedure § 2814 (2012); see also Phav v. Trueblood, Inc., 
    915 F.2d 754
    , 767-68 (1st Cir. 1990) (explaining compromise verdicts and
    citing cases).      Indeed, in Vizzini v. Ford Motor Co., 
    569 F.2d 754
    (3d Cir. 1977), the court observed that partial retrials should be
    granted "only in those cases where it is plain that the error which
    has crept into one element of the verdict did not in any way affect
    the determination of any other issue."                    
    Id. at 760
     (quoting Romer
    v.   Baldwin,   
    317 F.2d 919
    ,    922-23         (3d    Cir.     1963))    (internal
    quotation marks omitted).
    Significantly,       when            a        jury     answers       special
    interrogatories rather than giving a general verdict, courts have
    more readily preserved the jury's findings and ordered partial
    rather than full retrials.       See, e.g., LaPlante v. Am. Honda Motor
    Co., 
    27 F.3d 731
    , 738 (1st Cir. 1994) (remanding for new trial only
    on liability and not on damages, where damages award was distinct
    and separable, "particularly" because the first jury answered
    "detailed   interrogatories"         on    how       it    arrived    at   the   damages
    number). In Crane v. Consolidated Rail Corp., 
    731 F.2d 1042
    , Judge
    Friendly    noted     that     when        a     trial       court      uses     special
    interrogatories, the "trial or reviewing court may be reasonably
    -79-
    certain that an erroneous verdict was reached independent of
    another verdict," and unless there are "obvious inconsistencies,"
    the court should presume that each of the jury's answers is a "good
    faith response[]    to   the   question[]   presented."     
    Id. at 1050
    (quoting Akermanis v. Sea-Land Serv., Inc., 
    688 F.2d 898
    , 906 (2d
    Cir. 1982)) (internal quotation mark omitted).
    There were no inconsistencies here, much less obvious
    ones.   Neither party has argued that the 2008 jury was confused
    when it gave its special verdict answers, or that the jury's
    indecision on causation as to the money "infected" its decision
    about the lack of violation as to housing.           Nor was that the
    rationale of the trial judge in the order on the scope of the
    retrial.
    This is also not a situation where, considering the
    totality of the circumstances, the issues were too "interwoven" to
    retry one issue separately.      See 11 Wright & Miller § 2814.        This
    case does not involve the much more common retrial issue of the
    "interwovenness" of liability and damages, see id., nor even the
    (somewhat    more   analogous)    interwovenness    of    violation    and
    causation, see, e.g., Bohack Corp. v. Iowa Beef Processors, Inc.,
    
    715 F.2d 703
    , 709 (2d Cir. 1983) (affirming district court's order
    of full retrial on Robinson-Patman Act claims after first jury
    found that defendant violated the Act but hung on whether violation
    caused plaintiff's injury).      Rather, the problem is the purported
    -80-
    interwovenness of two distinct substantive issues -- i.e., the
    hotel and the cash.
    In ordering a retrial on both of those issues, the
    district court departed from Gasoline Products Co. v. Champlin
    Refining Co., 
    283 U.S. 494
    , the very case that established the
    constitutional    propriety     of    partial     retrials.         That   case
    demonstrates that separate claims involving a shared set of facts
    can fairly be, and should be, separated on retrial.                 In Gasoline
    Products,   the   plaintiff's   claim       alleged   breach   of    a   license
    contract, and the defendant's counterclaim alleged that the license
    contract was executed in consideration for separate oral and
    written contracts that the plaintiff had breached.             
    Id. at 495-96
    .
    While the Supreme Court held that liability and damages on the
    counterclaim were too "interwoven" to retry separately, 
    id. at 500
    ,
    it did not so hold with regard to the relationship between the
    claim and counterclaim, even though a retrial on the counterclaim
    would likely have included factual allegations relating to the
    license contract.
    Similarly, in Drumgold's case, the first jury's answers
    to the special verdict questions show that the first jury was able
    to separate the two "violation" issues even though they involved a
    shared set of facts.     In other words, while it may have risked
    confusion to ask the second jury to evaluate causation on the money
    question without also evaluating violation on the money question,
    -81-
    there is no indication that a retrial jury would have been confused
    if it were asked to evaluate the entire money question without
    being allowed to reopen the hotel disclosure issue.   The presence
    of an overlapping factual background to distinct issues is not
    enough to overcome the Seventh Amendment and retry an issue already
    determined by a jury.
    If necessary in order to fairly present Drumgold's case,
    evidence as to the circumstances under which Callahan gave cash to
    Evans, including some evidence of the housing, could have been
    admitted at the second trial without having to reopen the hotel
    violation issue. The jury could have been instructed that Callahan
    had not withheld evidence about the housing and had not violated
    any rights in that regard, and that that issue was not open; any
    hotel evidence was limited to providing background.     Juries are
    often asked to accept evidence for one purpose but not another, see
    Fed. R. Evid. 105; United States v. Tse, 
    375 F.3d 148
    , 157-58 (1st
    Cir. 2004), and we presume that juries will follow the instructions
    that the district court gives them, United States v. Griffin, 
    524 F.3d 71
    , 78 (1st Cir. 2008).      Here, the district court even
    recognized this possibility, initially stating that the second
    trial could "cover the entire story [of Evans and Callahan], but
    the only question that that jury would be asked is about the
    money." Indeed, the judge followed an almost identical course with
    -82-
    regard to the use in the second trial of evidence about Tracie
    Peaks and Mary Alexander.
    The trial judge also could have avoided jury confusion by
    limiting the introduction in the second trial of certain evidence
    specifically pertaining to the hotel, on the ground that, given a
    retrial of limited scope, such evidence's probative value was
    substantially outweighed by the risk of confusing or misleading the
    jury into considering questions not before it.         See Fed. R. Evid.
    403.
    The district court's order on the scope of the retrial
    does not seriously consider these possibilities, nor explain the
    relevant    distinctions    between    the   violation   and     causation
    questions, nor point to evidence in the record supporting the
    proposition that retrying both the hotel and money issues in their
    entirety was necessary to prevent jury confusion.               The order
    explains why a causation-only retrial would be unworkable, but it
    fails to explain why that means that the hotel-violation question
    should be reopened.     The court merely states that "all aspects of
    Ricky Evans's portion of this case would be involved" in a retrial
    because    of   the   ambiguity   of   the   first   jury's    finding   of
    "substantial amounts" of money.        The order does not explain why
    this situation would make the hotel issue inextricable from the
    money issue.    See Crane, 
    731 F.2d at 1050
     ("The memorandum opinion
    of the district judge . . . casts little light on why a retrial of
    -83-
    the damages issue was thought to be necessary.").                    This was not
    merely, as    the    majority   suggests,       the    lack   of    an "extensive
    elaboration"; it was a failure to justify the basic choice at the
    heart of the district court's decision, a choice which I think
    cannot be justified.
    This outcome constitutes an abuse of discretion. In Winn
    v. Lafayette Town House, 
    839 F.2d 835
    , the appellate court reversed
    the district court's grant of a full retrial on both liability and
    damages    because   the   district     court    confused     the    relationship
    between    comparative     fault   (a   liability       issue)     and     equitable
    reduction (a damages issue) in a case under a state comparative
    negligence statute.        
    Id. at 836-37
    .         In Crane, Judge Friendly
    reversed    the   district   court's     grant    of    a   new    trial    on   both
    liability and damages because the court had not shown an adequate
    basis in the record for its determination that the jury's verdict
    on damages was tainted by an error she correctly discerned in the
    liability verdict.       
    731 F.2d at 1049-51
    .          Likewise, in this case,
    the district court abused its discretion by failing to provide a
    reasoned basis for the legal distinctions underlying its ruling on
    the scope of the retrial.
    As Judge Friendly cogently noted,
    [S]omething more is required to upset a
    verdict than the conclusory language . . .
    used by the district judge.   While we must
    guard against usurping the trial court's
    prerogative   with  respect   to   seriously
    erroneous jury verdicts, we must be equally
    -84-
    diligent in protecting the jury's function.
    Direction of a new trial on an issue
    determined by a jury without the articulation
    of a sufficient basis for such action effects
    . . . "a denigration of the jury system[,] and
    to the extent that new trials are granted the
    judge takes over, if [s]he does not usurp, the
    prime function of the jury as the trier of the
    facts."
    
    Id. at 1051
     (quoting Lind v. Schenley Indus., Inc., 
    278 F.2d 79
    , 90
    (3d Cir. 1960)).   In light of the fact that the first jury was able
    to separate the hotel and money violation questions, the district
    court's explanation for why the second jury would be unable to do
    so was inadequate to support the decision to set aside a legitimate
    jury verdict.
    The second trial should have been limited to the money
    issue only.     Since Callahan's provision of $20 to Evans was not
    material, the second jury's verdict on the money issue cannot
    support a finding of liability for Callahan.     He was entitled to
    judgment as a matter of law.
    III.
    I dissent from the majority's decision to remand this
    case for a third trial.      I would reverse the district court's
    denial of Callahan's renewed motion for judgment as a matter of law
    and its denial of qualified immunity, and order entry of judgment
    for Callahan.
    -85-