Smith v. Chrisman , 824 F.3d 1233 ( 2016 )


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  •                                                                                   FILED
    United States Court of Appeals
    PUBLISH                                Tenth Circuit
    UNITED STATES COURT OF APPEALS                           June 6, 2016
    Elisabeth A. Shumaker
    FOR THE TENTH CIRCUIT                              Clerk of Court
    _________________________________
    MICHAEL DEWAYNE SMITH,
    Petitioner - Appellant,
    v.                                                           No. 14-6201
    KEVIN DUCKWORTH, Interim Warden,
    Oklahoma State Penitentiary,
    Respondent - Appellee.
    _________________________________
    Appeal from the United States District Court
    for the Western District of Oklahoma
    (D.C. No. 5:09-CV-00293-D)
    _________________________________
    Emma V. Rolls, Assistant Public Defender (Patti Palmer Ghezzi, Assistant Federal Public
    Defender, with her on the briefs), Office of the Public Defender, Oklahoma City,
    Oklahoma, for Petitioner-Appellant.
    Thomas Lee Tucker (E. Scott Pruitt, Attorney General of Oklahoma, and Robert
    Whittaker, Assistant Attorney General on the brief), Office of the Attorney General for
    the State of Oklahoma, Oklahoma City, Oklahoma, for Respondent-Appellee.
    _________________________________
    Before BRISCOE, HOLMES, and McHUGH, Circuit Judges.
    _________________________________
    McHUGH, Circuit Judge.
    _________________________________
    
    Pursuant to Fed. R. App. P. 43(c)(2), Kevin Duckworth, who was appointed
    Interim Warden of the Oklahoma State Penitentiary on May 9, 2016, is automatically
    substituted for Anita Trammell as Respondent in this case.
    I.   INTRODUCTION
    Michael DeWayne Smith was charged with two counts of murder for the
    killings of Sarath Pulluru and Janet Moore. He was convicted and sentenced to death.
    The Oklahoma Court of Criminal Appeals affirmed his convictions on direct appeal
    and denied his two applications for postconviction relief. Mr. Smith sought a writ of
    habeas corpus in federal district court, arguing, as relevant here, that he is ineligible
    for the death penalty because he is intellectually disabled, that the state trial court had
    erred in admitting Mr. Smith’s videotaped confession to the murders at trial, that his
    trial counsel had rendered ineffective assistance in the presentation of his mitigation
    case, and that cumulative error rendered his trial unfair.1 The district court denied
    habeas relief, and Mr. Smith appealed.
    We granted Mr. Smith’s request for a certificate of appealability on these four
    issues, and we now affirm the district court’s judgment. Mr. Smith has failed to
    demonstrate that the Oklahoma Court of Criminal Appeals’ rejection of his claims
    was contrary to or involved an unreasonable application of clearly established federal
    law. Thus, applying the deferential standard mandated by the Antiterrorism and
    Effective Death Penalty Act, we affirm the district court’s denial of habeas relief.
    1
    Because the scope of our review is limited to the four issues on which we
    granted a certificate of appealability, we do not discuss other claims Mr. Smith raised
    in the state proceedings or in the district court.
    2
    II.   BACKGROUND
    A. Factual Background 2
    Petitioner Michael DeWayne Smith is a member of the Oak Grove Posse
    (OGP), a subset of the Crips gang that operates in Oklahoma City. In November
    2000, Teron “T-Nok” Armstrong and two other members of the OGP attempted to
    rob Tran’s Food Mart in south Oklahoma City. The store owner shot and killed Mr.
    Armstrong. Mr. Smith was not involved in the robbery but had “close personal ties”
    to Mr. Armstrong. Smith v. State (Smith I), 
    157 P.3d 1155
    , 1161 (Okla. Crim. App.
    2007).
    The other two would-be robbers were later arrested and were set to be tried for
    the robbery in February 2002. Two days before the trial, Mr. Smith, armed with a
    .357 revolver, went to the apartment of Janet Moore. Believing Ms. Moore’s son was
    a police informant, Mr. Smith kicked in her door and confronted her. When she
    began to scream, Mr. Smith shot her to death. Before leaving, Mr. Smith wiped down
    the apartment to eliminate any fingerprint evidence.
    Mr. Smith next went to the A-Z Mart, a convenience store “immediately next
    door” to Tran’s Food Mart—the site of the earlier failed robbery attempt. 
    Id. at 1161.
    Mr. Smith “emptied two pistols into” the clerk on duty, Sarath Pulluru, took money
    2
    This summary of the facts is based principally on the Oklahoma Court of
    Criminal Appeals’ recitation of the facts in Mr. Smith’s direct appeal. See generally
    Smith v. State (Smith I), 
    157 P.3d 1155
    (Okla. Crim. App. 2007). We presume a state
    court’s factual findings to be correct unless the petitioner rebuts that presumption by
    “clear and convincing evidence.” 28 U.S.C. § 2254(e)(1). Mr. Smith has not done so
    here.
    3
    from the register, and then used lighter fluid to set fires around the store. 
    Id. He set
    fire to Mr. Pulluru’s body and “whatever he had touched in the A-Z Mart to destroy
    evidence.” 
    Id. at 1162.
    Afterward he disposed of the clothes he had worn during the
    murders.
    Mr. Smith returned home early the next morning and reported to his roommate
    that he had killed Janet Moore, had “done something else to ‘take care of business,’”
    and had “avenged his family.” 
    Id. at 1161.
    A couple of hours later, Mr. Smith went to
    the home of Sheena Johnson. He told her that he had killed Ms. Moore because her
    son had been “snitching” and that he had “killed a person at a ‘chink’ store” because
    someone connected to the A-Z Mart “had been on television ‘dissing’ his set” in
    response to the earlier attempted robbery. 
    Id. Ms. Johnson
    later reported this
    conversation to police, who had already taken Mr. Smith into custody on a different
    matter.
    Three days after Mr. Smith was arrested, detectives interviewed him about the
    killings. He signed a written waiver of his Miranda rights3 and agreed to talk to the
    detectives. After initially denying his involvement, Mr. Smith admitted to both
    murders, explaining that he “killed both victims in retaliation for wrongs done him or
    his family.” 
    Id. He explained
    that he went to Ms. Moore’s apartment looking for her
    son but ended up killing her when she “panicked and started screaming.” 
    Id. And he
    3
    Under Miranda v. Arizona, a suspect in custody must be informed of his
    rights to refuse to answer questions or to have retained or appointed counsel present
    during questioning. 
    384 U.S. 436
    , 445 (1966).
    4
    stated that he killed Mr. Pulluru “in retaliation against the store owner who shot
    Armstrong and in retaliation for disrespectful comments about Armstrong in the press
    attributed to someone from the A-Z Mart.” 
    Id. He further
    admitted that he had
    disposed of the clothes he wore during the murders, wiped down Ms. Moore’s
    apartment to eliminate fingerprints, and set fires in the A-Z Mart to destroy evidence.
    Mr. Smith’s confession was videotaped.
    B. Procedural Background
    1. Trial and Direct Appeal
    The State of Oklahoma charged Mr. Smith with two counts of murder,
    burglary, robbery with a firearm, and arson. The state trial court held a pretrial
    hearing to determine the validity of Mr. Smith’s Miranda waiver and the
    admissibility of Mr. Smith’s videotaped confession. At the hearing, Mr. Smith put on
    evidence that he was “a long term PCP user” and admitted to being under the
    influence of PCP at the time of his arrest. 
    Id. at 1171.
    An expert witness testified for
    the defense and opined that Mr. Smith could have still been under the influence of
    PCP at the time of his interrogation conducted three days after his arrest. Mr. Smith
    also sought to elicit testimony regarding his low intelligence and information
    processing deficits from Dr. Faust Bianco, a neuropsychologist. Mr. Smith proffered
    Dr. Bianco’s opinion that Mr. Smith’s “functioning at a borderline or low average
    [IQ] range with deficiencies in the information processing speed and the influence of
    the chronic and current PCP use would affect his ability to understand the Miranda
    5
    warnings and more importantly to understand the consequences of waiving those
    warnings.”
    The trial court rejected the offer of proof, stating that “there are many indicia[]
    demonstrat[ing] that this Defendant possessed intelligence” and “demonstrated in
    many different ways his understanding of what was going on.” The trial court
    reasoned that “testimony regarding [Mr. Smith’s] specific IQ range would [not] be
    relevant” and excluded Dr. Bianco’s testimony. Relying on its own observations of
    Mr. Smith’s demeanor over the course of the two-hour recorded interview, the trial
    court concluded that Mr. Smith had knowingly and voluntarily waived his Miranda
    rights and that his videotaped confession was therefore admissible.
    The case proceeded to trial, and the jury returned a guilty verdict on all five
    counts. In the penalty phase for Mr. Smith’s murder convictions, the State sought to
    prove two aggravating circumstances: (1) that “each murder was especially heinous,
    atrocious or cruel,” and (2) that “there existed a probability that Smith would commit
    future acts of violence constituting a continuing threat to society.” 
    Id. at 1160
    & n.1.
    Defense counsel presented a mitigation defense centered on Mr. Smith’s inability to
    cope with his father’s death, leading to his increased involvement with gangs. The
    jury found both aggravating circumstances for each killing and fixed Mr. Smith’s
    punishment as death for each count. The trial court accordingly sentenced Mr. Smith
    to death.
    Mr. Smith appealed, arguing his waiver of Miranda rights was invalid because
    the trial court refused to receive evidence of his low intelligence in evaluating the
    6
    validity of that waiver. The Oklahoma Court of Criminal Appeals (the OCCA)
    rejected that claim and affirmed Mr. Smith’s conviction and sentence on direct
    appeal. 
    Id. at 1171–72,
    1180. Mr. Smith petitioned the United States Supreme Court
    for a writ of certiorari, which the Court denied. Smith v. Oklahoma, 
    552 U.S. 1191
    (2008).
    2. Postconviction Proceedings
    Mr. Smith next filed his first Application for Post-Conviction Relief with the
    OCCA. He argued that his trial counsel rendered ineffective assistance in the penalty
    phase by failing to fully investigate and present evidence of his family and social
    history, including evidence of harsh discipline or physical abuse, early and consistent
    exposure to drugs, and childhood head injuries. The OCCA denied relief in an
    unpublished order.
    Mr. Smith then petitioned the federal district court for a writ of habeas corpus
    under 28 U.S.C. § 2254. In that petition, Mr. Smith argued he was intellectually
    disabled and therefore ineligible for the death penalty under Atkins v. Virginia,4 the
    OCCA had unreasonably determined that his Miranda waiver was valid, and his trial
    counsel had rendered ineffective assistance in the mitigation phase by failing to
    present evidence of his troubled upbringing, intellectual disability, and substance
    abuse. With his habeas petition pending in federal court, Mr. Smith filed a second
    4
    As discussed in more detail below, the Supreme Court held in Atkins v.
    Virginia that execution of intellectually disabled defendants violates the Eighth
    Amendment’s bar on cruel and unusual punishment. 
    536 U.S. 304
    , 321 (2002).
    7
    Application for Post-Conviction Relief with the OCCA, seeking to exhaust his Atkins
    claim and his ineffective-assistance claim based on failure to present intellectual-
    disability and substance-abuse evidence. The OCCA denied this second application
    in a published decision, Smith v. State (Smith II), 
    245 P.3d 1233
    (Okla. Crim. App.
    2010).
    Mr. Smith then returned to federal court and sought adjudication of his habeas
    petition. The district court denied relief, ruling that Mr. Smith was not intellectually
    disabled and had not shown the OCCA’s decisions with respect to his Miranda
    waiver or ineffective-assistance claim were contrary to or an unreasonable
    application of clearly established federal law. The district court denied a certificate of
    appealability (COA) on all issues.
    Mr. Smith then sought a COA from this court, which we granted on four
    issues: Mr. Smith’s intellectual-disability claim, his challenge to the exclusion of Dr.
    Bianco’s testimony concerning the validity of his Miranda waiver, his claim of
    ineffective assistance of counsel in the penalty phase, and cumulative error.
    III. DISCUSSION
    Federal habeas corpus review of a state prisoner’s conviction and sentence is
    circumscribed by the provisions of the Antiterrorism and Effective Death Penalty Act
    of 1996 (AEDPA). Under AEDPA, a habeas petitioner is not entitled to relief on a
    claim that has been adjudicated in state court unless “the state court’s resolution of
    his claims was ‘contrary to, or involved an unreasonable application of, clearly
    established Federal law, as determined by the Supreme Court of the United States’ or
    8
    ‘was based on an unreasonable determination of the facts in light of the evidence
    presented in the State court proceeding.’” Hooks v. Workman, 
    689 F.3d 1148
    , 1163
    (10th Cir. 2012) (quoting 28 U.S.C. § 2254(d)(1), (2)). AEDPA thus “erects a
    formidable barrier to federal habeas relief for prisoners whose claims have been
    adjudicated in state court” and “requires a state prisoner [to] show that the state
    court’s ruling on the claim being presented in federal court was so lacking in
    justification that there was an error . . . beyond any possibility for fairminded
    disagreement.” Burt v. Titlow, 
    134 S. Ct. 10
    , 16 (2013) (alteration and omission in
    original) (internal quotation marks omitted). But if “some fairminded jurists could
    possibly agree with the state court decision, then it was not unreasonable and the writ
    should be denied.” Frost v. Pryor, 
    749 F.3d 1212
    , 1225 (10th Cir. 2014).
    A state-court decision is contrary to clearly established federal law under 28
    U.S.C. § 2254(d)(1) if it “applies a rule that contradicts the governing law set forth in
    Supreme Court cases or confronts a set of facts that are materially indistinguishable
    from a decision of the Supreme Court and nevertheless arrives at a result different
    from that precedent.” Ryder ex rel. Ryder v. Warrior, 
    810 F.3d 724
    , 739 (10th Cir.
    2016) (internal quotation marks omitted). “A state-court decision is an ‘unreasonable
    application’ of Supreme Court precedent if the decision ‘correctly identifies the
    governing legal rule but applies it unreasonably to the facts of a particular prisoner’s
    case.’” Fairchild v. Trammell, 
    784 F.3d 702
    , 711 (10th Cir. 2015) (quoting Williams
    v. Taylor, 
    529 U.S. 362
    , 407–08 (2000)). In analyzing a state-court decision’s
    compliance with clearly established federal law, we measure the decision against “the
    9
    governing legal principle or principles set forth by the Supreme Court at the time the
    state court renders its decision.” Lockyer v. Andrade, 
    538 U.S. 63
    , 71–72 (2003).
    That inquiry focuses exclusively on “the holdings, as opposed to the dicta, of [the
    Supreme Court’s] decisions as of the time of the relevant state-court decision.” 
    Id. at 71
    (internal quotation marks omitted). “The absence of clearly established federal
    law is dispositive under § 2254(d)(1).” 
    Hooks, 689 F.3d at 1163
    .
    Review of a state court’s factual findings under § 2254(d)(2) is similarly
    narrow. We will not conclude a state court’s factual findings are unreasonable
    “merely because we would have reached a different conclusion in the first instance.”
    Brumfield v. Cain, 
    135 S. Ct. 2269
    , 2277 (2015) (brackets omitted). Rather, we must
    defer to the state court’s factual determinations so long as “reasonable minds
    reviewing the record might disagree about the finding in question.” 
    Id. Accordingly, a
    state court’s factual findings are presumed correct, and the petitioner bears the
    burden of rebutting that presumption by “clear and convincing evidence.” 28 U.S.C.
    § 2254(e)(1). But if the petitioner can show that “the state courts plainly
    misapprehend[ed] or misstate[d] the record in making their findings, and the
    misapprehension goes to a material factual issue that is central to petitioner’s claim,
    that misapprehension can fatally undermine the fact-finding process, rendering the
    resulting factual finding unreasonable.” 
    Ryder, 810 F.3d at 739
    (internal quotation
    marks omitted).
    In determining whether the federal district court erred in denying habeas relief,
    “we review the district court’s legal analysis of the state court decision de novo and
    10
    its factual findings, if any, for clear error.” 
    Frost, 749 F.3d at 1223
    (internal
    quotation marks omitted). Our review is limited to the record that was before the
    state court that adjudicated the claim on the merits. 
    Id. at 1224.
    A. Intellectual-Disability Claim
    We first address Mr. Smith’s claim that he is intellectually disabled and that
    the OCCA’s rejection of his intellectual-disability claim is contrary to or an
    unreasonable application of Atkins. The OCCA determined this claim was
    procedurally barred but evaluated the merits to determine if ineffective assistance of
    counsel excused the procedural default. We therefore consider both the OCCA’s
    procedural-bar and merits rulings.
    1. Procedural Bar
    Mr. Smith raised his intellectual-disability claim for the first time in his second
    Application for Post-Conviction Relief before the OCCA. The OCCA concluded the
    claim was procedurally defaulted because it was not raised on direct appeal, in Mr.
    Smith’s first Application for Post-Conviction Relief, or within sixty days of its
    discovery. Smith II, 
    245 P.3d 1233
    , 1236 (Okla. Crim. App. 2010). But the OCCA
    evaluated the merits of the claim to determine whether Mr. Smith’s postconviction
    counsel had rendered ineffective assistance that would excuse the procedural default.5
    5
    The OCCA evaluated the performance of Mr. Smith’s postconviction counsel
    based on Mr. Smith’s argument that postconviction counsel had the first opportunity
    to raise this claim because his trial counsel also served as appellate counsel. Smith II,
    
    245 P.3d 1233
    , 1236 (Okla. Crim. App. 2010). The OCCA assumed for purposes of
    11
    Finding the underlying claim of intellectual disability without merit, the OCCA
    determined that postconviction counsel had not rendered ineffective assistance and
    that the substantive issue was waived for failure to timely raise it. 
    Id. at 1237–38.
    Mr.
    Smith raises three separate challenges to the application of Oklahoma’s procedural
    bar to this claim, but we need not address those challenges because we elect to
    proceed directly to the merits.
    Federal habeas review is generally barred where the prisoner “defaulted his
    federal claims in state court pursuant to an independent and adequate state procedural
    rule,” unless the prisoner can demonstrate cause for the default and “actual
    prejudice” resulting from the alleged violation. Thacker v. Workman, 
    678 F.3d 820
    ,
    835 (10th Cir. 2012). However, where “the claim may be disposed of in a
    straightforward fashion on substantive grounds,” this court retains discretion to
    bypass the procedural bar and reject the claim on the merits. Revilla v. Gibson, 
    283 F.3d 1203
    , 1210–11 (10th Cir. 2002). Because we conclude this claim is readily
    resolved on the merits, we elect to bypass the procedural issues.
    2. Merits
    The OCCA evaluated the merits of this claim and our review is therefore
    governed by AEDPA.6 As a result, we may not grant relief unless Mr. Smith
    its analysis that Mr. Smith’s failure to raise the issue earlier was excused because he
    was represented by the same counsel at trial and on direct appeal. 
    Id. 6 Mr.
    Smith contends that because the OCCA concluded this claim was
    procedurally barred, its analysis of the claim under the ineffective-assistance rubric
    does not constitute an adjudication on the merits that would subject its decision to
    12
    demonstrates the OCCA’s decision is contrary to or an unreasonable application of
    clearly established federal law. 
    Fairchild, 784 F.3d at 711
    . Mr. Smith contends the
    OCCA’s rejection of his intellectual-disability claim is contrary to Atkins v. Virginia,
    
    536 U.S. 304
    (2002), because the OCCA’s evaluation of his claim is “inconsistent
    with clinical practices.”
    a. Atkins and Intellectual Disability
    In Atkins, the Supreme Court held that the Eighth Amendment’s prohibition on
    “cruel and unusual punishments” forbids the execution of intellectually disabled
    criminal 
    defendants. 536 U.S. at 321
    . But the Supreme Court declined to “provide
    definitive procedural or substantive guides for determining when a person who
    claims [intellectual disability] will be so impaired” as to be ineligible for the death
    penalty. Bobby v. Bies, 
    556 U.S. 825
    , 831 (2009) (internal quotation marks omitted).
    Rather, recognizing that “serious disagreement” could exist regarding who should be
    deemed so intellectually disabled as to be categorically excluded from execution, the
    Court “le[ft] to the State[s] the task of developing appropriate ways to enforce the
    AEDPA deference. But we have held that “[w]hen a state court analyzes appellate
    counsel ineffectiveness as an excuse for procedural default, we must afford AEDPA
    deference to that analysis.” Ryder ex rel. Ryder v. Warrior, 
    810 F.3d 724
    , 746 (10th
    Cir. 2016). The OCCA’s analysis of postconviction counsel’s performance as an
    excuse for procedural default is no less an adjudication of the merits than the same
    inquiry undertaken with respect to appellate counsel’s performance. Accordingly,
    because the OCCA considered the merits of Mr. Smith’s intellectual-disability claim
    in considering whether ineffective assistance excused his procedural default, we must
    apply AEDPA deference to the OCCA’s evaluation of that claim.
    13
    constitutional restriction.” 
    Atkins, 536 U.S. at 317
    (second alteration in original)
    (quoting Ford v. Wainwright, 
    477 U.S. 399
    , 405, 416–17 (1986)).
    The Court in Atkins did, however, base its analysis on clinical definitions of
    intellectual disability, and the Court has since recognized that such definitions “were
    a fundamental premise of Atkins.” Hall v. Florida, 
    134 S. Ct. 1986
    , 1999 (2014). In
    particular, the Court noted that “clinical definitions of mental retardation require not
    only subaverage intellectual functioning, but also significant limitations in adaptive
    skills such as communication, self-care, and self-direction that became manifest
    before age 18.” 
    Atkins, 536 U.S. at 318
    . And the Court observed that “an IQ between
    70 and 75 or lower” is “typically considered the cutoff IQ score for the intellectual
    function prong of the mental retardation definition.” 
    Id. at 309
    n.5. Most states have
    responded to the Court’s decision in Atkins by incorporating clinical definitions of
    intellectual disability into their death-penalty frameworks.
    A clinical diagnosis of intellectual disability generally requires “an IQ score
    that is approximately two standard deviations below the mean, considering the
    standard error of measurement for the specific instruments used.” American
    Association on Intellectual and Developmental Disabilities, Intellectual Disability:
    Definition, Classification, and Systems of Supports 31 (11th ed. 2010). The mean
    score for a standardized IQ test is 100, and the standard deviation is approximately
    15. 
    Hall, 134 S. Ct. at 1994
    . “Thus a test taker who performs two or more standard
    deviations from the mean will score approximately 30 points below the mean on an
    IQ test, i.e., a score of approximately 70 points.” 
    Id. 14 Every
    IQ test has a “standard error of measurement,” or SEM, that reflects
    inherent imprecision in the test. 
    Id. at 1995.
    The generally accepted SEM adjustment
    for assessing intellectual disability is plus or minus five points of IQ, or
    approximately two times the typical SEM for an IQ test. Id.; accord American
    Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders 37
    (5th ed. 2013) [DSM-5]. “On tests with a standard deviation of 15 and a mean of 100,
    this involves a score of 65–75 (70 +/- 5).” DSM-5 at 37; accord 
    Atkins, 536 U.S. at 309
    n.5.
    Central to Mr. Smith’s challenge is a theory known as the Flynn Effect, which
    proposes that the mean IQ score of a population increases at a rate of approximately
    0.3 points per year. Hooks v. Workman, 
    689 F.3d 1148
    , 1169 (10th Cir. 2012). Under
    this theory, the result of an IQ test must be adjusted to account for how long ago the
    test was “normed,” or compared to a representative population at that time. In theory,
    because the mean IQ goes up over time, a test normed years before it is given will
    return an inflated score relative to the current mean IQ of the population—the
    yardstick against which intellectual disability is measured. Accordingly, proponents
    of the Flynn Effect argue IQ scores must be adjusted downward by 0.3 points for
    each year that has passed since the test was normed to arrive at a proper measure of
    the test taker’s IQ. 
    Id. Scientific and
    legal acceptance of this theory is mixed. 
    Id. at 1170.
    15
    b. Oklahoma’s Intellectual-Disability Statute
    Oklahoma prohibits by statute the execution of a defendant who has
    established intellectual disability by proving three elements: “significantly
    subaverage general intellectual functioning, significant limitations in adaptive
    functioning, and that the onset of the mental retardation was manifested before the
    age of eighteen (18) years.” Okla. Stat. tit. 21, § 701.10b(C). The statute further
    provides that an “intelligence quotient of seventy (70) or below on an individually
    administered, scientifically recognized standardized intelligence quotient test
    administered by a licensed psychiatrist or psychologist is evidence of significantly
    subaverage general intellectual functioning.” 
    Id. The statute’s
    reference to IQ as a
    touchstone for determining general intellectual function comes with two important
    qualifications: first, “[i]n determining the intelligence quotient, the standard
    measurement of error for the test administrated shall be taken into account.” 
    Id. Second, “in
    no event shall a defendant who has received an intelligence quotient of
    seventy-six (76) or above on any individually administered, scientifically recognized,
    standardized intelligence quotient test administered by a licensed psychiatrist or
    psychologist, be considered mentally retarded.” 
    Id. c. Mr.
    Smith’s Challenge
    In support of his intellectual-disability claim, Mr. Smith offered the results of
    three IQ tests indicating IQ scores of 76, 79, and 71. He contended that these scores,
    once adjusted for the SEM and Flynn Effect, all fall below 70—within the typical
    range of intellectual disability. The OCCA rejected this argument, concluding first
    16
    that the Flynn Effect “is not a relevant consideration in the mental retardation
    determination for capital defendants.” Smith 
    II, 245 P.3d at 1237
    n.6. The OCCA
    went on to conclude that Mr. Smith’s scores of 76 or higher disqualified him from a
    finding of intellectual disability. The OCCA held the 76 cutoff was not subject to
    adjustment for the SEM because “the Legislature has implicitly determined that any
    scores of 76 or above are in a range whose lower error-adjusted limit will always be
    above the threshold score of 70.” 
    Id. at 1237.
    Because section 701.10b of the
    Oklahoma Statutes provides that a score 76 or higher on any IQ test bars a defendant
    from being found intellectually disabled, the OCCA concluded Mr. Smith’s
    intellectual-disability claim failed under the express language of the statute. 
    Id. Mr. Smith
    argues that “Oklahoma’s rigid IQ score cut-off” is contrary to and
    an unreasonable application of Atkins. Although Mr. Smith couches this argument
    broadly in terms of the Oklahoma law’s failure to comport with clinical practices in
    evaluating intellectual-disability claims, the only clinical practices he identifies as
    relevant to our inquiry are adjustment for the SEM and the Flynn Effect.
    With respect to the SEM, Atkins itself does not discuss the concept of the
    SEM, and nothing in that decision mandates adjustment of IQ scores to account for
    inherent testing error. Rather, the Supreme Court first held in Hall v. Florida that the
    SEM must be accounted for in evaluating an Atkins intellectual-disability claim. 
    134 S. Ct. 1986
    , 2001 (2014). As discussed above, our review of the OCCA’s decision is
    normally limited to evaluating whether that decision was contrary to or unreasonably
    applied the holdings of the Supreme Court in force at the time it was rendered.
    17
    Lockyer v. Andrade, 
    538 U.S. 63
    , 71–72 (2003). Because Hall was decided more than
    three years after the OCCA ruled against Mr. Smith on this issue, Hall provides no
    basis for us to disturb the OCCA’s decision.
    But even assuming for purposes of argument that we could consider Hall’s
    holding here, section 701.10b of the Oklahoma Statutes explicitly directs courts to
    take into account “the standard measurement of error for the test administered” in
    determining if a defendant has met the “threshold requirement” of an IQ score of 70
    or below. Smith 
    II, 245 P.3d at 1237
    . And as the OCCA explained in Smith II, the
    Oklahoma legislature implicitly incorporated the SEM into the IQ cutoff of 76 by
    excluding from the reach of the statute those defendants whose SEM-adjusted IQ
    score would remain above the threshold score of 70. 
    Id. That is,
    a score of 76
    adjusted downward by 5 to account for the SEM equals 71 and therefore results in an
    adjusted score that falls outside the intellectual-disability threshold of 70. Because
    the statute’s cutoff score excludes only those whose SEM-adjusted IQ score would
    fall outside the generally accepted range for intellectual disability, Oklahoma’s
    statutory regime accounts for the SEM as required by Hall. Thus, even if subsequent
    Supreme Court authority is considered, Mr. Smith has failed to demonstrate the
    OCCA’s decision is contrary to or an unreasonable application of Hall due to a
    failure to account for the SEM.
    Mr. Smith’s remaining challenge can therefore be distilled to a claim that the
    OCCA unreasonably refused to apply the Flynn Effect in considering the evidence of
    18
    his IQ.7 His core contention is that “Oklahoma’s strict construction of the
    intellectual-functioning element as a bright-line cutoff, with no adjustment for
    obsolete norms of outdated IQ tests, misunderstands and distorts the use of IQ
    scores.” And Mr. Smith criticizes “Oklahoma’s failure to adjust an IQ score for norm
    obsolescence,” contending that his IQ test results were “inflated as a result of the
    growing obsolescence of the tests themselves.” As discussed, the adjustment for
    “obsolete norms” is known as the Flynn Effect and proposes a 0.3 point reduction in
    a test taker’s IQ score for every year since the test was “normed” by comparing it to a
    representative population.
    This argument, however, squarely contradicts our ruling in Hooks v. Workman,
    where we explained that Oklahoma’s failure to apply the Flynn Effect was not
    contrary to or an unreasonable application of clearly established federal law in light
    of 
    Atkins. 689 F.3d at 1170
    . We concluded in Hooks that the threshold requirement of
    clearly established federal law had not been met, because Atkins does not mandate an
    adjustment for the Flynn Effect, federal and state courts are divided on the validity of
    applying the Flynn Effect in an Atkins claim, and “no decision of the Supreme Court
    squarely addresses the issue.” 
    Id. at 1170
    (brackets and ellipses omitted).
    7
    While Mr. Smith observes generally that, under Oklahoma law, “defendants
    who have just one IQ score above 75 always fall outside of Atkins’ protection,
    regardless of . . . the existence of other scores below 75,” he raises no specific
    challenge to this aspect of the law beyond his Flynn Effect claim and has not
    otherwise attempted to demonstrate that such a rule is contrary to federal law.
    19
    Mr. Smith contends that our holding in Hooks is “no longer tenable” in light of
    Hall, which he argues “made clear that clinical practices must be followed” in
    evaluating an Atkins claim. Again leaving aside whether Mr. Smith can rely on
    Hall—a decision issued more than three years after the OCCA ruled against him—
    Hall says nothing about application of the Flynn Effect to IQ scores in evaluating a
    defendant’s intellectual disability. Rather, Hall focuses exclusively on the “statistical
    fact” of the SEM for a given IQ test and holds that the SEM must be considered in
    evaluating intellectual-disability 
    claims. 134 S. Ct. at 1995
    . Because our review
    under AEDPA is limited to “the holdings, as opposed to the dicta” of the Supreme
    Court’s decisions, 
    Lockyer, 538 U.S. at 71
    , Hall provides no basis for us to depart
    from our conclusion in Hooks.8 And Mr. Smith has identified no other Supreme Court
    case that has addressed the Flynn Effect at all, let alone mandated its consideration in
    evaluating intellectual-disability claims under Atkins. Hooks therefore controls our
    resolution of this issue.
    Mr. Smith has failed to show that the OCCA’s refusal to apply the Flynn
    Effect to his IQ scores was contrary to or an unreasonable application of clearly
    established federal law. We therefore affirm the district court’s denial of habeas
    relief on Mr. Smith’s intellectual-disability claim.
    8
    Neither can Hall be read as more broadly prohibiting the application of
    Oklahoma’s IQ cutoff score of 76. In Hall, the Supreme Court invalidated Florida’s
    “strict IQ test score cutoff of 70” for intellectual-disability claims. Hall v. Florida,
    
    134 S. Ct. 1986
    , 1994 (2014). But the Court expressly excluded from its analysis “the
    rule in States which use a bright-line cutoff at 75 or greater” because the petitioner
    had not challenged the higher IQ cutoff. 
    Id. at 1996.
    20
    B. Miranda Waiver
    Mr. Smith next argues the OCCA’s rejection of his Miranda claim was
    unreasonable because the trial court and the OCCA failed to properly apply the
    “totality of the circumstances” standard in assessing the validity of his Miranda
    waiver. Specifically, Mr. Smith argues the OCCA “flouted and unreasonably” applied
    this standard when it agreed with the trial court that Dr. Bianco’s testimony regarding
    clinical testing of Mr. Smith’s intellectual capacity was not relevant to the validity of
    his Miranda waiver. Because the OCCA addressed this claim on the merits on direct
    appeal, we may not grant relief unless Mr. Smith demonstrates the OCCA’s decision
    is contrary to or an unreasonable application of clearly established federal law.
    Fairchild v. Trammell, 
    784 F.3d 702
    , 711 (10th Cir. 2015).
    Miranda v. Arizona holds that the Fifth Amendment guarantees a suspect in
    custody the right to refuse questioning or to have retained or appointed counsel
    present during questioning. 
    384 U.S. 436
    , 444–45 (1966). A defendant may waive
    these rights, but any such waiver must be made “voluntarily, knowingly and
    intelligently.” 
    Id. at 444.
    To determine if a defendant has validly waived his Miranda
    rights, the trial court must engage in two distinct inquiries:
    First, the relinquishment of the right must have been voluntary in the sense
    that it was the product of a free and deliberate choice rather than
    intimidation, coercion, or deception. Second, the waiver must have been
    made with a full awareness of both the nature of the right being abandoned
    and the consequences of the decision to abandon it. Only if the “totality of
    the circumstances surrounding the interrogation” reveal both an uncoerced
    choice and the requisite level of comprehension may a court properly
    conclude that the Miranda rights have been waived.
    21
    Moran v. Burbine, 
    475 U.S. 412
    , 421 (1986) (quoting Fare v. Michael C., 
    442 U.S. 707
    ,
    725 (1979)). “The totality approach permits—indeed, it mandates—inquiry into all the
    circumstances surrounding the interrogation.” 
    Fare, 442 U.S. at 725
    . These
    circumstances include “evaluation of the [suspect’s] age, experience, education,
    background, and intelligence, and . . . whether he has the capacity to understand the
    warnings given him, the nature of his Fifth Amendment rights, and the consequences of
    waiving those rights.” 
    Id. But mental
    deficiency alone does not render a Miranda waiver
    invalid. Colorado v. Connelly, 
    479 U.S. 157
    , 164 (1986).
    Mr. Smith argued on direct appeal that the trial court “failed to properly
    evaluate the validity of the Miranda waiver under the totality of the circumstances
    standard” because the trial court “refused to allow a neuropsychologist, Dr. Bianco,
    to testify at the suppression hearing as to [Mr. Smith’s] intelligence.” Smith I, 
    157 P.3d 1155
    , 1171 (Okla. Crim. App. 2007). Mr. Smith contended “Dr. Bianco’s
    testimony was necessary to establish that [Mr. Smith] was of low intelligence and as
    a result was unable to comprehend the nature or consequences of the rights he was
    waiving.” 
    Id. The OCCA
    rejected this argument, concluding the trial court had not
    abused its discretion in rejecting the proposed testimony as irrelevant to the Miranda
    inquiry. 
    Id. at 1171–72.
    And the OCCA held that the trial court had “sufficient
    evidence before [it] to find by a preponderance of evidence that Smith knowingly and
    voluntarily waived his Miranda rights.” 
    Id. Mr. Smith
    argues that his intellectual capacity is relevant to whether he could
    offer a knowing and intelligent waiver of his Miranda rights, and the OCCA’s
    22
    decision therefore “flies in the face of Moran, Edwards[ v. Arizona, 
    451 U.S. 477
    (1981)], and [Fare v.] Michael C.” He contends Dr. Bianco could have provided
    relevant testimony regarding Mr. Smith’s IQ, academic skills, reading ability, and the
    potential effect of his chronic PCP use on his ability to understand the waiver of his
    Miranda rights. Because the trial court rejected this testimony, Mr. Smith contends it
    failed to properly consider his low intelligence in the totality of the circumstances
    analysis, and he argues the OCCA’s approval of that decision was therefore contrary
    to clearly established federal law.
    But Mr. Smith’s narrow focus on Dr. Bianco’s clinical opinion ignores the trial
    court’s broader consideration of Mr. Smith’s intelligence in evaluating the validity of
    his Miranda waiver. After defense counsel offered Dr. Bianco’s testimony that Mr.
    Smith is “borderline to low intelligence” and was “very slow in processing
    information,” the trial court gave a detailed explanation of its findings that Mr. Smith
    had sufficiently understood the waiver of his Miranda rights. Based on its review of
    Mr. Smith’s videotaped interview, the trial court observed that Mr. Smith was “very
    cocky” and “extremely verbal about how he tricks people and misleads them and has
    got them convinced how crazy he is”; that he “was able to plan how to switch clothes
    with different people and conceal his identity” to hide from police; that during the
    interview he was not “disoriented or unable to comprehend” but rather was
    “extremely animated and disturbingly explanatory about the murders he committed
    and how they were other people’s fault”; and that he demonstrated the “ability to
    reason, make intelligent decisions, to co-op other people into his plan and to
    23
    understand perfectly the consequences of his actions as he’s trying to avoid capture.”
    Ultimately, the trial court determined that “there are many indicia[] demonstrat[ing]
    that [Mr. Smith] possessed intelligence” and that, during the interview, “he
    demonstrated in many different ways his understanding of what was going on.”
    Accordingly, the trial court concluded that “testimony regarding his specific IQ
    range” would not be relevant to its assessment of his Miranda waiver.
    The trial court’s findings demonstrate that it gave fair consideration to Mr.
    Smith’s intelligence with respect to his ability to understand the nature of the rights
    he was waiving and the consequences of his waiver. The trial court’s findings
    regarding Mr. Smith’s intelligence are based on the court’s own observations of Mr.
    Smith’s behavior and interactions with the detectives over the course of a nearly two-
    hour interview, and Mr. Smith has not rebutted the correctness of these findings. See
    Ryder ex rel. Ryder v. Warrior, 
    810 F.3d 724
    , 739 (10th Cir. 2016). Neither has Mr.
    Smith identified Supreme Court precedent establishing that a trial court must, when
    evaluating the knowing and voluntary nature of a Miranda waiver, assess a
    defendant’s intelligence through expert testimony concerning the defendant’s IQ
    score or other clinical measures of intellectual ability rather than the trial court’s own
    observations of the defendant.
    Instead, Mr. Smith seizes on a statement by the trial court, viewed in isolation,
    to suggest it failed to consider Mr. Smith’s intelligence in assessing his Miranda
    waiver. In response to counsel’s explanation that Dr. Bianco would testify as to his
    24
    clinical testing of Mr. Smith’s intelligence, the trial court questioned whether that
    testimony was relevant:
    Now, the fact that he’s [of] low intelligence I don’t think is a huge surprise
    to anybody based on the fact that we all deal with criminal law and most of
    the Defendants who come in here are not rocket scientists. Is there any law
    that says that I am to take that into consideration in Jackson v. Denno?
    Even someone of low intelligence.
    Mr. Smith believes this statement demonstrates “the trial court did not believe the law
    required her to consider Mr. Smith’s low intelligence as part of the inquiry as to whether
    Mr. Smith knowingly and intelligently waived his Miranda rights.” But this claim cannot
    be squared with the trial court’s detailed discussion of Mr. Smith’s intelligence and its
    reasons for finding his Miranda waiver voluntary. A more plausible interpretation is that
    the trial court was questioning whether it was obligated to consider expert testimony
    concerning clinical evidence of Mr. Smith’s specific IQ. Indeed, the trial court’s findings
    demonstrate a proper and thorough consideration of Mr. Smith’s intelligence in assessing
    whether he voluntarily, knowingly, and intelligently waived his Miranda rights. Thus,
    Mr. Smith has not demonstrated that the OCCA’s approval of the trial court’s ruling was
    unreasonable in light of clearly established federal law, and we affirm the district court’s
    denial of habeas relief on this claim.
    C. Ineffective Assistance in Penalty Phase
    Mr. Smith also argues that his trial counsel rendered ineffective assistance in
    the investigation and presentation of mitigating evidence in the penalty phase of his
    trial. Mr. Smith contends the mitigation case put on by defense counsel was
    inadequate and failed to humanize Mr. Smith. Specifically, he claims trial counsel
    25
    should have instead presented evidence of his low intelligence and his troubled
    childhood—including evidence of physical and sexual abuse, early and continuous
    drug use, and childhood head injuries. The OCCA addressed these claims on the
    merits, and its rulings are therefore subject to deferential review under AEDPA.
    Hooks v. Workman, 
    689 F.3d 1148
    , 1163 (10th Cir. 2012).
    To establish ineffective assistance of counsel, a defendant must show both that
    counsel’s performance was deficient and that the defense was prejudiced by that
    deficient performance. Strickland v. Washington, 
    466 U.S. 668
    , 687 (1984). An
    insufficient showing on either element is fatal to an ineffective-assistance claim,
    rendering consideration of the other element unnecessary. 
    Id. at 697.
    To demonstrate
    deficient performance, “the defendant must show that counsel’s representation fell
    below an objective standard of reasonableness” when evaluated from counsel’s
    perspective at the time. 
    Id. at 688.
    “The question is whether an attorney’s
    representation amounted to incompetence under prevailing professional norms, not
    whether it deviated from best practices or most common custom.” Harrington v.
    Richter, 
    562 U.S. 86
    , 105 (2011). And to establish prejudice, the defendant must
    show that, but for counsel’s deficient performance, there is a reasonable probability
    the result of the proceeding would have been different. 
    Strickland, 466 U.S. at 694
    .
    Because imposition of the death sentence under Oklahoma law requires a unanimous
    jury, Malone v. State, 
    168 P.3d 185
    , 215 n.138 (Okla. Crim. App. 2007), “the
    question is whether there is a reasonable probability that, absent the errors, [at least
    26
    one juror] . . . would have concluded that the balance of aggravating and mitigating
    circumstances did not warrant death.” 
    Strickland, 466 U.S. at 695
    .
    Although presented as a single claim, Mr. Smith’s argument challenges two
    separate rulings by the OCCA. In his first Application for Post-Conviction Relief,
    Mr. Smith argued that trial counsel was ineffective for failing to pursue a
    “‘reasonable’ investigation into Mr. Smith’s family and social history.” He submitted
    evidence showing he was delivered by forceps and born with a swollen area on his
    head, his father was an abusive alcoholic, he grew up in a crime-ridden neighborhood
    surrounded by gangs, he struggled with school work, and he got involved in gangs at
    a young age. The OCCA rejected this claim, finding no prejudice when viewing the
    record as a whole because this new evidence was largely cumulative with the
    evidence presented at trial and “the slight bit of new information contained in these
    materials is tenuous at best.” In his second Application for Post-Conviction Relief,
    Mr. Smith argued trial counsel was ineffective for failure to present evidence that,
    due to organic brain damage and the long-term effects of his PCP abuse, Mr. Smith
    had low intelligence and limited mental abilities. The OCCA rejected this claim on
    prejudice grounds as well, concluding the evidence had a “double-edged quality”
    because “such evidence might bolster a conclusion that the defendant represents a
    continuing threat to society.” Smith II, 
    245 P.3d 1233
    , 1242–43 (Okla. Crim. App.
    2010). We address the OCCA’s rulings in turn.
    27
    1. Family and Social History
    Mr. Smith contends the OCCA’s rejection of the ineffective-assistance claim
    in his first Application for Post-Conviction Relief was based on an unreasonable
    determination of the facts.9 We will not conclude that a state court’s determination of
    the facts is unreasonable unless the court plainly and materially misstated the record
    or the petitioner shows that reasonable minds could not disagree that the finding was
    in error. Ryder ex rel. Ryder v. Warrior, 
    810 F.3d 724
    , 739 (10th Cir. 2016).
    In support of his first Application for Post-Conviction Relief, Mr. Smith
    submitted affidavits from family members recounting details of Mr. Smith’s
    childhood: that his father and other family members imposed harsh physical
    discipline or abuse; that his father was an alcoholic and abusive toward his mother
    until his parents separated when Mr. Smith was approximately two years old; that
    Mr. Smith was introduced to drugs and gangs at a young age by his brothers; that Mr.
    Smith was born with a swollen area on his head, was delivered by forceps, and
    suffered other head injuries as a child; and that Mr. Smith was sexually abused by an
    older woman when he was seven or eight years old. Mr. Smith also attached a
    protective order his mother had obtained against his father, in which she stated that
    Mr. Smith’s father was “very violent” and had threatened “to kill and to fight” her.
    In rejecting Mr. Smith’s claim, the OCCA stated the “affidavits and documents
    establish a larger quantity of mitigating evidence than was presented at trial, but
    9
    Mr. Smith has presented no argument that the OCCA’s ruling on this point
    was contrary to or an unreasonable application of clearly established federal law.
    28
    cover little new ground.” The OCCA observed that the evidence tended to show
    “Smith’s father was an alcoholic, that he was abusive, . . . that Smith was a gang
    member,” and “that Smith grew up in a neighborhood known for gang activity,
    violence, and drug activity.” In the OCCA’s view, this information had, “in one form
    or another,” already been developed at trial. The OCCA also noted Mr. Smith had
    failed to connect the evidence of childhood head injuries to any then-current medical
    diagnoses of brain damage, intellectual disability, or other impairment.10 And the
    OCCA concluded that the “slight bit of new information” was “tenuous at best.” The
    OCCA therefore concluded that, “when the materials are viewed as a whole,” there
    was no reasonable probability the outcome of Mr. Smith’s sentencing would have
    been different. Accordingly, the OCCA rejected Mr. Smith’s ineffective-assistance
    claim on prejudice grounds without evaluating trial counsel’s performance.
    Mr. Smith argues the OCCA’s factual determinations are unreasonable for two
    reasons. First, he challenges as “patently unreasonable” the OCCA’s conclusion that
    the relevant information had been developed at trial and that the postconviction
    materials therefore “cover[ed] little new ground.” While Mr. Smith concedes the jury
    heard evidence of his father’s “criminal behavior” and “Mr. Smith’s exposure to
    gangs through older brothers,” he contends the jury never heard about the “sexual
    10
    At the time the OCCA ruled on this claim, Mr. Smith had yet to present to
    the OCCA the opinion of Dr. Saint Martin, who diagnosed Mr. Smith with
    intellectual disability and opined that his intellectually disability could have been
    caused, in part, by “genetics or intrauterine developmental problems” that a
    childhood head injury “could have worsened.”
    29
    and physical abuse Mr. Smith suffered as a child,” the head injuries Mr. Smith
    experienced, or “the extent of the violence perpetrated” by his father against his
    mother.
    But even if the OCCA mischaracterized the specific contours of the evidence
    that had been placed before the jury, and even assuming for purposes of our analysis
    that the OCCA’s factual error was unreasonable, Mr. Smith has failed to demonstrate
    that error entitles him to habeas relief. Under § 2254(d)(2), “an unreasonable
    determination of the facts does not, itself, necessitate relief.” Byrd v. Workman, 
    645 F.3d 1159
    , 1172 (10th Cir. 2011) (internal quotation marks omitted). Rather, a habeas
    petitioner must demonstrate that the state court’s decision is “based on”—i.e., “rests
    upon”—that unreasonable determination of the facts. 
    Id. Mr. Smith
    has failed to make the necessary showing with respect to the
    OCCA’s analysis of prejudice under Strickland. In pressing this argument, Mr. Smith
    makes no real attempt to explain how this purported factual error undermined the
    OCCA’s Strickland analysis. Rather, he merely asserts that, had the jury been
    presented with additional mitigation evidence, “there is a reasonable probability at
    least one [juror] would have arrived at a sentence less than death.” But that claim
    illustrates only that Mr. Smith disagrees with the OCCA’s ultimate determination that
    he suffered no prejudice; it says nothing about whether the OCCA’s prejudice
    decision was “based on” an erroneous factual finding.
    Mr. Smith’s failure to explain the relationship between the alleged error and
    the OCCA’s analysis is fatal when considering the prejudice standard the OCCA was
    30
    required to apply. In evaluating whether prejudice resulted from the omission of
    mitigation evidence, the OCCA was obligated to consider the totality of mitigation
    evidence before it—both that adduced at trial and that adduced in the postconviction
    proceeding—and to reweigh the combined mitigation evidence against the
    aggravation evidence presented by the state. Williams v. Taylor, 
    529 U.S. 362
    , 397–
    98 (2000). The OCCA was then required to consider whether, in light of the old and
    new evidence taken together, a reasonable likelihood existed that one or more jurors
    would have voted against the death penalty. 
    Strickland, 466 U.S. at 695
    . Mr. Smith
    has made no attempt to explain how the OCCA’s alleged misunderstanding of
    whether certain evidence had been first presented at trial or in Mr. Smith’s
    Application for Post-Conviction Relief affected its analysis of whether the totality of
    the mitigation evidence gave rise to a reasonable probability of a non-death verdict.
    Moreover, the OCCA stated that its prejudice determination was based on a review of
    the evidentiary materials as a whole, and Mr. Smith does not argue the OCCA failed
    to properly apply the correct standard. Accordingly, Mr. Smith has failed to
    demonstrate that the OCCA’s prejudice decision was “based on an unreasonable
    determination of the facts.” 28 U.S.C. § 2254(d)(2) (emphasis added).
    Second, Mr. Smith challenges the OCCA’s characterization of the evidence
    presented in support of his first Application for Post-Conviction Relief as “slight,”
    and “tenuous at best.” He asserts this characterization is unreasonable because it fails
    to recognize the relevance of a disadvantaged background to the issue of moral
    culpability. However, the OCCA’s characterization of the evidence as “slight” and
    31
    “tenuous” is a matter of weight, not relevance. Mr. Smith’s argument thus advances
    nothing more than his disagreement with the weight afforded to this evidence by the
    OCCA. But neither his disagreement, nor even this court’s disagreement, can render
    a state court’s weighing of the evidence unreasonable. Brumfield v. Cain, 
    135 S. Ct. 2269
    , 2277 (2015). Rather, Mr. Smith was required to show that “reasonable minds
    reviewing the record” could not disagree that the OCCA’s determination that he had
    not been prejudiced by counsel’s performance was erroneous. 
    Id. (internal quotation
    marks omitted). He has not undertaken to do so and, based on our review of the
    record, we conclude that reasonable minds could differ on this point. We must
    therefore defer to the OCCA’s evaluation of the evidence presented in Mr. Smith’s
    first Application for Post-Conviction Relief.
    Mr. Smith has failed to demonstrate the OCCA unreasonably concluded he
    was not prejudiced by trial counsel’s failure to present the omitted family- and social-
    history evidence in mitigation. Because the OCCA reasonably concluded that Mr.
    Smith suffered no prejudice, we do not consider whether trial counsel rendered
    deficient performance by failing to present this evidence. We therefore affirm the
    district court’s denial of habeas relief on this aspect of Mr. Smith’s ineffective-
    assistance claim.
    2. Low Intelligence and Drug Use
    We next consider Mr. Smith’s challenge to the OCCA’s rejection of the
    claim—raised in his second Application for Post-Conviction Relief—that his trial
    counsel was ineffective for failure to present evidence of his low intelligence due to
    32
    organic brain damage and long-term PCP use. He contends the OCCA’s
    determination that no prejudice stemmed from the omission of this “double-edged”
    evidence is contrary to Sears v. Upton, 
    561 U.S. 945
    (2010). We will conclude a
    state-court decision is contrary to governing federal law only if it applies a
    contradictory rule or confronts a set of facts materially indistinguishable from
    Supreme Court precedent and arrives at a different result. 
    Ryder, 810 F.3d at 739
    .
    In his second Application for Post-Conviction Relief, Mr. Smith argued that
    trial counsel was “ineffective for failing to provide Mr. Smith’s jury with evidence
    that he suffers from organic brain damage and low intelligence” because “[t]rial
    counsel failed to investigate the long term effects of phencyclidine (PCP) use and
    abuse.” “If counsel had done this investigation,” Mr. Smith contended, “they could
    have presented powerful mitigation evidence to the jury.” In support of this claim,
    Mr. Smith relied on reports from Drs. Manuel Saint Martin and Deborah Mash, who
    both opined that Mr. Smith’s long-term use of PCP likely contributed to brain
    damage and lowered intelligence. Mr. Smith specifically quoted Dr. Saint Martin’s
    conclusions regarding the effect of drug use on his developing brain:
    [T]he clinical picture for Mr. Smith is . . . childhood/adolescent brain insult
    caused by substance abuse.
    ....
    The substances linked to neural damage in Mr. Smith’s developing brain
    are PCP, alcohol and marijuana. PCP is known to produce dissociative
    states and symptoms similar to schizophrenia. Long term use of PCP is
    neurotoxic in rat and primate brains, and in humans it inhibits the brain’s
    ability to learn new information.
    ....
    33
    The tests indicate non-specific brain damage affecting his attention,
    calculation, and short term memory. These . . . neuropsychological deficits
    could be due to Mr. Smith’s substance use, especially PCP . . . .
    (Alteration and omissions in original.) Mr. Smith also quoted Dr. Mash’s opinion that
    “[t]he early exposure to PCP and [Mr. Smith’s] chronic use contributed to diffuse
    impairment of cognitive functioning” and “Mr. Smith’s [early] exposure [and chronic
    use of] ‘wet’ undoubtedly contributed to developmental brain abnormalities . . . .”11
    (Alterations and omission in original.)
    The OCCA rejected Mr. Smith’s ineffective-assistance claim. Limiting its
    analysis to prejudice, the OCCA concluded this evidence has a “double-edged
    quality,” and noted that a “a jury presented with evidence that the defendant is a
    chronic substance abuser might draw a negative inference from that evidence just as
    easily as it might find it mitigating.” Smith 
    II, 245 P.3d at 1242
    –43. The OCCA also
    noted, in the context of Mr. Smith’s case, “such evidence might bolster a conclusion
    that the defendant represents a continuing threat to society, one of the aggravating
    circumstances charged.” 
    Id. at 1243.
    The OCCA accordingly concluded that Mr.
    Smith failed to demonstrate “a reasonable probability that the jury would have
    reached a different sentencing result if it had been presented with evidence of [Mr.
    Smith’s] chronic use of PCP and its allegedly attendant brain damage.” 
    Id. 11 According
    to Dr. Mash, “wet” is slang for a method of PCP ingestion that
    involves “dipping cigarettes or marijuana cigarettes in liquid PCP” or a solution of
    PCP and embalming fluid.
    34
    Mr. Smith raises three challenges to the OCCA’s conclusion. First, he argues
    the OCCA unreasonably “presupposed that Mr. Smith’s organic brain damage and
    low intelligence [were] caused by long-term daily use of [PCP].” (Alterations in
    original, internal quotation marks omitted.) He contends that Dr. Saint Martin
    attributed only some of his impairments to PCP use but “made clear there is evidence
    from [Mr. Smith’s] school records and developmental history that he had significant
    intellectual impairments before he began using illicit substances.” (Internal quotation
    marks omitted.) Thus, he claims, “[a]ny statement that Mr. Smith’s intellectual
    limitations were caused exclusively by his substance abuse is objectively
    unreasonable.”
    In making this argument, Mr. Smith ignores his own briefing of the claim in
    his second Application for Post-Conviction Relief. As discussed above, Mr. Smith’s
    argument before the OCCA focused exclusively on his drug abuse as a cause of brain
    damage and low intelligence. Indeed, in presenting Dr. Saint Martin’s opinion to the
    OCCA, Mr. Smith omitted language from the quoted portions of Dr. Saint Martin’s
    report that attributed Mr. Smith’s “mental retardation” to “prenatal or idiopathic
    brain insult” and opined that his neuropsychological deficits could also be due to “the
    factors causing his idiopathic mental retardation.” The OCCA’s view of Mr. Smith’s
    theory as claiming that his alleged brain damage and low intelligence were caused by
    his history of drug abuse is not unreasonable in light of Mr. Smith’s selective
    quotation of his own experts’ opinions to present precisely that picture to the court.
    35
    Second, Mr. Smith contends the OCCA’s characterization of this evidence as
    having a “double-edged quality” is contrary to established Supreme Court precedent.
    Mr. Smith contends the Supreme Court “rejected the ‘double-edged’ characterization
    of this type of mitigating evidence” in Sears. In particular, he relies on the Court’s
    statement in Sears that “[c]ompetent counsel should have been able to turn some of
    the adverse evidence into a positive—perhaps in support of a cognitive deficiency
    mitigation 
    theory.” 561 U.S. at 951
    . Thus, Mr. Smith contends, Sears constitutes a
    clearly established rejection of the “double-edged” theory of prejudice employed by
    the OCCA.
    We cannot agree that Sears clearly prohibits courts from considering the
    “doubled-edged” nature of mental-health and substance-abuse evidence in evaluating
    prejudice resulting from its omission during the penalty phase of trial. We first note
    that Mr. Smith relies on a portion of Sears discussing the attorney-performance
    element of the petitioner’s Strickland claim, not prejudice. Thus, to the extent Sears
    can be read as establishing a general rule relating to the handling of this type of
    evidence, it establishes at best that an attorney’s failure to use evidence of
    “substantial deficits in mental cognition and reasoning” in some positive fashion may
    constitute deficient performance. But because the OCCA never reached the issue of
    deficient performance, Sears does not control our analysis here. 12
    12
    The Court in Sears did determine the state court’s analysis of prejudice was
    flawed, but it did so on a different ground. Sears v. Upton, 
    561 U.S. 945
    , 954–56
    (2010). The state trial court had failed to consider both the newly uncovered evidence
    36
    Moreover, the Supreme Court has explicitly recognized that mental-health
    evidence, including evidence of low intelligence, can have a double-edged impact on
    the jury. In Atkins v. Virginia, the court specifically noted that the intellectually
    disabled face “a special risk of wrongful execution” in part because “reliance on
    mental retardation as a mitigating factor can be a two-edged sword that may enhance
    the likelihood that the aggravating factor of future dangerousness will be found by
    the jury.” 
    536 U.S. 304
    , 321 (2002). And subsequent to Sears, in Cullen v.
    Pinholster, the Court reiterated the principle, citing Atkins for the proposition that
    “mitigating evidence can be a ‘two-edged sword’ that juries might find to show
    future dangerousness.” 
    563 U.S. 170
    , 201 (2011). Like this case, Cullen involved a
    claim of ineffective assistance for trial counsel’s failure to introduce mitigating
    evidence. There, the Court concluded that the bulk of new evidence presented by the
    petitioner in support of his state habeas petition—evidence that he suffered from
    bipolar mood disorder and that his family had a history of “serious substance abuse,
    mental illness, and criminal problems”—was of “questionable mitigating value”
    because it could have opened the door to rebuttal and may have convinced the jury
    the petitioner “was simply beyond rehabilitation.” 
    Id. Because the
    other new
    evidence presented by the petitioner was “sparse,” the Court held the state court did
    and the evidence introduced at trial in weighing the probability of a different
    sentencing result. 
    Id. at 955–56.
    Accordingly, the Supreme Court remanded for the
    state court to perform a proper prejudice analysis. 
    Id. at 956.
    37
    not unreasonably conclude that the petitioner had failed to demonstrate prejudice
    under Strickland. 
    Id. at 202.
    From these decisions, it is apparent the Supreme Court did not clearly establish
    in Sears that mental-health and substance-abuse evidence cannot be viewed as
    “double-edged” in evaluating the prejudicial effect of omitting such evidence in the
    penalty phase.13 “The absence of clearly established federal law is dispositive under
    § 2254(d)(1).” Hooks v. Workman, 
    689 F.3d 1148
    , 1163 (10th Cir. 2012) (internal
    quotation marks omitted).
    Last, Mr. Smith argues more generally that the OCCA’s prejudice
    determination was unreasonable. We interpret this challenge as a claim that the
    OCCA unreasonably applied the Strickland analysis. He contends “the OCCA’s
    reliance on the role of the continuing threat aggravating circumstance” is
    unreasonable because the jury “had already heard the State’s case in aggravation,
    including evidence of Mr. Smith’s behavior.” Although Mr. Smith does not develop
    this argument further, he presumably seeks to liken his case to those like Smith v.
    Mullin, where we have concluded that the aggravating “edge” of the evidence was
    blunted because the negative aspects of the evidence had already been placed before
    the jury. 
    379 F.3d 919
    , 943 & n.11 (10th Cir. 2004). But Mr. Smith does not explain
    how the aggravating edge of this evidence—that damage to his brain was caused or
    13
    Mr. Smith also contends our own precedents “foreclose a finding of no
    prejudice on the ‘double-edged’ characterization.” But none of the decisions Mr.
    Smith cites have addressed the dispositive question here: whether the Supreme Court
    has clearly established the rule he seeks to apply to the OCCA’s decision.
    38
    exacerbated by habitual drug use—was before the jury in such a way that it was
    unreasonable for the OCCA to conclude the evidence was likely to be as harmful to
    him as helpful. Absent such a showing, we cannot conclude the OCCA’s application
    of Strickland was unreasonable.14
    Mr. Smith has failed to demonstrate the OCCA unreasonably concluded he
    was not prejudiced by his trial counsel’s failure to present additional evidence in
    mitigation. Absent a showing of prejudice, his claims under Strickland must fail. We
    therefore affirm the district court’s denial of habeas relief on Mr. Smith’s ineffective-
    assistance claims.
    D. Cumulative Error
    As a final point, Mr. Smith contends he is entitled to relief on the basis of
    cumulative error. “A cumulative-error analysis aggregates all errors found to be
    harmless and analyzes whether their cumulative effect on the outcome of the trial is
    such that collectively they can no longer be determined to be harmless.” Cargle v.
    Mullin, 
    317 F.3d 1196
    , 1206 (10th Cir. 2003). “The cumulative-error analysis applies
    where there are two or more actual errors. It does not apply, however, to the
    cumulative effect of non-errors.” United States v. Franklin-El, 
    555 F.3d 1115
    , 1128
    (10th Cir. 2009) (internal quotation marks omitted). Respondent contends our review
    14
    Mr. Smith also contends the OCCA failed to properly conduct a totality of
    the evidence review under Strickland and “considered only Mr. Smith’s ‘chronic use
    of PCP and its allegedly attendant brain damage,’” rather than all of the evidence
    offered in mitigation, to evaluate prejudice. Mr. Smith has identified nothing in the
    OCCA’s decision to suggest its analysis was so limited, and we can identify nothing
    that lends merit to Mr. Smith’s claim.
    39
    of this claim is constrained by AEDPA and that no clearly established federal law
    recognizes cumulative error as a ground for habeas relief. However, because we can
    easily resolve these claims on the merits, it is not necessary for us to evaluate what
    deference may be owed to the OCCA under the circumstances.
    Mr. Smith identifies what he terms two “clusters” of error that he contends
    cumulatively deprived him of a fair trial. With respect to the first cluster, Mr. Smith
    argues his trial counsel’s ineffectiveness, his claimed intellectual disability, and the
    admission of his confession “individually and in combination resulted in an
    unreliable sentence of death.” Because we have concluded that the OCCA did not
    unreasonably reject Mr. Smith’s Atkins claim or his challenge to the admission of his
    confession, there are not “two or more actual errors” to cumulate with respect to this
    claim. 
    Id. (internal quotation
    marks omitted).
    The second cluster of errors Mr. Smith identifies involves the admission of his
    confession compounded with the trial court’s error in responding to a jury question
    outside the presence of Mr. Smith’s counsel, an error the OCCA recognized on direct
    appeal. Because we have concluded the OCCA did not unreasonably reject Mr.
    Smith’s challenge to the admission of his confession, there is only one error—the
    trial court’s response to the jury’s question—and, therefore, nothing for us to
    cumulate.
    Thus, Mr. Smith has failed to demonstrate that the cumulative effect of two or
    more errors had a prejudicial effect on the outcome of his trial, and he is not entitled
    to habeas relief on this claim.
    40
    IV. CONCLUSION
    Mr. Smith has failed to demonstrate that the OCCA’s decisions on his
    intellectual disability, Miranda waiver, or ineffective-assistance claims were
    unreasonable. The district court properly denied habeas relief on each of Mr. Smith’s
    claims. We therefore AFFIRM the judgment of the district court.
    41