Robert Poyson v. Charles Ryan ( 2018 )


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  •                   FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    ROBERT ALLEN POYSON,                  No. 10-99005
    Petitioner-Appellant,
    D.C. No.
    v.                   2:04-cv-00534-NVW
    CHARLES L. RYAN,                   ORDER AND
    Respondent-Appellee.      AMENDED OPINION
    Appeal from the United States District Court
    for the District of Arizona
    Neil V. Wake, District Judge, Presiding
    Argued and Submitted February 15, 2012
    San Francisco, California
    Filed March 22, 2013
    Amended November 7, 2013
    Argued and Submitted En Banc September 18, 2017
    Amended January 12, 2018
    Before: Sidney R. Thomas, Chief Judge, and Raymond C.
    Fisher and Sandra S. Ikuta, Circuit Judges.
    Order;
    Opinion by Judge Fisher;
    Concurrence by Judge Ikuta
    2                        POYSON V. RYAN
    SUMMARY*
    Habeas Corpus / Death Penalty
    The panel granted a petition for panel rehearing, filed an
    amended opinion reversing the district court’s denial of
    Robert Allen Poyson’s habeas corpus petition challenging his
    death sentence, and remanded.
    The panel held that the Arizona Supreme Court denied
    Poyson his Eighth Amendment right to individualized
    sentencing by applying an unconstitutional causal nexus test
    to his mitigating evidence of a troubled childhood and mental
    health issues. The panel held that the error had substantial
    and injurious effect or influence in determining the sentence,
    and therefore granted habeas relief on this claim.
    The panel denied relief on Poyson’s claim that the
    Arizona courts failed to consider his history of substance
    abuse as a nonstatutory mitigating factor. The panel wrote
    that the state courts did consider the evidence and simply
    found it wanting as matter of fact. The panel wrote that the
    state supreme court did not misconstrue the state trial court’s
    findings, so it did not deprive Poyson of meaningful appellate
    review of his death sentence.
    The panel agreed with the district court that Poyson’s
    ineffective assistance of counsel claim is procedurally
    defaulted because it is fundamentally different from the claim
    he presented in state court.
    *
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    POYSON V. RYAN                          3
    The panel denied Poyson’s motion for reconsideration of
    its March 2013 order denying his motion for remand under
    Martinez v. Ryan, 
    566 U.S. 1
    (2012).
    Judge Ikuta concurred because the three-judge panel is
    bound by the decision in McKinney v. Ryan, 
    813 F.3d 798
    (9th Cir. 2015) (en banc), but wrote separately to highlight
    how McKinney’s erroneous conclusion that a causal nexus
    error had a “substantial and injurious effect” on a state court’s
    decision infects the panel’s decision in this case.
    COUNSEL
    Therese Michelle Day (argued), Assistant Federal Public
    Defender; Jon M. Sands, Federal Public Defender; Office of
    the Federal Public Defender, Phoenix, Arizona; for
    Petitioner-Appellant.
    J.D. Nielsen (argued) and Jon G. Anderson, Assistant
    Attorneys General; Lacey Stover Gard, Chief Counsel; Mark
    Brnovich, Attorney General; Capital Litigation Section,
    Office of the Attorney General, Phoenix, Arizona; for
    Respondent-Appellee.
    4                      POYSON V. RYAN
    ORDER
    The petition for panel rehearing filed April 12, 2013 (Dkt.
    69), which remains pending pursuant to this court’s April 2,
    2014 order (Dkt. 79), is GRANTED.
    The opinion filed November 7, 2013, and reported at
    
    743 F.3d 1183
    , is AMENDED. An amended opinion is filed
    concurrently with this order.
    No further petitions for rehearing may be filed.
    OPINION
    FISHER, Circuit Judge:
    Robert Allen Poyson was convicted of murder and
    sentenced to death in 1998. After pursuing direct review and
    seeking postconviction relief in state court, he filed a habeas
    petition in federal district court. The district court denied the
    petition, and Poyson appeals.
    Poyson raises three claims on appeal, each of which has
    been certified by the district court pursuant to Fed. R. App. P.
    22(b) and 28 U.S.C. § 2253(c): (1) the Arizona courts applied
    an unconstitutional causal nexus test to mitigating evidence;
    (2) the Arizona courts failed to consider mitigating evidence
    of his history of substance abuse; and (3) his trial counsel
    provided ineffective assistance of counsel during the penalty
    phase of his trial by failing to investigate the possibility that
    he suffered from fetal alcohol spectrum disorder. We agree
    with Poyson on his first claim. We conclude his second claim
    POYSON V. RYAN                        5
    is without merit. And we hold his third claim is procedurally
    defaulted.
    As to the first claim, we hold the Arizona Supreme Court
    denied Poyson his Eighth Amendment right to individualized
    sentencing by applying an unconstitutional causal nexus test
    to his mitigating evidence of a troubled childhood and mental
    health issues. We reach this conclusion because (1) the
    Arizona Supreme Court sentenced Poyson in 2000, which
    was in the midst of the 15-year period during which that court
    consistently applied an unconstitutional causal nexus test to
    evidence of a capital defendant’s family background or
    mental condition, see McKinney v. Ryan, 
    813 F.3d 798
    ,
    802–03 (9th Cir. 2015) (en banc); (2) in sentencing Poyson,
    the Arizona Supreme Court gave Poyson’s proffered evidence
    no weight, and it expressly did so because of the absence of
    a causal connection between the evidence and his crimes, see
    State v. Poyson, 
    7 P.3d 79
    , 90–91 (Ariz. 2000); (3) in
    affording that evidence no weight, the Arizona Supreme
    Court cited a passage in one of its earlier cases that we have
    specifically identified as articulating that court’s
    unconstitutional causal nexus test, see 
    id. (quoting State
    v.
    Brewer, 
    826 P.2d 783
    , 802 (Ariz. 1992)); 
    McKinney, 813 F.3d at 815
    ; and (4) although the Arizona Supreme Court
    couched its decision in terms of “mitigating weight” and
    “mitigating value,” our case law makes clear that the court
    deemed the evidence nonmitigating as a matter of law, see
    
    McKinney, 813 F.3d at 816
    –17. The Arizona Supreme
    Court’s application of this unconstitutional causal nexus test
    was “contrary to” the Supreme Court’s decision in Eddings
    v. Oklahoma, 
    455 U.S. 104
    (1982), see 28 U.S.C.
    § 2254(d)(1), and constituted a violation of Poyson’s rights
    under the Eighth Amendment. We further hold the error “had
    substantial and injurious effect or influence in determining”
    6                     POYSON V. RYAN
    the sentence. 
    McKinney, 813 F.3d at 822
    (quoting Brecht v.
    Abrahamson, 
    507 U.S. 619
    , 623 (1993)). We therefore grant
    habeas relief on Poyson’s causal nexus claim.
    We deny habeas relief on Poyson’s claim that the Arizona
    courts failed to consider his history of substance abuse as a
    nonstatutory mitigating factor. Poyson argues the state courts
    unconstitutionally refused to consider mitigating evidence, a
    claim arising under Lockett v. Ohio, 
    438 U.S. 586
    (1978), and
    Eddings v. Oklahoma, 
    455 U.S. 104
    (1982). The state courts,
    however, did consider the evidence. They simply found it
    wanting as a matter of fact, finding the evidence failed to
    prove a history of substance abuse. There was therefore no
    constitutional violation under Lockett and Eddings. Nor was
    there a constitutional violation under Parker v. Dugger,
    
    498 U.S. 308
    , 321 (1991). The state supreme court did not
    misconstrue the state trial court’s findings, so it did not
    deprive Poyson of meaningful appellate review of his death
    sentence.
    Finally, we agree with the district court that Poyson’s
    ineffective assistance of counsel claim is procedurally
    defaulted because it is fundamentally different from the claim
    he presented in state court. Although it is true that “new
    factual allegations do not ordinarily render a claim
    unexhausted, a petitioner may not ‘fundamentally alter the
    legal claim already considered by the state courts.’” Beaty v.
    Stewart, 
    303 F.3d 975
    , 989–90 (9th Cir. 2002) (quoting
    Vasquez v. Hillery, 
    474 U.S. 254
    , 260 (1986)). Poyson’s
    federal petition raises a theory of deficient performance –
    failure to investigate and present mitigating evidence of fetal
    alcohol spectrum disorder – that the state courts had no
    “meaningful opportunity to consider.” 
    Vasquez, 474 U.S. at 257
    . The claim is therefore procedurally defaulted.
    POYSON V. RYAN                          7
    I. BACKGROUND
    A. The Crimes
    Poyson was born in August 1976. The facts of his crimes,
    committed in 1996, were summarized as follows by the
    Arizona Supreme Court in State v. Poyson, 
    7 P.3d 79
    , 83
    (Ariz. 2000).
    Poyson met Leta Kagen, her 15 year-old son, Robert
    Delahunt, and Roland Wear in April 1996. Poyson was then
    19 years old and homeless. Kagen allowed him to stay with
    her and the others at their trailer in Golden Valley, near
    Kingman, Arizona. In August of the same year, Kagen was
    introduced to 48 year-old Frank Anderson and his 14 year-old
    girlfriend, Kimberly Lane. They, too, needed a place to live,
    and Kagen invited them to stay at the trailer.
    Anderson informed Poyson that he was eager to travel to
    Chicago, where he claimed to have organized crime
    connections. Because none of them had a way of getting to
    Chicago, Anderson, Poyson and Lane formulated a plan to
    kill Kagen, Delahunt and Wear in order to steal the latter’s
    truck.
    On the evening of August 13, 1996, Lane lured Delahunt
    into a small travel trailer on the property, ostensibly for sex.
    There, Anderson commenced an attack on the boy by slitting
    his throat with a bread knife. Poyson heard Delahunt’s
    screams and ran to the travel trailer. While Anderson held
    Delahunt down, Poyson bashed his head against the floor.
    Poyson also beat Delahunt’s head with his fists, and pounded
    it with a rock. This, however, did not kill Delahunt, so
    Poyson took the bread knife and drove it through his ear.
    8                      POYSON V. RYAN
    Although the blade penetrated Delahunt’s skull and exited
    through his nose, the wound was not fatal. Poyson thereafter
    continued to slam Delahunt’s head against the floor until
    Delahunt lost consciousness. According to the medical
    examiner, Delahunt died of massive blunt force head trauma.
    In all, the attack lasted about 45 minutes.
    After cleaning themselves up, Poyson and Anderson
    prepared to kill Kagen and Wear. They first located Wear’s
    .22 caliber rifle. Unable to find ammunition, Poyson
    borrowed two rounds from a young girl who lived next door,
    telling her that Delahunt was in the desert surrounded by
    snakes and the bullets were needed to rescue him. Poyson
    loaded the rifle and tested it for about five minutes to make
    sure it would function properly. He then stashed it near a
    shed. Later that evening, he cut the telephone line to the
    trailer so that neither of the remaining victims could call for
    help.
    After Kagen and Wear were asleep, Poyson and Anderson
    went into their bedroom. Poyson first shot Kagen in the head,
    killing her instantly. After quickly reloading the rifle, he shot
    Wear in the mouth, shattering Wear’s upper right teeth. A
    struggle ensued, during which Poyson repeatedly clubbed
    Wear in the head with the rifle. The fracas eventually moved
    outside. At some point, Anderson threw a cinder block at
    Wear, hitting him in the back and knocking him to the
    ground. While the victim was lying there, Poyson twice
    kicked him in the head. He then picked up the cinder block
    and threw it several times at Wear’s head. After Wear
    stopped moving, Poyson took his wallet and the keys to
    Wear’s truck. To conceal the body, Poyson covered it with
    debris from the yard. Poyson, Anderson and Lane then took
    POYSON V. RYAN                         9
    the truck and traveled to Illinois, where they were
    apprehended several days later.
    B. Trial and Conviction
    A grand jury indicted Poyson on three counts of first
    degree murder, one count of conspiracy to commit murder
    and one count of armed robbery. The jury convicted on all
    counts in March 1998, following a six-day trial.
    C. Sentencing
    1. Mitigation Investigation
    Following the guilty verdicts, the state trial court
    approved funds to hire a mitigation specialist to assist in
    preparing for Poyson’s sentencing. Counsel retained
    investigator Blair Abbott.
    In a June 1998 memorandum, Abbott informed counsel
    that Poyson’s mother, Ruth Garcia (Garcia), used drugs
    during the first trimester of her pregnancy and recommended
    that counsel investigate the possibility that Poyson suffered
    brain damage as a result. The memorandum advised counsel
    that “one of the significant issues should be the hard core
    drug abuse of both [of Poyson’s] parents, preconception and
    in the first trimester of Ruth’s pregnancy.” Abbott wrote that
    “Ruth Garcia’s heavy drug abuse in the pre pregnancy and
    early on in the pregnancy undoubtedly caused severe damage
    to her unborn child.”
    In September 1998, Abbott mailed trial counsel “Library
    & Internet research regarding drug & alcohol fetal cell
    damage; reflecting how these chemicals when taken in the
    10                    POYSON V. RYAN
    first trimester [a]ffect subsequent intelligence, conduct,
    emotions, urges etc [sic] as the child grows into adulthood.”
    2. Presentence Investigation Report
    The probation office prepared a presentence investigation
    report in July 1998. Poyson told the probation officer that he
    had a bad childhood because he was abused by a series of
    stepfathers, who subjected him to physical, mental and
    emotional abuse. Poyson also said he suffered from
    impulsive conduct disorder, which was diagnosed when he
    was 13. Poyson would not answer any questions on his
    substance abuse history or juvenile record.
    3. Presentencing Hearing
    In October 1998, the trial court held a one-day
    presentencing hearing. Poyson’s trial counsel called three
    witnesses to present mitigating evidence: his aunt, Laura
    Salas, his mother, Ruth Garcia, and the mitigation
    investigator, Blair Abbott. Counsel also introduced 56
    exhibits. Poyson did not testify. The witnesses testified
    about Poyson’s drug and alcohol abuse and the mental and
    physical abuse inflicted on Poyson by his stepfather,
    Guillermo Aguilar, and maternal grandmother, Mary Milner.
    They also testified that Poyson’s stepfather, Sabas Garcia
    (Sabas), committed suicide in 1988, and that Sabas’ death had
    a devastating effect on Poyson. They further testified that
    Garcia used drugs and alcohol during the first three months
    of her pregnancy with Poyson.
    POYSON V. RYAN                               11
    4. Poyson’s Sentencing Memorandum
    In early November 1998, Poyson filed a sentencing
    memorandum urging the court to find three statutory and 25
    nonstatutory mitigating circumstances.1 As relevant here,
    Poyson argued his history of drug and alcohol abuse, troubled
    childhood and personality disorders constituted both statutory
    and nonstatutory mitigating circumstances.
    a. Substance Abuse
    Poyson argued his substance abuse was a statutory
    mitigating circumstance because it impaired his capacity to
    appreciate the wrongfulness of his conduct or conform his
    conduct to the requirements of law at the time of the murders.
    See Ariz. Rev. Stat. Ann. § 13-703(G)(1) (1998). In the
    alternative, he argued that, even if his substance abuse was
    not causally related to the murders, it constituted a
    nonstatutory mitigating circumstance. In support of these
    arguments, Poyson emphasized his parents’ use of drugs and
    alcohol at the time of his conception, his mother’s use of
    drugs and alcohol during pregnancy, an incident in which
    1
    At the time of Poyson’s sentencing, Arizona law required the
    sentencing judge to impose a sentence of death if the court found one or
    more aggravating circumstances and “no mitigating circumstances
    sufficiently substantial to call for leniency.” Ariz. Rev. Stat. Ann. § 13-
    703(E) (1998). The law enumerated 10 aggravating circumstances, see 
    id. § 13-703(F),
    and five statutory mitigating circumstances – including
    diminished capacity, duress, minor participation and the defendant’s age,
    see 
    id. § 13-703(G).
    The sentencing court also was required to consider
    any nonstatutory mitigating circumstances offered by the defendant – i.e.,
    “any factors proffered by the defendant or the state which are relevant in
    determining whether to impose a sentence less than death, including any
    aspect of the defendant’s character, propensities or record and any of the
    circumstances of the offense.” 
    Id. 12 POYSON
    V. RYAN
    Poyson was involuntarily intoxicated at the age of three or
    four, Poyson’s abuse of alcohol beginning at age 13 and
    Poyson’s five-month placement at WestCare, a residential
    treatment facility, for substance abuse treatment in 1992,
    when he was 15. Poyson also pointed to evidence that he
    used PCP two days before the murders, used alcohol the night
    before the murders, used marijuana the day of the murders
    and suffered a PCP flashback during Delahunt’s murder.
    b. Troubled Childhood
    Poyson argued his troubled childhood was a statutory
    mitigating circumstance because it affected his behavior at
    the time of the murders. In the alternative, he argued his
    troubled childhood constituted a nonstatutory mitigating
    circumstance. Poyson emphasized his mother’s use of drugs
    and alcohol during the first trimester of pregnancy. He
    argued alcohol and drug use during pregnancy can cause
    brain damage and birth defects and lead a child to engage in
    delinquent and criminal behavior. He also attached to the
    sentencing memorandum several scientific articles on fetal
    alcohol syndrome. The memorandum pointed out that
    Poyson never knew his biological father, lacked a stable
    home life, was physically and mentally abused by several
    adults (including Aguilar and Milner), was devastated by
    Sabas’ suicide and was sexually abused and sodomized by a
    neighbor on one occasion shortly after Sabas’ death. Poyson
    emphasized that his delinquent behavior and substance abuse
    began shortly after the death of Sabas and the sexual assault.
    c. Mental Health Issues
    The sentencing memorandum argued Poyson suffered
    from several personality disorders, constituting a nonstatutory
    POYSON V. RYAN                       13
    mitigating circumstance. The memorandum pointed to a
    1990 psychiatric evaluation by Dr. Bruce Guernsey.
    According to the sentencing memorandum, Guernsey
    diagnosed Poyson with severe “conduct disorder,” reported
    that Poyson exhibited symptoms of antisocial behavior,
    “manic depression” or “impulsive conduct disorder” and
    recommended Poyson be prescribed medication to control his
    behavior.    Poyson also pointed to a 1990 Juvenile
    Predisposition Investigation by Nolan Barnum. Barnum too
    recommended Poyson be prescribed medication to control his
    behavior. A 1993 psychological evaluation performed by
    Jack Cordon and Ronald Jacques from the State Youth
    Services Center in St. Anthony, Idaho, diagnosed Poyson
    with “mild mood disturbance.” Dr. Celia A. Drake, who
    Poyson’s counsel retained to perform a forensic evaluation of
    Poyson, diagnosed “Adjustment Disorder with depressive
    mood, mild intensity,” and “Anti-social Personality
    Disorder.” Dr. Drake also found Poyson’s overall intellectual
    functioning to be “in the low average range.”
    5. Sentencing Hearing and Imposition of Sentence
    The state trial court held a sentencing hearing and
    imposed sentence in late November 1998.
    The court found the state had proved, beyond a reasonable
    doubt, three aggravating circumstances for the murders of
    Delahunt and Wear: the murders were committed in
    expectation of pecuniary gain; the murders were especially
    cruel; and multiple homicides committed during the same
    offense. See Ariz. Rev. Stat. Ann. § 13-703(F)(5), (6), (8)
    (1998). The court found two aggravating circumstances
    applicable to Kagen’s murder: pecuniary gain; and multiple
    homicides. See 
    id. § 13-703(F)(5),
    (8).
    14                       POYSON V. RYAN
    The court found Poyson failed to prove any statutory
    mitigating factors. Poyson’s difficult childhood and mental
    health issues were not statutory mitigating factors under § 13-
    703(G)(1) because they did not significantly impair Poyson’s
    capacity to appreciate the wrongfulness of his conduct or to
    conform his conduct to the requirements of law.2 The court
    explained:
    There has certainly been evidence that the
    defendant had gone through a turbulent life,
    perhaps had mental-health issues that would
    distinguish him from the typical person on the
    street.
    Listening to his description of how these
    murders were committed, based upon a
    description of somewhat a methodical
    carrying out of a plan, the Court sees
    absolutely nothing on the record, in this case,
    to suggest the applicability of this mitigating
    circumstance.
    Turning to nonstatutory mitigating factors, the court first
    explained the three-step analysis it used to evaluate each
    nonstatutory mitigating circumstance proffered by Poyson:
    “[1] to analyze whether the defense has shown this fact by a
    preponderance of evidence, and then if they have, [2] to
    determine whether I would assign that any weight as a
    2
    See Ariz. Rev. Stat. Ann. § 13-703(G)(1) (1998) (“Mitigating
    circumstances [include] [t]he defendant’s capacity to appreciate the
    wrongfulness of his conduct or to conform his conduct to the requirements
    of law was significantly impaired, but not so impaired as to constitute a
    defense to prosecution.”).
    POYSON V. RYAN                              15
    mitigating factor, and of course, for any that . . . pass both of
    those two tests, [3] I have to weigh them all along with the
    other factors in the final [sentencing] determination in this
    case.” The court then proceeded to consider Poyson’s mental
    health issues, troubled childhood and history of substance
    abuse as potential mitigating factors.
    a. Mental Health Issues
    The court rejected Poyson’s mental health issues as a
    nonstatutory mitigating factor at the second step in the
    analysis. The court found Poyson had proven he suffered
    from personality disorders, but gave them no weight because
    they were not causally related to the murders:
    [T]he defendant had some mental health and
    psychological issues. I think . . . the defense
    has established that there were certain . . .
    personality disorders that the defendant, in
    fact, may have been suffering from.
    The Court, however, does not find that
    they rise to the level of being a mitigating
    factor because I am unable to draw any
    connection whatsoever with such personality
    disorders and the commission of these
    offenses.3
    3
    The court rejected evidence of Poyson’s low IQ for similar reasons.
    At the first step in the analysis, the court found that “there is certain
    evidence in this case that would support the proposition that the
    defendant’s mental capacity may be diminished, at least compared to the
    norm in the population, and that his I.Q. may be low, at least compared to
    the norm in the population.” The court, however, gave this circumstance
    no mitigating weight in light of the planning and sophistication that went
    16                        POYSON V. RYAN
    b. Troubled Childhood
    The court similarly rejected Poyson’s difficult childhood
    as a nonstatutory mitigating factor. At step one, the court
    found the “defense has shown that defendant suffered a
    dysfunctional childhood, that he was subjected to physical
    and sexual abuse, and that he was subjected to certain levels
    of mental abuse.” At step two, however, the court gave these
    circumstances no mitigating weight because they were not
    causally connected to the murders: “The Court finds
    absolutely nothing in this case to suggest that his latter
    conduct was a result of his childhood.” The court also found
    “the defense has established, by a preponderance of the
    evidence, that the defendant lost a parent figure and was
    subjected to sexual abuse at a relatively young age.” The
    court rejected this factor at step two, however, because it was
    “not convinced that there is any connection between that
    abuse, that loss, and his subsequent criminal behavior.”
    c. Substance Abuse
    Finally, the court rejected Poyson’s history of substance
    abuse at both steps one and two in the analysis: Poyson failed
    to establish a significant history of drug or alcohol abuse and,
    even if he could do so, the court would have given the
    evidence no weight because he failed to establish a causal
    connection between the substance abuse and the crimes. The
    court said:
    into the crimes – “certain prep[ar]atory steps that were taken – admittedly,
    not overly-sophisticated, but attempts were made to do certain things, to
    disable warning systems to enable these murders to be committed and to
    get away with the loot that was the purpose of the murders; specifically,
    the vehicle.”
    POYSON V. RYAN                       17
    The argument is made that the defendant was
    subjected to alcohol abuse and drug abuse.
    Other than very vague allegations that he has
    used alcohol in the past or has used drugs in
    the past, other than a fairly vague assertion
    that he was subject to some sort of effect of
    drugs and/or alcohol at the time, that these
    offenses were committed, I really find very
    little to support the allegation that the
    defendant has a significant alcohol and/or
    drug abuse, and again, going back to the
    methodical steps that were taken to murder
    three people to get a vehicle to get out of
    Golden Valley, it’s very difficult for me to
    conclude that the defendant’s ability to engage
    in goal-oriented behavior was, in any way,
    impaired at the time of the commission of
    these offenses.
    Ultimately, the state trial court found only one
    nonstatutory mitigating factor – Poyson’s cooperation with
    law enforcement. The court concluded this one mitigating
    factor was insufficiently substantial to call for leniency and
    imposed a sentence of death.
    6. Arizona Supreme Court Decision
    The Arizona Supreme Court affirmed Poyson’s
    conviction and sentence on direct appeal. See State v.
    Poyson, 
    7 P.3d 79
    (Ariz. 2000). As required by Arizona law,
    the court “independently review[ed] the trial court’s findings
    of aggravation and mitigation and the propriety of the death
    sentence.” Ariz. Rev. Stat. Ann. § 13-703.01(A) (2000).
    18                    POYSON V. RYAN
    With respect to statutory mitigating factors, the supreme
    court agreed with the trial court that Poyson’s drug use was
    not a statutory mitigating circumstance under § 13-703(G)(1).
    See 
    Poyson, 7 P.3d at 88
    –89. In the court’s view, there was
    “scant evidence that he was actually intoxicated on the day of
    the murders.” 
    Id. at 88.
    “Although Poyson purportedly used
    both marijuana and PCP ‘on an as available basis’ in days
    preceding these crimes, the only substance he apparently used
    on the date in question was marijuana,” and Poyson “reported
    smoking the marijuana at least six hours before killing
    Delahunt and eleven hours before the murders of Kagen and
    Wear.” 
    Id. The evidence
    that Poyson experienced a PCP
    flashback during the murder of Delahunt was not credible,
    and even if the flashback occurred, it lasted only a “few
    moments.” 
    Id. at 88–89.
    Poyson was “not under the
    influence of PCP at any other time.” 
    Id. at 89.
    Poyson’s
    claims of substantial impairment were also belied by his
    deliberate actions, including concocting a ruse to obtain
    bullets from a neighbor, testing the rifle to make sure it would
    work properly when needed, cutting the telephone line and
    concealing the crimes. See 
    id. The court
    then turned to
    nonstatutory mitigation, agreeing with the trial court that
    Poyson’s substance abuse, mental health and abusive
    childhood were not nonstatutory mitigating circumstances.
    a. Substance Abuse
    As to substance abuse, the supreme court agreed with the
    trial court that Poyson’s evidence failed at step one because
    it did not show a history of drug or alcohol abuse:
    The trial judge refused to accord any weight
    to the defendant’s substance abuse as a
    nonstatutory mitigating circumstance. It
    POYSON V. RYAN                         19
    characterized the defendant’s claims that he
    had used drugs or alcohol in the past or was
    under the influence of drugs on the day of the
    murders as little more than “vague
    allegations.” As discussed above, we agree.
    
    Id. at 90.
    b. Mental Health Issues
    With respect to mental health issues, the supreme court
    agreed with the trial court that Poyson’s personality disorders,
    although proven at step one, were entitled to no weight at step
    two because they were not causally connected to the murders:
    The trial court found that Poyson suffers from
    “certain personality disorders” but did not
    assign any weight to this factor. Dr. Celia
    Drake diagnosed the defendant with antisocial
    personality disorder, which she attributed to
    the “chaotic environment in which he was
    raised.” She found that there was, among
    other things, no “appropriate model for moral
    reasoning within the family setting” to which
    the defendant could look for guidance.
    However, we find no indication in the record
    that “the disorder controlled [his] conduct or
    impaired his mental capacity to such a degree
    that leniency is required.” State v. Brewer,
    
    170 Ariz. 486
    , 505, 
    826 P.2d 783
    , 802 (1992);
    see also [State v. Medina, 
    193 Ariz. 504
    , 517,
    
    975 P.2d 94
    , 107 (1999)] (holding that the
    defendant’s personality disorder “ha[d] little
    or no mitigating value” where the defendant’s
    20                     POYSON V. RYAN
    desire to emulate his friends, not his mental
    disorder, was the cause of his criminal
    behavior). We therefore accord this factor no
    mitigating weight.
    
    Id. at 90–91
    (last alteration in original).
    c. Troubled Childhood
    The supreme court also agreed with the trial court’s
    assessment of Poyson’s troubled childhood. The court found
    Poyson established an abusive childhood at step one, but gave
    this consideration no weight at step two because of the
    absence of a causal nexus:
    Defendant presented some evidence that as a
    youngster he was physically and mentally
    abused by several stepfathers and his maternal
    grandmother. He also self-reported one
    instance of sexual assault by a neighbor.
    Again, however, defendant did not show that
    his traumatic childhood somehow rendered
    him unable to control his conduct. Thus, the
    evidence is without mitigating value.
    
    Id. at 91.
    Ultimately, the Arizona Supreme Court found three
    aggravating factors (pecuniary gain, murder committed in an
    especially cruel manner and multiple homicides), one
    statutory mitigating factor (Poyson’s age) and three
    nonstatutory mitigating factors (cooperation with law
    enforcement, potential for rehabilitation and family support).
    POYSON V. RYAN                               21
    See 
    id. at 90–91.4
    The court concluded the mitigating
    evidence was not sufficiently substantial to call for leniency
    and affirmed the death sentence. See 
    id. at 91–92;
    Ariz. Rev.
    Stat. Ann. § 13-703.1(B) (2000).
    D. State Postconviction Review
    The Arizona Superior Court denied Poyson’s petition for
    postconviction relief in 2003. The court provided a reasoned
    decision on Poyson’s claim of penalty phase ineffective
    assistance of counsel (his third claim in this appeal) but not
    on Poyson’s claims that the Arizona courts failed to consider
    relevant mitigating evidence (his first and second claims on
    appeal). In 2004, the Arizona Supreme Court summarily
    denied Poyson’s petition for review.
    E. Federal District Court Proceedings
    Poyson filed a federal habeas petition in 2004. In 2010,
    the district court denied the petition. The court rejected on
    the merits Poyson’s claims that the Arizona courts failed to
    consider mitigating evidence. The court also concluded
    Poyson’s penalty phase ineffective assistance of counsel
    claim was procedurally defaulted because it was
    “fundamentally different than [the claim] presented in state
    court.” Poyson timely appealed.
    4
    The Arizona Supreme Court thus found three more mitigating factors
    than the trial court found. The appellate court nonetheless agreed with the
    trial court that a death sentence was warranted.
    22                        POYSON V. RYAN
    F. Proceedings in This Court
    We originally heard argument on Poyson’s appeal in
    February 2012. We issued an opinion in March 2013, Poyson
    v. Ryan, 
    711 F.3d 1087
    (9th Cir. 2013), and an amended
    opinion in November 2013, Poyson v. Ryan, 
    743 F.3d 1185
    (9th Cir. 2013). In April 2014, we stayed proceedings on
    Poyson’s petition for panel rehearing pending the resolution
    of en banc proceedings in McKinney v. Ryan, 
    730 F.3d 903
    (9th Cir. 2013).5 Our en banc court decided McKinney in
    December 2015. See McKinney v. Ryan, 
    813 F.3d 798
    (9th
    Cir. 2015) (en banc). In May 2016, we extended the stay on
    Poyson’s petition for rehearing pending resolution of
    Supreme Court proceedings in McKinney. In October 2016,
    following the Supreme Court’s denial of the petition for writ
    of certiorari in McKinney, we further extended the stay and
    directed the parties to file supplemental briefs addressing the
    impact of McKinney on the issues presented in this appeal.
    Following the parties’ briefing, we heard oral argument on
    the petition for rehearing in September 2017. This amended
    opinion follows.
    5
    In May 2014, while our stay was in place, the Supreme Court denied
    Poyson’s petition for writ of certiorari. See Poyson v. Ryan, 
    134 S. Ct. 2302
    (2014). The Court also denied Poyson’s motion to defer
    consideration of the petition for writ of certiorari. See 
    id. The state
    contends we were required to lift our stay and issue the mandate once the
    Supreme Court denied certiorari. We disagree. Because we issued our
    stay under Fed. R. App. P. 41(d)(1), rather than Fed. R. App. P. 41(d)(2),
    the authorities upon which the state relies, including Rule 41(d)(2)(D), do
    not apply here. See Alphin v. Henson, 
    552 F.2d 1033
    , 1034–35 (4th Cir.
    1977), cited with approval by Bell v. Thompson, 
    545 U.S. 794
    , 806 (2005).
    POYSON V. RYAN                        23
    II. JURISDICTION AND STANDARD OF REVIEW
    We have jurisdiction under 28 U.S.C. §§ 1291 and
    2253(a). We review de novo the district court’s denial of
    Poyson’s petition for habeas corpus, and we review the
    district court’s findings of fact for clear error. See Brown v.
    Ornoski, 
    503 F.3d 1006
    , 1010 (9th Cir. 2007). Dismissals
    based on procedural default are reviewed de novo. See
    Robinson v. Schriro, 
    595 F.3d 1086
    , 1099 (9th Cir. 2010).
    We address Poyson’s three claims in turn.
    III. DISCUSSION
    A. Causal Nexus Test
    Poyson argues the Arizona courts applied an
    unconstitutional causal nexus test to mitigating evidence of
    his mental health issues, traumatic childhood and substance
    abuse history, in violation of his Eighth and Fourteenth
    Amendment rights to an individualized sentencing. He
    contends the state courts improperly refused to consider this
    evidence in mitigation because he failed to establish a causal
    connection between the evidence and the murders. He argues
    the state courts’ actions violate his constitutional rights as
    recognized in Tennard v. Dretke, 
    542 U.S. 274
    , 283–87
    (2004), Smith v. Texas, 
    543 U.S. 37
    , 45 (2004) (per curiam),
    and earlier decisions. These cases hold that requiring a
    defendant to prove a nexus between mitigating evidence and
    the crime is “a test we never countenanced and now have
    unequivocally rejected.” 
    Smith, 543 U.S. at 45
    .
    Because Poyson filed his federal habeas petition after
    April 24, 1996, he must not only prove a violation of these
    rights but also satisfy the Antiterrorism and Effective Death
    24                    POYSON V. RYAN
    Penalty Act of 1996 (AEDPA). See Fenenbock v. Dir. of
    Corr. for Cal., 
    681 F.3d 968
    , 973 (9th Cir. 2012).
    Under AEDPA, we may not grant habeas relief with
    respect to any claim adjudicated on the merits in state court
    unless the state court’s decision was “contrary to, or involved
    an unreasonable application of, clearly established Federal
    law, as determined by the Supreme Court of the United
    States,” or “based on an unreasonable determination of the
    facts in light of the evidence presented in the State court
    proceeding.” 28 U.S.C. § 2254(d). We review the last
    reasoned state court decision addressing the claim, which for
    Poyson’s causal nexus claim is the Arizona Supreme Court’s
    decision affirming Poyson’s death sentence on direct appeal.
    See Crittenden v. Ayers, 
    624 F.3d 943
    , 950 (9th Cir. 2010).
    Poyson relies on AEDPA’s “contrary to” prong, arguing the
    Arizona Supreme Court’s decision in State v. Poyson, 
    7 P.3d 79
    (Ariz. 2000), was contrary to Lockett v. Ohio, 
    438 U.S. 586
    (1978), Eddings v. Oklahoma, 
    455 U.S. 104
    (1982), and
    Penry v. Lynaugh, 
    492 U.S. 302
    (1989), abrogated on other
    grounds by Atkins v. Virginia, 
    536 U.S. 304
    (2002).
    1. Exhaustion
    As a threshold matter, we agree with Poyson that he has
    fully exhausted this claim. The state argues that in state court
    Poyson raised a causal nexus claim with respect to only
    mental health issues and his troubled childhood, not his
    history of substance abuse. We disagree. Having reviewed
    the record, we conclude Poyson exhausted the claim with
    respect to all three categories of mitigating evidence. See
    Powell v. Lambert, 
    357 F.3d 871
    , 874 (9th Cir. 2004) (“A
    petitioner has exhausted his federal claims when he has fully
    and fairly presented them to the state courts.”).
    POYSON V. RYAN                        25
    2. The Arizona Supreme Court’s Decision Was Contrary
    to Clearly Established Federal Law
    Lockett, Eddings and Penry held “a State could not,
    consistent with the Eighth and Fourteenth Amendments,
    prevent the sentencer from considering and giving effect to
    evidence relevant to the defendant’s background or character
    or to the circumstances of the offense that mitigate against
    imposing the death penalty.” 
    Penry, 492 U.S. at 318
    . “[I]t is
    not enough simply to allow the defendant to present
    mitigating evidence to the sentencer.” 
    Id. at 319.
    “The
    sentencer must also be able to consider and give effect to that
    evidence in imposing sentence.” 
    Id. “[T]he sentence
    imposed
    at the penalty stage should reflect a reasoned moral response
    to the defendant’s background, character, and crime.” 
    Id. (quoting California
    v. Brown, 
    479 U.S. 538
    , 545 (1987)
    (O’Connor, J., concurring)).
    Under these decisions, a state court may not treat
    mitigating evidence of a defendant’s background or character
    as “irrelevant or nonmitigating as a matter of law” merely
    because it lacks a causal connection to the crime. Towery v.
    Ryan, 
    673 F.3d 933
    , 946 (9th Cir. 2012), overruled on other
    grounds by 
    McKinney, 813 F.3d at 824
    . The sentencer may,
    however, consider “causal nexus . . . as a factor in
    determining the weight or significance of mitigating
    evidence.” Lopez v. Ryan, 
    630 F.3d 1198
    , 1204 (9th Cir.
    2011), overruled on other grounds by 
    McKinney, 813 F.3d at 818
    . “The . . . use of the nexus test in this manner is not
    unconstitutional because state courts are free to assess the
    weight to be given to particular mitigating evidence.” Schad
    v. Ryan, 
    671 F.3d 708
    , 723 (9th Cir. 2011), rev’d on other
    grounds, 
    133 S. Ct. 2548
    (2013), and overruled on other
    26                    POYSON V. RYAN
    grounds by 
    McKinney, 813 F.3d at 819
    .           As the Court
    explained in Eddings:
    Just as the State may not by statute preclude
    the sentencer from considering any mitigating
    factor, neither may the sentencer refuse to
    consider, as a matter of law, any relevant
    mitigating evidence. . . . The sentencer, and
    the Court of Criminal Appeals on review, may
    determine the weight to be given relevant
    mitigating evidence. But they may not give it
    no weight by excluding such evidence from
    their consideration.
    
    Eddings, 455 U.S. at 113
    –15.
    In 
    McKinney, 813 F.3d at 815
    , we held, “[f]or a little over
    fifteen years, the Arizona Supreme Court routinely articulated
    and insisted on [an] unconstitutional causal nexus test.”
    Under this test, “family background or a mental condition
    could be given weight as a nonstatutory mitigating factor, but
    only if defendant established a causal connection between the
    background or condition and his criminal behavior.” 
    Id. Beginning in
    1989, “[a]s a matter of law, a difficult family
    background or mental condition did not qualify as a
    nonstatutory mitigating factor unless it had a causal effect on
    the defendant’s behavior in committing the crime at issue.”
    
    Id. at 816.
    The Arizona Supreme Court “finally abandoned
    its unconstitutional causal nexus test for nonstatutory
    mitigation” in the mid-2000s. 
    Id. at 817.
    McKinney recognized that, in AEDPA cases, “we apply
    a ‘presumption that state courts know and follow the law’ and
    accordingly give state-court decisions ‘the benefit of the
    POYSON V. RYAN                        27
    doubt.’” 
    Id. at 803
    (quoting Woodford v. Visciotti, 
    537 U.S. 19
    , 24 (2002)). But that “presumption is rebutted . . . where
    we know, based on its own words, that the Arizona Supreme
    Court did not ‘know and follow’ federal law.” 
    Id. at 804.
    McKinney also recognized that “[t]he Arizona Supreme
    Court articulated the causal nexus test in various ways but
    always to the same effect.” 
    Id. at 816.
    “The Arizona Court
    frequently stated categorically that, absent a causal nexus,
    would-be nonstatutory mitigation was simply ‘not a
    mitigating circumstance.’” 
    Id. (quoting State
    v. Wallace,
    
    773 P.2d 983
    , 986 (Ariz. 1989)). “Sometimes, the court
    stated that evidence offered as nonstatutory mitigation that
    did not have a causal connection to the crime should be given
    no ‘weight.’” 
    Id. Other times,
    “the Arizona Supreme Court
    stated that evidence of a difficult family background or
    mental illness was ‘not necessarily’ or not ‘usually’
    mitigating, and then (often in the same paragraph) held as a
    matter of law that the evidence in the specific case before the
    Court was not mitigating because it had no causal connection
    to the crime.” 
    Id. at 817.
    In the case before us, we conclude the Arizona Supreme
    Court applied an unconstitutional causal nexus test to
    Poyson’s mitigating evidence of a difficult childhood and
    mental health issues. First, the court gave no weight at all to
    the evidence, and it did so because the evidence bore no
    causal connection to the crimes. See 
    Poyson, 7 P.3d at 90
    –91. With respect to Poyson’s childhood, the court ruled:
    Defendant presented some evidence that as a
    youngster he was physically and mentally
    abused by several stepfathers and his maternal
    grandmother. He also self-reported one
    28                  POYSON V. RYAN
    instance of sexual assault by a neighbor.
    Again, however, defendant did not show
    that his traumatic childhood somehow
    rendered him unable to control his
    conduct. Thus, the evidence is without
    mitigating value.
    
    Poyson, 7 P.3d at 91
    (emphasis added). With respect to
    Poyson’s mental health issues, the court ruled:
    The trial court found that Poyson suffers
    from “certain personality disorders” but did
    not assign any weight to this factor. Dr. Celia
    Drake diagnosed the defendant with antisocial
    personality disorder, which she attributed to
    the “chaotic environment in which he was
    raised.” She found that there was, among
    other things, no “appropriate model for moral
    reasoning within the family setting” to which
    the defendant could look for guidance.
    However, we find no indication in the
    record that “the disorder controlled [his]
    conduct or impaired his mental capacity to
    such a degree that leniency is required.” State
    v. Brewer, 
    170 Ariz. 486
    , 505, 
    826 P.2d 783
    ,
    802 (1992); see also 
    Medina, 193 Ariz. at 517
    , 975 P.2d at 107 (holding that the
    defendant’s personality disorder “ha[d] little
    or no mitigating value” where the defendant’s
    desire to emulate his friends, not his mental
    disorder, was the cause of his criminal
    behavior). We therefore accord this factor
    no mitigating weight.
    POYSON V. RYAN                         29
    
    Id. at 90–91
    (emphasis added) (alterations in original). This
    is some evidence that the court applied an unconstitutional
    causal nexus test in Poyson’s case. See 
    McKinney, 813 F.3d at 821
    (holding the Arizona Supreme Court applied an
    unconstitutional causal nexus test based in part on “the
    factual conclusion by the sentencing judge, which the
    Arizona Supreme Court accepted, that McKinney’s PTSD did
    not ‘in any way affect[ ] his conduct in this case’” (alteration
    in original)).
    Second, the Arizona Supreme Court affirmed Poyson’s
    death sentence in 2000, in the midst of the 15-year period
    during which that court “consistently articulated and applied
    its causal nexus test.” 
    McKinney, 813 F.3d at 803
    (emphasis
    added). Indeed, the Arizona court issued its decision in
    Poyson’s case just a few months before it decided State v.
    Hoskins, 
    14 P.3d 997
    (Ariz. 2000), supplemented, 
    65 P.3d 953
    (Ariz. 2003), a case McKinney singled out as
    exemplifying the Arizona Supreme Court’s unconstitutional
    practice. See 
    McKinney, 813 F.3d at 814
    –15. This fact
    further supports the conclusion that the Arizona Supreme
    Court applied an unconstitutional causal nexus test in
    Poyson’s case.
    Third, in applying a causal nexus test to Poyson’s mental
    health evidence, the Arizona Supreme Court cited a passage
    from State v. Brewer, 
    826 P.2d 783
    , 802 (1992), that
    McKinney specifically identified as applying an
    unconstitutional causal nexus test. Compare 
    Poyson, 7 P.3d at 90
    –91 (quoting Brewer and stating “we find no indication
    in the record that ‘the disorder controlled [his] conduct or
    impaired his mental capacity to such a degree that leniency is
    required’” (alteration in original)), with 
    McKinney, 813 F.3d at 815
    (citing this precise language in Brewer as exemplifying
    30                    POYSON V. RYAN
    the Arizona Supreme Court’s unconstitutional causal nexus
    test). This fact too supports the conclusion that the Arizona
    Supreme Court applied an unconstitutional causal nexus test
    in Poyson’s case. See 
    McKinney, 813 F.3d at 821
    (concluding the Arizona Supreme Court applied an
    unconstitutional test in part based on the court’s “pin citation
    to the precise page in [State v. Ross, 
    886 P.2d 1354
    , 1363
    (Ariz. 1994),] where it had previously articulated that test”).
    Fourth, although the Arizona Supreme Court said the
    evidence in Poyson’s case was “without mitigating value”
    and would be accorded “no mitigating weight,” suggesting
    the possibility that the court applied a causal nexus test as a
    permissible weighing mechanism, McKinney makes clear that
    the court instead applied an unconstitutional causal nexus
    test, treating the evidence as irrelevant or nonmitigating as a
    matter of law. See 
    id. at 816
    (holding the state court applied
    an unconstitutional test where “the court stated that evidence
    offered as nonstatutory mitigation that did not have a causal
    connection to the crime should be given no ‘weight’”); 
    id. (holding the
    state court applied an unconstitutional causal
    nexus test where it said “a difficult family background is not
    always entitled to great weight as a mitigating circumstance”
    (quoting State v. Towery, 
    920 P.2d 290
    , 311 (Ariz. 1996)));
    
    id. at 820
    (holding the state court applied an unconstitutional
    causal nexus test where it said “[a] difficult family
    background, including childhood abuse, does not necessarily
    have substantial mitigating weight absent a showing that it
    significantly affected or impacted a defendant’s ability to
    perceive, to comprehend, or to control his actions” (quoting
    State v. McKinney, 
    917 P.2d 1214
    , 1226 (Ariz. 1996))).
    For these reasons, we conclude the Arizona Supreme
    Court applied an unconstitutional causal nexus test to
    POYSON V. RYAN                        31
    Poyson’s evidence of a troubled childhood and mental health
    issues. “This holding was contrary to Eddings.” 
    Id. at 821.
    Accordingly, as in McKinney, we “hold that the decision of
    the Arizona Supreme Court applied a rule that was ‘contrary
    to . . . clearly established Federal law, as determined by the
    Supreme Court of the United States.’” 
    Id. (alteration in
    original) (quoting 28 U.S.C. § 2254(d)(1)).
    With respect to Poyson’s evidence of a history of
    substance abuse, however, we conclude there was no Eddings
    error. The state supreme court rejected this evidence at step
    one in the analysis, adopting the trial court’s finding as a
    matter of fact that Poyson had failed to establish a history of
    substance abuse by a preponderance of the evidence. See
    
    Poyson, 7 P.3d at 90
    . The court’s treatment of Poyson’s
    substance abuse evidence thus was not contrary to Eddings.
    3. On De Novo Review, Poyson Has Shown the Arizona
    Supreme Court Applied an Unconstitutional Causal
    Nexus Test
    Because AEDPA is satisfied, we review Poyson’s
    constitutional claim de novo. See Frantz v. Hazey, 
    533 F.3d 724
    , 735 (9th Cir. 2008) (en banc). We begin by asking
    whether Poyson has shown a constitutional violation. If
    Poyson has made this showing, we consider whether he was
    prejudiced under Brecht v. Abrahamson, 
    507 U.S. 619
    (1993).
    Poyson has satisfied the first part of this inquiry. The
    Supreme Court’s decisions in Tennard v. Dretke, 
    542 U.S. 274
    , 287 (2004), Smith v. Texas, 
    543 U.S. 37
    , 45 (2004) (per
    curiam), Lockett, Eddings and Penry all prohibit a state from
    requiring a defendant to prove a nexus between mitigating
    evidence and the crime. As discussed above, the Arizona
    32                    POYSON V. RYAN
    Supreme Court violated this rule in Poyson’s case. Poyson
    has therefore established that the Arizona Supreme Court
    applied an unconstitutional causal nexus test to evidence of
    his troubled childhood and mental health issues.
    4. Poyson Was Prejudiced
    “The harmless-error standard on habeas review provides
    that ‘relief must be granted’ if the error ‘had substantial and
    injurious effect or influence in determining the jury’s
    verdict.’” 
    McKinney, 813 F.3d at 822
    (quoting 
    Brecht, 507 U.S. at 623
    ). “There must be more than a ‘reasonable
    possibility’ that the error was harmful.” Davis v. Ayala,
    
    135 S. Ct. 2187
    , 2198 (2015) (quoting 
    Brecht, 507 U.S. at 637
    ). “[T]he court must find that the defendant was actually
    prejudiced by the error.” 
    Id. (quoting Calderon
    v. Coleman,
    
    525 U.S. 141
    , 146 (1998) (per curiam)). Under this standard:
    [I]f one cannot say, with fair assurance, after
    pondering all that happened without stripping
    the erroneous action from the whole, that the
    judgment was not substantially swayed by the
    error, it is impossible to conclude that
    substantial rights were not affected. The
    inquiry cannot be merely whether there was
    enough to support the result, apart from the
    phase affected by the error. It is rather, even
    so, whether the error itself had substantial
    influence. If so, or if one is left in grave
    doubt, the conviction cannot stand.
    
    McKinney, 813 F.3d at 822
    (alteration in original) (quoting
    Kotteakos v. United States, 
    328 U.S. 750
    , 765 (1946)).
    Accordingly, “[w]hen a federal judge in a habeas proceeding
    POYSON V. RYAN                         33
    is in grave doubt about whether a trial error of federal law had
    substantial and injurious effect or influence in determining
    the jury’s verdict, that error is not harmless. And, the
    petitioner must win.” 
    Id. (alteration in
    original) (quoting
    O’Neal v. McAninch, 
    513 U.S. 432
    , 436 (1995)).
    Our analysis once again is guided by McKinney, where
    we held the causal nexus error was prejudicial under
    circumstances similar to those presented here. See 
    id. at 822–24.
    Here, as in McKinney, there were three aggravating
    factors – pecuniary gain; especially cruel, heinous or
    depraved murders; and multiple homicides. See 
    Poyson, 7 P.3d at 87
    –88; 
    McKinney, 813 F.3d at 823
    . Here, as in
    McKinney, the improperly disregarded evidence concerned
    the defendant’s traumatic childhood and mental health issues.
    See 
    Poyson, 7 P.3d at 90
    –91; 
    McKinney, 813 P.3d at 819
    .
    As in McKinney, moreover, the evidence of a traumatic
    childhood in this case was particularly compelling. Both of
    Poyson’s parents abused drugs and alcohol at the time of his
    conception. His mother used LSD on a daily basis. She
    continued to abuse drugs and alcohol – including daily use of
    LSD – while she was pregnant with Poyson. Poyson never
    knew his biological father, an alcoholic. During his
    childhood, his mother was in relationships with many
    different men, and Poyson lacked a stable home life. One of
    these men, Guillermo Aguilar, physically and mentally
    abused Poyson, subjecting Poyson to repeated beatings.
    Aguilar brutally whipped Poyson with an electrical cord, and
    he eventually was sent to jail for abusing Poyson and his
    siblings. Others of these men abused drugs and alcohol. One
    even drank and did drugs with Poyson.
    34                    POYSON V. RYAN
    Poyson also suffered a number of physical and
    developmental problems as a child. He was developmentally
    delayed in areas such as crawling, walking and speaking. He
    had a speech impediment, fell behind in school and received
    special education services. He sustained several head
    injuries. Once, when he and his brother were playing, he had
    a stick impaled in his head. He suffered severe headaches,
    and passed out unconscious on several occasions. He was
    involuntarily intoxicated as a young child. He was subjected
    to physical abuse not only by Aguilar but also by his mother,
    who once hit him so hard it dislodged two teeth, and in
    particular by his maternal grandmother, Mary Milner, who
    beat him repeatedly and savagely.
    When Poyson was 10 or 11 years old, he suffered two
    traumatic events that, according to witnesses at Poyson’s
    sentencing, forever changed his life. Of the many adult men
    in Poyson’s life, Poyson was close with just one of them,
    Sabas Garcia, his stepfather and the one true father figure
    Poyson ever had. When Poyson was 10 or 11, however,
    Sabas committed suicide by shooting himself in the head.
    Poyson was devastated by Sabas’ death, which changed
    Poyson completely. He became distant, spending time away
    from home. He didn’t care anymore. He began using and
    abusing drugs and alcohol, and he began having behavioral
    problems. His contacts with law enforcement also began at
    this time, and his performance in school suffered
    dramatically. Before Sabas’ death, Poyson had overcome his
    earlier developmental challenges to become an A or B
    student, but after Sabas’ death he began receiving Cs, Ds and
    Fs, and he eventually dropped out of school. His family life
    became even less stable. He bounced around from relative to
    relative, living from time to time with his mother, an aunt, his
    grandmother and another stepfather. Shortly after Sabas’
    POYSON V. RYAN                        35
    death, moreover, Poyson suffered a second severe trauma in
    his life when he was lured to the home of a childhood friend
    and violently raped. The attacker threw Poyson face down on
    a bed and brutally sodomized him.
    Under the circumstances of this case, which closely track
    those in McKinney, we conclude the Arizona Supreme
    Court’s application of an unconstitutional causal nexus test
    “had a ‘substantial and injurious effect or influence’ on its
    decision to sentence [Poyson] to death.” 
    McKinney, 813 F.3d at 824
    (quoting 
    Brecht, 507 U.S. at 623
    ).
    B. Failure to Consider Substance Abuse
    At sentencing, Poyson presented evidence of a history of
    drug and alcohol abuse, but the state trial court and the state
    supreme court declined to treat the evidence as a nonstatutory
    mitigating factor. The trial court found Poyson had presented
    only “very vague allegations that he has used alcohol . . . or
    . . . drugs in the past,” and found “very little to support the
    allegation that the defendant has a significant alcohol and/or
    drug abuse” history. The supreme court agreed that Poyson’s
    claims to have “used drugs or alcohol in the past” were “little
    more than ‘vague allegations.’” 
    Poyson, 7 P.3d at 90
    .
    Poyson contends the state courts’ conclusions that he
    provided only “vague allegations” of substance abuse were
    unreasonable determinations of the facts under 28 U.S.C.
    § 2254(d)(2) and violated his constitutional rights under
    
    Lockett, 438 U.S. at 605
    , 
    Eddings, 455 U.S. at 112
    , and
    Parker v. Dugger, 
    498 U.S. 308
    , 321 (1991). We disagree.
    Poyson’s claim – that “[b]ecause his death sentence is
    based upon [an] unreasonable determination of facts, [he] is
    36                    POYSON V. RYAN
    entitled to habeas relief” – misunderstands the law. Even
    assuming that the state courts’ determination that Poyson
    provided only “vague allegations” of substance abuse was an
    unreasonable determination of the facts under § 2254(d)(2),
    an issue we need not reach, Poyson’s claim fails because he
    cannot demonstrate his constitutional rights were violated.
    See Wilson v. Corcoran, 
    562 U.S. 5
    –6 (2010) (per curiam)
    (holding that although § 2254(d)(2) relieves a federal court of
    AEDPA deference when the state court makes an
    unreasonable determination of facts, it “does not repeal the
    command of § 2254(a) that habeas relief may be afforded to
    a state prisoner ‘only on the ground’ that his custody violates
    federal law”); see also Frantz v. Hazey, 
    533 F.3d 724
    , 737
    (9th Cir. 2008) (en banc) (holding AEDPA does not “require
    any particular methodology for ordering the § 2254(d) and
    § 2254(a) determination[s]”). An unreasonable determination
    of the facts would not, standing alone, amount to a
    constitutional violation under Lockett, Eddings or Parker.
    Lockett invalidated an Ohio death penalty statute that
    precluded the sentencer from considering aspects of the
    defendant’s character or record as a mitigating factor. 
    See 438 U.S. at 604
    . Eddings held that a sentencer may not
    refuse to consider, as a matter of law, any relevant mitigating
    evidence. 
    See 455 U.S. at 113
    –15. Here, the state courts
    considered Poyson’s evidence of substance abuse, but found
    it wanting as a matter of fact and that Poyson failed to prove
    a history of substance abuse. Thus, there was no
    constitutional violation under Lockett and Eddings.
    Nor has Poyson shown a constitutional violation under
    Parker.    There, the state supreme court reweighed
    aggravating and mitigating circumstances before affirming a
    death sentence. See 
    Parker, 498 U.S. at 321
    –22. The court’s
    POYSON V. RYAN                         37
    reweighing, however, was premised on its erroneous
    assumption that the state trial court had found that there were
    no mitigating circumstances. See 
    id. The Supreme
    Court
    held the state supreme court’s action deprived the defendant
    of “meaningful appellate review,” and thus that the
    sentencing violated the defendant’s right against “the
    arbitrary or irrational imposition of the death penalty.” 
    Id. at 321.
    In Poyson’s view, Parker stands for the broad
    proposition that, “[w]hen a state court’s imposition of the
    death penalty is based not on the characteristics of the
    accused and the offense but instead on a misperception of the
    record, the defendant is not being afforded the consideration
    that the Constitution requires.” In Parker, however, the state
    supreme court had misconstrued the state trial court’s
    findings, something that did not occur here. Parker does not
    hold that a state court’s erroneous factual finding in assessing
    mitigation evidence necessarily amounts to a constitutional
    violation. Rather, it suggests the opposite:
    This is not simply an error in assessing the
    mitigating evidence.       Had the Florida
    Supreme Court conducted its own
    examination of the trial and sentencing
    hearing records and concluded that there were
    no mitigating circumstances, a different
    question would be presented. Similarly, if the
    trial judge had found no mitigating
    circumstances and the Florida Supreme Court
    had relied on that finding, our review would
    be very different.
    
    Id. at 322.
    38                    POYSON V. RYAN
    In sum, we hold Poyson is not entitled to habeas relief,
    because he has not shown a constitutional violation under
    Lockett, Eddings or Parker. Because Poyson has raised
    arguments under only Lockett, Eddings and Parker, we need
    not decide whether, or under what circumstances, a state
    court’s erroneous factfinding in assessing mitigating evidence
    can itself rise to the level of a constitutional violation.
    C. Penalty Phase Ineffective Assistance of Counsel
    In his federal habeas petition, Poyson argued he received
    ineffective assistance of counsel during the penalty phase of
    his trial because his trial counsel failed to investigate the
    possibility that he suffered from fetal alcohol spectrum
    disorder (FASD). The district court ruled Poyson failed to
    present this claim to the state courts, and hence that the claim
    was procedurally defaulted. Poyson challenges that ruling on
    appeal. We review de novo. See 
    Robinson, 595 F.3d at 1099
    .
    A state prisoner must normally exhaust available state
    judicial remedies before a federal court will entertain his
    petition for habeas corpus. See Picard v. Connor, 
    404 U.S. 270
    , 275 (1971); Weaver v. Thompson, 
    197 F.3d 359
    , 363–64
    (9th Cir. 1999); 28 U.S.C. § 2254(b)(1)(A). This rule
    “reflects a policy of federal-state comity, an accommodation
    of our federal system designed to give the State an initial
    opportunity to pass upon and correct alleged violations of its
    prisoners’ federal rights.” 
    Picard, 404 U.S. at 275
    (citations
    and internal quotation marks omitted). “A petitioner can
    satisfy the exhaustion requirement by providing the highest
    state court with a fair opportunity to consider each issue
    before presenting it to the federal court.” 
    Weaver, 197 F.3d at 364
    .
    POYSON V. RYAN                              39
    “[A] petitioner may provide further facts to support a
    claim in federal district court, so long as those facts do not
    ‘fundamentally alter the legal claim already considered by the
    state courts.’” Lopez v. Schriro, 
    491 F.3d 1029
    , 1040 (9th
    Cir. 2007) (quoting Vasquez v. Hillery, 
    474 U.S. 254
    , 260
    (1986)).6 “[T]his rule allows a petitioner who presented a
    particular [ineffective assistance of counsel] claim, for
    example that counsel was ineffective in presenting
    humanizing testimony at sentencing, to develop additional
    facts supporting that particular claim.” Moormann v. Schriro,
    
    426 F.3d 1044
    , 1056 (9th Cir. 2005) (citing 
    Weaver, 197 F.3d at 364
    ). “This does not mean, however, that a petitioner who
    presented any ineffective assistance of counsel claim below
    can later add unrelated alleged instances of counsel’s
    ineffectiveness to his claim.” 
    Id. (citing Carriger
    v. Lewis,
    
    971 F.2d 329
    , 333 (9th Cir. 1992) (en banc)).
    1. State Proceedings
    In his state habeas petition, Poyson raised two ineffective
    assistance of counsel claims relevant here. In the first claim,
    Poyson alleged trial counsel “was ineffective because he
    failed to request the appointment of experts in the field of
    mental health early in the case.” He alleged the investigation
    for both phases of the trial should have begun “immediately”
    upon counsel’s appointment, including “the immediate
    appointment of experts for both parts of the trial.” Counsel’s
    failure “to immediately secure the appointment of mental
    health experts . . . prejudiced” him in two ways. First, it
    6
    For purposes of review under 28 U.S.C. § 2254(d)(1), factual
    allegations must be based on the “record that was before the state court
    that adjudicated the claim on the merits.” Cullen v. Pinholster, 
    563 U.S. 170
    , 180 (2011).
    40                    POYSON V. RYAN
    precluded him from presenting a defense of “diminished
    capacity” with respect to the Delahunt murder during the guilt
    phase of the trial. Second, “the failure of counsel to
    immediately pursue mitigation caused the loss of mitigating
    information” that could have been presented at sentencing.
    Poyson presented a report by a neuropsychologist retained
    during the state habeas proceedings, Robert Briggs, Ph.D.
    According to Poyson, Briggs’ report showed Poyson “was
    brain-damaged” at the time of the murders, but had since
    “recovered, due to his long stay first in jail, then on
    condemned row, without chemical or physical insult to his
    brain.” In Poyson’s view, “the report leaves no doubt that
    neurophyschological testing shows that he was impaired at
    the time of the crime.” This mitigating evidence had been
    “lost forever.”
    In the state petition’s second claim, Poyson alleged trial
    counsel failed to properly present mitigation and
    psychological evidence because counsel “did nothing to show
    the trial court how [his] abusive childhood caused, or directly
    related to, [his] conduct during the murders.” He alleged trial
    counsel were deficient because they were “required to make
    some attempt to correlate Mr. Poyson’s physically and
    psychologically abusive background with his behavior,”
    because “a connection between the two would be much more
    powerful in mitigation than the abuse standing alone.”
    2. Federal Petition
    Poyson’s federal petition presented a substantially
    different claim – counsel’s failure to investigate Poyson’s
    possible fetal alcohol spectrum disorder. Poyson alleged trial
    counsel were ineffective because they “failed to make any
    effort to investigate and develop” evidence that Poyson
    POYSON V. RYAN                         41
    suffered from FASD. He alleged defense counsel “failed to
    investigate the obvious possibility that [he] suffered from
    FASD,” made “no effort” to “pursue this fertile area of
    mitigation” and “ignored obvious evidence that [he] was
    exposed to drugs and alcohol in utero.” Poyson further
    alleged he was prejudiced by counsel’s deficient
    performance:
    Their failure to adequately investigate and
    substantiate [evidence that Petitioner was
    exposed to drugs and alcohol in utero]
    profoundly prejudiced Petitioner. Adequate
    explanation during the pre-sentence hearing of
    the effect of FASD on Petitioner’s brain
    would likely have convinced the trial court
    that Petitioner had a lesser degree of
    culpability.
    3. Analysis
    The district court concluded the claim raised in the federal
    petition had not been fairly presented to the Arizona courts:
    This Court concludes that the claim asserted
    in the instant amended petition is
    fundamentally different than that presented in
    state court. Petitioner’s argument in support
    of [this claim] is based entirely on trial
    counsel’s alleged failure to investigate and
    develop mitigation evidence based on
    Petitioner’s in utero exposure to drugs and
    alcohol.     This version of Petitioner’s
    sentencing [ineffective assistance of counsel]
    claim has never been presented to the Arizona
    42                    POYSON V. RYAN
    courts. While it is true that new factual
    allegations do not ordinarily render a claim
    unexhausted, a petitioner may not
    “fundamentally alter the legal claim already
    considered by the state courts.” Beaty v.
    Stewart, 
    303 F.3d 975
    , 989–90 ([9th Cir.]
    2002) (citing 
    Vasquez, 474 U.S. at 260
    ). To
    do so deprives the state court of “a meaningful
    opportunity to consider allegations of legal
    error without interference from the federal
    judiciary.” 
    Vasquez, 474 U.S. at 257
    . Here,
    Petitioner is not simply proffering additional
    evidentiary support for a factual theory
    presented to the state court. Rather, he is
    alleging an entirely new theory of counsel
    ineffectiveness; one that has not previously
    been presented in state court.
    We agree. Poyson presented not only new facts in
    support of a claim presented to the state court, but also a
    fundamentally new theory of counsel’s ineffectiveness – one
    that the Arizona courts lacked “a meaningful opportunity to
    consider.” 
    Vasquez, 474 U.S. at 257
    . The district court
    therefore properly dismissed Poyson’s penalty phase
    ineffective assistance of counsel claim as procedurally
    defaulted.
    IV. CONCLUSION
    We reverse the district court’s judgment denying the writ
    of habeas corpus. We remand with instructions to grant the
    writ with respect to Poyson’s sentence unless the state, within
    a reasonable period, either corrects the constitutional error in
    his death sentence or vacates the sentence and imposes a
    POYSON V. RYAN                         43
    lesser sentence consistent with law. See 
    McKinney, 813 F.3d at 827
    . We do not reach Poyson’s contention, raised for the
    first time in his supplemental briefing, that he is entitled to a
    new sentencing proceeding before a jury under Ring v.
    Arizona, 
    536 U.S. 584
    (2002), Hurst v. Florida, 
    136 S. Ct. 616
    (2016), and Magwood v. Patterson, 
    561 U.S. 320
    , 332
    (2010).
    REVERSED AND REMANDED.
    ***
    Poyson’s motion for reconsideration of our March 2013
    order denying his motion for a remand under Martinez v.
    Ryan, 
    566 U.S. 1
    (2012), is without merit. Our intervening
    decision to remand in Dickens v. Ryan, 
    740 F.3d 1302
    , 1320
    (9th Cir. 2014) (en banc), did not change our holding in
    Sexton v. Cozner, 
    679 F.3d 1150
    , 1161 (9th Cir. 2012), that
    a remand is not required where, as here, the record is
    sufficiently complete for us to hold that counsel’s
    representation was not ineffective under Strickland v.
    Washington, 
    466 U.S. 668
    (1984). The additional evidence
    Poyson offers does not show remand was necessary. That Dr.
    Robert Briggs was placed on and then removed from
    probation by the Arizona Board of Psychological Examiners
    does not change our previous conclusion that Poyson’s
    postconviction relief counsel reasonably relied on Dr. Briggs,
    the retained neuropsychological expert who was aware of
    Poyson’s exposure to drugs and alcohol in utero but did not
    advise counsel that Poyson suffered from fetal alcohol
    spectrum disorder. The motion (Dkt. 74) is therefore
    DENIED.
    44                    POYSON V. RYAN
    IKUTA, Circuit Judge, concurring:
    Our en banc decision in McKinney v. Ryan, 
    813 F.3d 798
    (9th Cir. 2015) (en banc) (McKinney II), erred in concluding
    that any Eddings error had a “substantial and injurious
    effect,” 
    id. at 822
    (quoting Brecht v. Abrahamson, 
    507 U.S. 619
    , 623 (1993)), on the Arizona Supreme Court’s decision
    to affirm the defendant’s death sentence. State v. McKinney,
    
    185 Ariz. 567
    , 
    917 P.2d 1214
    (1996) (McKinney I). As a
    result, our decision today is wrongly decided. Nevertheless,
    as a three-judge panel, we are bound by McKinney II until
    either the Supreme Court or a future en banc panel overrules
    it. Therefore, I concur in the majority opinion and write
    separately only to point out how McKinney II’s error in
    applying Brecht infects our decision here.
    I
    Under AEDPA, we must determine whether the decision
    of the Arizona Supreme Court is contrary to or an
    unreasonable application of clearly established Supreme
    Court precedent. 28 U.S.C. § 2254(d)(1). It is clearly
    established that a sentencer may not “refuse to consider, as a
    matter of law, any relevant mitigating evidence.” Eddings v.
    Okla., 
    455 U.S. 104
    , 114 (1982) (italics in original); see also
    Lockett v. Ohio, 
    438 U.S. 586
    , 604 (1978). While the
    sentencer “may determine the weight to be given relevant
    mitigating evidence,” it “may not give it no weight by
    excluding such evidence from [its] consideration.” 
    Eddings, 455 U.S. at 114
    –15. Applying Lockett and Eddings, the
    Supreme Court held that a state cannot adopt a “causal nexus”
    rule, that is, a rule precluding a sentencer from considering
    mitigating evidence unless there is a causal nexus between
    that evidence and the crime. Tennard v. Dretke, 542 U.S.
    POYSON V. RYAN                         45
    274, 287 (2004). The sentencer may, however, consider
    “causal nexus . . . as a factor in determining the weight or
    significance of mitigating evidence.” Lopez v. Ryan, 
    630 F.3d 1198
    , 1204 (9th Cir. 2011) overruled on other grounds by
    McKinney 
    II, 813 F.3d at 819
    .
    In this case, the Arizona Supreme Court stated only that
    it accorded no mitigating weight to Poyson’s evidence of
    mental health and an abusive childhood. State v. Poyson, 
    198 Ariz. 70
    , 81–82 (2000). Before McKinney II, we held that
    this decision was not an unreasonable application of Lockett,
    Eddings, and Tennard because we could not presume that the
    Arizona Supreme Court had refused to consider the mental
    health and abusive childhood evidence as a matter of law.
    See Poyson v. Ryan, 
    711 F.3d 1087
    , 1090 (9th Cir. 2013).
    Rather, as instructed by the Supreme Court, we adopted the
    “presumption that state courts know and follow the law.”
    Woodford v. Visciotti, 
    537 U.S. 19
    , 24 (2002); see 
    Poyson, 711 F.3d at 1099
    .
    McKinney II flipped this presumption. It held that we
    must presume the Arizona Supreme Court applied the
    unconstitutional causal nexus test between 1989 and 2005,
    even when, as here, the court expressly discussed the weight
    of the 
    evidence. 813 F.3d at 803
    , 809, 816. This reasoning
    is contrary to Visciotti, as the McKinney II dissent made clear.
    See McKinney 
    II, 813 F.3d at 827
    –850 (Bea, J., dissenting).
    No further elaboration of this error is needed.
    II
    I write separately to highlight McKinney II’s second error:
    its conclusion that a causal nexus error has a “substantial and
    46                   POYSON V. RYAN
    injurious effect” on a state court’s 
    decision. 813 F.3d at 822
    –23.
    A
    Under Brecht, even if a state court unreasonably errs in
    applying Supreme Court precedent, a federal court may not
    provide habeas relief unless the error had a “substantial and
    injurious 
    effect.” 507 U.S. at 623
    . “There must be more than
    a ‘reasonable possibility’ that the error was harmful.” Davis
    v. Ayala, 
    135 S. Ct. 2187
    , 2198 (2015) (quoting 
    Brecht, 507 U.S. at 637
    ). Rather, a “court must find that the
    defendant was actually prejudiced by the error.” 
    Id. (quoting Calderon
    v. Coleman, 
    525 U.S. 141
    , 146 (1998) (per
    curiam)). Even an Eddings error may be harmless.
    Greenway v. Ryan, 
    866 F.3d 1094
    , 1100 (9th Cir. 2017)
    (per curiam).
    In determining that the Arizona Supreme Court’s
    presumed causal nexus error in McKinney I was prejudicial,
    McKinney II failed to provide a reasoned or reasonable
    application of Brecht. Instead, without any meaningful
    analysis, McKinney II conclusorily held that the evidence
    presumed excluded under Arizona’s presumed causal nexus
    test “would have had a substantial impact on a capital
    sentencer who was permitted to evaluate and give appropriate
    weight to it as a nonstatutory mitigating factor.” McKinney
    
    II, 813 F.3d at 823
    . Therefore, McKinney II held, the Arizona
    Supreme Court’s “application of the test had a ‘substantial
    and injurious effect or influence’ on its decision to sentence
    [the defendant] to death.” 
    Id. at 823–24
    (quoting 
    Brecht, 507 U.S. at 623
    ). In reaching this conclusion, McKinney II
    came close to enunciating a per se rule that when a state
    POYSON V. RYAN                          47
    court’s application of a causal nexus test excludes mitigating
    evidence, such an error will not be harmless.
    Such a quasi per se rule may be plausible when the
    sentencer in a particular case is a jury. If a state rule excludes
    certain mitigating evidence from the jury’s consideration as
    a matter of law, either the evidence will not be presented to
    the jury or the jury will be instructed to disregard it if they
    find no causal nexus. Because we presume a jury follows its
    instructions, Penry v. Johnson, 
    532 U.S. 782
    , 799 (2001), and
    a jury generally does not give reasons for its decision, it is
    reasonable to presume that the jury could not meaningfully
    consider even strong mitigating evidence in reaching its
    verdict if it were excluded under a causal nexus rule, see
    Abdul-Kabir v. Quarterman, 
    550 U.S. 233
    , 255 (2007). A
    court could determine that strong mitigating evidence which
    was excluded from consideration “would have had a
    substantial impact on a capital sentencer who was permitted
    to evaluate and give appropriate weight to it as a nonstatutory
    mitigating factor.”      McKinney 
    II, 813 F.3d at 823
    .
    Accordingly, in the absence of other factors (such as the
    presence of aggravating factors that “overwhelmingly
    outweighed” the mitigating evidence, see 
    Greenway, 866 F.3d at 1100
    ), an Eddings error could have a substantial and
    injurious effect.
    But the quasi per se rule adopted by McKinney II is
    entirely implausible when the sentencer is a state supreme
    court. Unlike a jury, a state supreme court has the authority
    to review and consider all the evidence in the record; this is
    particularly important, when as in Arizona, the state supreme
    court “reviews capital sentences de novo, making its own
    determination of what constitute legally relevant aggravating
    and mitigating factors, and then weighing those factors
    48                    POYSON V. RYAN
    independently.” McKinney 
    II, 813 F.3d at 819
    (citing Ariz.
    Rev. Stat. Ann. § 13-755). A state supreme court’s decision
    that certain categories of evidence are not mitigating is
    effectively the court’s conclusion that such evidence does not
    merit much weight. Just like a jury, a state supreme court can
    reasonably conclude that if a defendant’s mental impairments
    did not play a part in causing the defendant to commit a brutal
    offense, the impairments do not mitigate the defendant’s
    behavior.
    A state supreme court’s conclusion about the mitigating
    weight of various types of evidence does not have the effect
    of excluding evidence as a matter of law. Nor does such a
    conclusion preclude a state supreme court from weighing the
    evidence differently in a different case. While a jury must
    follow instructions, the state court is free to disregard its
    instructions to itself because a state supreme court may
    always revisit its precedent. As the Arizona Supreme Court
    has explained, “while we should and do pay appropriate
    homage to precedent, we also realize that we are not prisoners
    of the past.” Lowing v. Allstate Ins. Co., 
    176 Ariz. 101
    , 107
    (1993) (quoting Wiley v. The Indus. Comm’n of Ariz.,
    
    174 Ariz. 94
    , 103 (1993)). Indeed, even McKinney II
    acknowledged that by the mid-2000s, the Arizona Supreme
    Court had stopped applying the precedent that McKinney II
    presumed compelled the use of a causal nexus 
    test. 813 F.3d at 817
    .
    Finally, unlike a jury, a state supreme court generally
    explains its reasons, and so may articulate its conclusion that
    defendant’s impairments merited little or no mitigating
    weight. See 
    Greenway, 866 F.3d at 1100
    . Where a state
    supreme court has reached a reasoned conclusion that
    aggravating circumstances outweigh mitigating evidence in
    POYSON V. RYAN                          49
    a particular case, there does not seem to be a reasonable
    possibility that the state supreme court would reach a
    different result merely because a federal court announces that
    the state court has secretly maintained an unconstitutional
    causal nexus rule all along. See 
    id. B Because
    McKinney II failed to distinguish between a state
    supreme court and a jury, its Brecht analysis fails.
    In McKinney I, the Arizona Supreme Court explained that
    it “conducts a thorough and independent review of the record
    and of the aggravating and mitigating evidence to determine
    whether the sentence is justified, . . . consider[ing] the quality
    and strength, not simply the number, of aggravating or
    mitigating factors.” 185 Ariz at 578. In its opinion, the
    Arizona Supreme Court reviewed the defendant’s evidence of
    childhood abuse and post-traumatic stress disorder (PTSD).
    
    Id. at 587.
    It determined that the judge had fully considered
    evidence from several witnesses that defendant had “endured
    a terrible childhood,” as well as the PTSD diagnosis. 
    Id. But the
    court held that “a difficult family background, including
    childhood abuse, does not necessarily have substantial
    mitigating weight absent a showing that it significantly
    affected or impacted the defendant’s ability to perceive,
    comprehend, or control his actions.” 
    Id. After considering
    the defendant’s abusive childhood and its impact on his
    behavior and ability to conform his conduct, the Arizona
    Supreme Court found there was no error in determining that
    the evidence of childhood abuse was “insufficiently
    mitigating to call for leniency.” 
    Id. 50 POYSON
    V. RYAN
    In light of the Arizona Supreme Court’s reasoned
    consideration and weighing of the mitigating evidence, there
    was no basis for concluding that this same evidence would
    have a different impact – let alone a substantial impact – on
    the same court on resentencing simply because a federal court
    provides a reminder that Eddings precludes a sentencer from
    applying the causal nexus rule. McKinney 
    II, 813 F.3d at 823
    –24. Brecht does not permit “mere speculation” about the
    potential prejudice to a defendant. 
    Davis, 135 S. Ct. at 2198
    (quoting 
    Calderon 525 U.S. at 146
    ). Because there is not a
    reasonable possibility that the presumed legal error
    influenced the Arizona Supreme Court, or have more than a
    slight effect, the sentence should stand. See Kotteakos v.
    United States, 
    328 U.S. 750
    , 764 (1946); 
    Davis, 135 S. Ct. at 2198
    . McKinney II erred in ruling otherwise.
    III
    Because we are bound by McKinney II’s erroneous
    application of Brecht, its error infects this appeal as well. In
    our case, the Arizona Supreme Court considered Poyson’s
    mitigating evidence regarding his mental health and abusive
    childhood, but stated merely that it accorded these factors “no
    mitigating weight.” 
    Poyson, 198 Ariz. at 81
    –82. On the
    other hand, the Arizona Supreme Court found that the
    evidence supported aggravating circumstances of
    (1) pecuniary gain, (2) especially cruel, heinous, or depraved
    murder, and (3) multiple homicide. Id at 78–79. Based on its
    findings, the court upheld Poyson’s death sentence. Id at 82.
    The court did so while performing its duty to “independently
    review and reweigh the aggravating and mitigating
    circumstances in every capital case . . . .” 
    Id. at 81.
                         POYSON V. RYAN                        51
    Here, the Arizona Supreme Court reviewed and
    considered Poyson’s mitigating evidence, and balanced it
    against the case’s aggravating circumstances. Accordingly,
    there is no basis for concluding that our correction of any
    presumed Eddings error “would have had a substantial impact
    on a capital sentencer who was permitted to evaluate and give
    appropriate weight to it as a nonstatutory mitigating factor.”
    McKinney 
    II, 813 F.3d at 823
    . We should therefore conclude
    that any presumed causal nexus error was not prejudicial, and
    therefore Poyson is not entitled to relief.
    Because we are bound by McKinney II (at least for the
    time being), we are unable to reach this correct conclusion.
    As a result, I reluctantly concur in the majority opinion.