Robert Ybarra, Jr. v. William Gittere ( 2023 )


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  •                 FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    ROBERT YBARRA, Jr.,                      No. 20-99012
    Petitioner-Appellant,         D.C. No.
    3:00-cv-00233-
    v.                                       GMN-VPC
    WILLIAM GITTERE, Warden,
    OPINION
    Respondent-Appellee.
    Appeal from the United States District Court
    for the District of Nevada
    Gloria M. Navarro, District Judge, Presiding
    Argued and Submitted March 22, 2023
    Pasadena, California
    Filed June 9, 2023
    Before: Richard C. Tallman, Richard R. Clifton, and
    Danielle J. Forrest, Circuit Judges.
    Opinion by Judge Tallman
    2                       YBARRA V. GITTERE
    SUMMARY*
    Habeas Corpus / Death Penalty
    The panel affirmed the district court’s denial of Robert
    Ybarra Jr.’s federal petition for a writ of habeas corpus in a
    case in which Ybarra, who was sentenced to death for a 1979
    murder, argued that he is intellectually disabled and
    therefore cannot constitutionally be executed under Atkins v.
    Virginia, 
    536 U.S. 304
     (2002).
    This court previously identified several errors in the
    Nevada Supreme Court’s reasoning but remanded for the
    federal district court to determine whether the Nevada
    Supreme Court’s overall intellectual disability determination
    was unreasonable.
    On remand, the district court concluded that it was not
    and thus denied Ybarra’s petition for relief.
    In this appeal, the panel held that Ybarra’s claim fails on
    the first prong (“Prong 1”) of the three prongs required for
    relief on an Atkins claim—he failed to establish that he
    suffered from significantly subaverage intellectual
    functioning.
    Ybarra argued that the Nevada Supreme Court
    unreasonably found that a 1981 IQ test was of “little value”
    because it was conducted well after Ybarra turned 18 and
    refused to consider any evidence outside the developmental
    period. The panel wrote that this argument is belied by a fair
    *
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    YBARRA V. GITTERE                      3
    reading of the Nevada Supreme Court’s opinion, which gave
    three reasons for rejecting Ybarra’s arguments. First, the
    Nevada Supreme Court explicitly rejected Ybarra’s
    argument that the trial court had erred in crediting the 1981
    IQ test over another expert’s testing. The second reason was
    that, based on “Ybarra’s school and other records, his
    writings, and evidence that he was malingering,” the record
    as a whole (irrespective of the various IQ test scores)
    portrays Robert Ybarra as a person who does not have
    significant subaverage intellectual functioning.” Finally, the
    Nevada Supreme Court said that it “need not decide the
    relevance, if any, of” the Flynn Effect, which causes average
    IQ test scores to inflate over time, “and the necessity of
    adjusting the 1981 IQ score” because that test occurred well
    after Ybarra turned 18. The panel wrote that even if the final
    reason was an unreasonable deviation from the clinical
    guidelines, the first reason was not. The panel wrote that the
    Nevada Supreme Court’s second reason for rejecting
    Ybarra’s criticism of the 1981 IQ test was also
    reasonable. The panel wrote that, taken in context, it is clear
    the Nevada courts did not base their Prong 1 determination
    on a “lay perception that Ybarra did not ‘look like’ a disabled
    person.”
    Ybarra’s second argument was that reliance on anything
    other than expert testimony amounts to a reliance on
    “stereotypes” about intellectual disability. The panel wrote
    that this is incorrect: every expert, including Ybarra’s
    experts, testified that, in forming their conclusions, they had
    interviewed Ybarra, reviewed records about Ybarra, or
    both. To the extent Ybarra’s experts relied on faulty
    evidence (i.e., false statements by Ybarra during testing) or
    failed to consider evidence (i.e., records suggesting Ybarra
    was not intellectually disabled) it was not unreasonable to
    4                     YBARRA V. GITTERE
    find that their conclusions were invalid—especially since the
    trial court also considered Test of Memory Malingering
    (“TOMM”) results. The panel wrote that even if the Nevada
    Supreme Court gave little weight to both the 1981 IQ test
    and the TOMM test, the Prong 1 finding is still not
    unreasonable.
    Because the panel found that the Nevada Supreme
    Court’s Prong 1 determination was reasonable, the panel did
    not consider the second and third Atkins prongs or the related
    procedural history.
    COUNSEL
    Randolph Fiedler (argued), Hannah D. Nelson, and Joanne
    L. Diamond, Assistant Federal Public Defenders; Rene L.
    Valladares, Federal Public Defender of the District of
    Nevada; Federal Public Defenders’ Office; Las Vegas,
    Nevada; for Petitioner-Appellant.
    Jeffrey M. Conner (argued), Deputy Solicitor General;
    Heather D. Procter, Deputy Attorney General; Aaron D.
    Ford, Attorney General of Nevada; Office of the Nevada
    Attorney General; Carson City, Nevada; for Respondent-
    Appellee.
    YBARRA V. GITTERE                      5
    OPINION
    TALLMAN, Circuit Judge:
    The State of Nevada sentenced Robert Ybarra to die for
    brutally raping and murdering 16-year-old Nancy Griffith in
    1979. Ybarra pled not guilty by reason of insanity but was
    convicted by the jury after a trial in the District Court for
    White Pine County in Ely, Nevada. Ybarra argues that he is
    intellectually disabled and therefore cannot constitutionally
    be executed under Atkins v. Virginia, 
    536 U.S. 304
     (2002).
    The Nevada trial court held a hearing on Ybarra’s Atkins
    claim and found he was not intellectually disabled, and the
    Nevada Supreme Court affirmed. Ybarra filed a petition for
    a writ of habeas corpus in federal district court which is
    subject to the restrictions of the Antiterrorism and Effective
    Death Penalty Act of 1996 (AEDPA), 
    28 U.S.C. § 2254
    .
    Ybarra argues that the Nevada Supreme Court’s
    determination that he is not intellectually disabled is
    unreasonable under § 2254(d)(2).
    We previously identified several errors in the Nevada
    Supreme Court’s reasoning but remanded for the federal
    district court to determine whether the overall intellectual
    disability determination was unreasonable. See Ybarra v.
    Filson (Ybarra IV), 
    869 F.3d 1016
    , 1026 (9th Cir. 2017). On
    remand, the federal district court concluded that it was not
    and thus denied Ybarra’s petition for relief. We agree and
    affirm. Because we ultimately conclude that Ybarra’s Atkins
    claim fails on the first prong—that he failed to establish that
    he suffered from significantly subaverage intellectual
    functioning—we do not consider the second and third Atkins
    prongs or the related procedural history. See Apelt v. Ryan,
    6                        YBARRA V. GITTERE
    
    878 F.3d 800
    , 837 (9th Cir. 2017) (stating that a petitioner
    must meet all three Atkins prongs to prevail on his claim).
    Pursuant to § 2253(c), the district court granted a
    certificate of appealability on the following issue: “Whether
    [the district] court erred in deferring, under 
    28 U.S.C. § 2254
    (d), to the state court’s finding that petitioner is not
    intellectually disabled as contemplated by Atkins v. Virginia,
    
    536 U.S. 304
     (2002), and its progeny?”
    BACKGROUND
    As recounted in prior opinions, this case has a complex
    and protracted history spanning 42 years. There have been
    several rounds of review in both state and federal courts.1
    While we have attempted to limit our discussion to factual
    and procedural matters relevant to Ybarra’s Atkins claim, our
    summary remains lengthy.
    A
    1
    On September 29, 1979, two fishermen from Ely,
    Nevada, found sixteen-year-old Nancy Griffith lying on an
    unpaved road near that town. Ybarra v. State (Ybarra I), 
    679 P.2d 797
    , 798 (Nev. 1984). Nancy’s body was badly burned,
    but she was still alive. 
    Id. at 798-99
    . Nancy told a sheriff’s
    deputy that she had been raped by a man in a red truck who
    worked north of where she was found. 
    Id.
     She died the next
    day. 
    Id.
    1
    See generally Ybarra v. State, 
    679 P.2d 797
    , 798 (Nev. 1984); Ybarra
    v. McDaniel, 
    656 F.3d 984
     (9th Cir. 2011); Ybarra v. Baker, No. 3:00-
    cv-0233, 
    2013 WL 5567586
     (D. Nev. Oct. 8, 2013); Ybarra v. Filson,
    
    869 F.3d 1016
     (9th Cir. 2017).
    YBARRA V. GITTERE                     7
    The investigation into Nancy’s murder revealed that on
    the evening of September 28, Nancy had met Robert Ybarra
    in Ely. 
    Id.
     Ybarra worked on an oil rig near town and had
    driven Nancy and her friend around in his truck. 
    Id.
     After
    her friend had left, Ybarra drove Nancy outside Ely where
    he raped and attempted to murder her. See 
    id.
     Ybarra was
    arrested and charged with first degree murder, first degree
    kidnapping, battery with intent to commit sexual assault, and
    sexual assault. Id. at 798. At his state court trial, Ybarra’s
    only defense was insanity. Id. at 799. It failed. Ybarra was
    convicted by a jury and sentenced to three consecutive life
    sentences and death. Id. at 799-800.
    2
    Ybarra was born in Sacramento, California, on July 20,
    1953. His mother was either 15 or 16 when he was born, and
    he had three younger brothers and one younger sister.
    Ybarra’s development was apparently fairly normal until age
    9, when he was struck in the forehead by a railroad tie being
    used as a swing. After the head injury, Ybarra suffered
    migraines, and was prescribed various medications
    including Mebaral, a barbiturate which has sedative and anti-
    convulsant effects. Ybarra also suffered from auditory
    hallucinations and depression and started using drugs and
    alcohol.
    By age 14, Ybarra was falling behind in school. Other
    students bullied him, including by calling him a “retard” on
    a daily basis. His doctor prescribed an amphetamine.
    Ybarra eventually transferred schools due to “peer problems
    and academic failure” before ultimately dropping out of high
    school entirely in 1969 at age 15. Ybarra instead attended
    night school, worked during the day, and received an adult
    education diploma just prior to age 19. Ybarra also enlisted
    8                        YBARRA V. GITTERE
    in the U.S. Marine Corps. Mental testing conducted by the
    military showed that Ybarra’s intelligence was “dull
    normal” or “borderline,” but he was found fit for duty. He
    was later discharged for homosexual conduct. Ybarra
    attempted to re-enlist in the Marine Corps but was
    recognized and kicked out. He also enlisted in the National
    Guard but was discharged again due to asthma.
    Around 1974, Ybarra moved to Oregon where he met a
    woman who would later become his wife. They moved back
    to Sacramento where Ybarra’s wife became pregnant;
    however, in 1979 she left him and returned to Oregon.
    Ybarra then worked in Montana before later moving to Ely
    in September of 1979. Ybarra worked throughout this period
    and was employed at the time of Nancy’s murder. He was
    then 26 years old.
    B
    On June 20, 2002, the United States Supreme Court
    decided Atkins v. Virginia, holding that the execution of
    intellectually disabled individuals violates the Eighth
    Amendment’s prohibition on cruel and unusual
    punishment.2 
    536 U.S. at 321
    . However, Atkins recognized
    that there was still “serious disagreement” about who
    qualifies as intellectually disabled and “le[ft] to the State[s]
    the task of developing appropriate ways to enforce the
    constitutional restriction.” 
    Id. at 317
     (second alteration in
    original) (quoting Ford v. Wainwright, 
    477 U.S. 399
    , 416-
    17 (1986)).
    2
    When Atkins was decided, courts and medical groups used the term
    “mental retardation.” Medical authorities have subsequently adopted the
    term “intellectually disabled.” We adopt the modern terminology,
    except when directly quoting from older documents.
    YBARRA V. GITTERE                            9
    To comply with Atkins, the Nevada Legislature in 2003
    adopted Nevada Revised Statute section 174.098.3 See
    Ybarra v. State (Ybarra II), 
    247 P.3d 269
    , 273 (Nev. 2011).
    That statute provides that a defendant who is intellectually
    disabled may file a motion to strike the death penalty. 
    Nev. Rev. Stat. § 174.098
    (1), (6). “The defendant has the burden
    of proving by a preponderance of the evidence that the
    defendant is intellectually disabled.” § 174.098(5)(b). The
    statute establishes a three-pronged test for intellectual
    disability:
    (1) “significant         subaverage       general     intellectual
    functioning[;]”
    (2) “which exists concurrently with deficits in adaptive
    behavior[;]” and
    (3) which “manifested during the developmental
    period.”
    § 174.098(7). This definition is similar to the clinical
    definition used by the American Association on Intellectual
    and Developmental Disabilities (AAIDD)4 and the
    American Psychiatric Association (APA). Ybarra II, 
    247 P.3d at 274
    .
    We first discuss the evidence presented at Ybarra’s
    Atkins hearing, the state trial court’s ruling, and the Nevada
    3
    The Nevada legislature updated this statute in 2013 and in 2015 simply
    to remove the outdated language “mentally retarded” and replace it with
    “intellectually disabled.” The statute remains identical in all other
    respects. Compare 
    Nev. Rev. Stat. Ann. § 174.098
     (2013), (2015) with
    
    Nev. Rev. Stat. Ann. § 174.098
     (2003).
    4
    Previously called the American Association on Mental Retardation
    (AAMR).
    10                   YBARRA V. GITTERE
    Supreme Court’s opinion affirming that ruling. We then turn
    to our previous opinion, Ybarra v. Filson (Ybarra IV), 
    869 F.3d 1016
     (9th Cir. 2017), and the federal district court’s
    ruling on remand.
    1
    After the adoption of section 174.098, Ybarra filed a
    motion to strike the death penalty. In April 2008, the Nevada
    state trial court held a two-day evidentiary hearing on
    Ybarra’s motion. The trial court (Hon. Steve L. Dobrescu)
    considered new evidence from two experts who testified on
    behalf of Ybarra (Drs. David Schmidt and Mitchell Young)
    and one who testified on behalf of the state (Dr. Ted Young).
    The trial court also considered roughly 3,000 pages of
    written exhibits.
    A
    Dr. David Schmidt, a licensed clinical psychologist, was
    initially retained by Ybarra’s counsel in 2000 to help
    develop mitigation evidence but, after Atkins was decided,
    he was asked to testify about whether Ybarra was
    intellectually disabled. Dr. Schmidt administered the
    Wechsler Adult Intelligence Scale III (WAIS III) test and
    other intelligence tests but conceded his testing was
    “problematic . . . at best” because of Ybarra’s “problems
    with anxiety and . . . hallucinations and various things that
    were going on during the time of the testing.” The WAIS III
    administered by Dr. Schmidt revealed Ybarra’s IQ was 60.
    According to Dr. Schmidt, after accounting for measurement
    error in IQ scores, a score of 75 or below indicates the
    reduced level of intellectual functioning associated with
    intellectual disability. Dr. Schmidt opined that it would be
    difficult but not impossible for an individual to fake
    intellectual disability on an IQ test.
    YBARRA V. GITTERE                     11
    Dr. Schmidt also concluded that Ybarra suffered from
    deficits in adaptive behaviors because he had difficulty in
    school, had been bullied by classmates, lacked social skills,
    could not hold a job, had never had a job with more than
    minimum wage pay, was unable to remain in the military,
    and was not able to live on his own. For example, Dr.
    Schmidt cited a 1969 letter from a doctor who opined that,
    at age 16, Ybarra should have received a medical exclusion
    from school because he had “gone about as far as he can go
    within [the] limits of his intellectual and emotional
    capabilities.” Dr. Schmidt concluded that Ybarra’s adaptive
    deficits and significantly subaverage intellectual functioning
    had manifested in his “developmental years” and offered his
    professional opinion that Ybarra was “mentally retarded.”
    Dr. Schmidt also testified about an IQ test that Ybarra
    had been given in 1981 by Dr. Martin Gutride while
    Ybarra’s competency was being evaluated prior to his trial.
    This test showed Ybarra’s IQ was 86. Dr. Schmidt testified
    that unlike the newer WAIS III test he administered to
    Ybarra, the WAIS test administered in 1981 was 26 years
    old at the time it was administered, and therefore had been
    affected by the “Flynn Effect.” Because IQ is a measure of
    relative rather than absolute intelligence, the Flynn Effect
    causes average IQ test scores to “inflate” over time, meaning
    that IQ tests must be periodically “re-normed” to ensure they
    are accurate. Dr. Schmidt suggested that the failure to re-
    norm the test meant Ybarra’s 1981 score could have been
    artificially inflated by as much as 15 points. Dr. Schmidt
    also criticized the 1981 test because Dr. Gutride’s intern had
    assisted with the testing.
    In response to objections and cross-examination from the
    state, Dr. Schmidt agreed that an earlier version of his expert
    report included a “bold print” disclaimer stating that the
    12                    YBARRA V. GITTERE
    WAIS III test he had administered “may underestimate
    [Ybarra’s] actual intellectual functioning” because of “the
    severe distress” testing caused Ybarra. This disclaimer was
    apparently removed from the final report. Later, Dr.
    Schmidt testified that he had “good confidence” in his
    testing but also seemed to equivocate: “[A]s I went back and
    reviewed post-Adkins [sic], this was a case to me that may or
    may not fit the standard, but certainly bears looking at
    further.” Dr. Schmidt also admitted that if someone has
    taken multiple IQ tests, the higher score generally controls
    because it is not possible to fake a higher score. With respect
    to the 1981 IQ test, administered by Dr. Gutride, Dr. Schmidt
    conceded he could not “express an opinion about the validity
    of that test” with professional certainty.
    The state further cross-examined Dr. Schmidt about the
    evidence he reviewed to reach his conclusions, including the
    military test, which showed Ybarra’s intelligence was “dull
    normal”; Ybarra’s marriage and the household he formed
    with his wife; and Dr. Schmidt’s failure to interview
    Ybarra’s prison guards or review prison records. The state
    also cross-examined Dr. Schmidt about Ybarra’s school
    records, including a letter from Ybarra’s seventh-grade
    teacher, which stated that he did not recall Ybarra “having
    any learning problems.” Dr. Schmidt was generally
    unwilling to give any ground on cross-examination. For
    example, when asked about the teacher’s letter, Dr. Schmidt
    suggested it was of little value because it was based on a 35-
    year-old recollection. When the state pointed out that Dr.
    Schmidt had relied on the 35-year-old recollections of
    Ybarra’s family members, Dr. Schmidt responded that the
    teacher only saw Ybarra “for 50 minutes at a time in a class
    of 35 students.”
    YBARRA V. GITTERE                     13
    B
    Ybarra’s second expert witness was Dr. Mitchell Young,
    a psychiatrist. As Dr. M. Young started to testify, the state
    asked “what is that note pad that you’re reading from?” Dr.
    M. Young explained that he had not seen “the applicable
    legal standard relevant to matters before the court until
    yesterday morning” and “was not familiar” with the
    language of Atkins. Ybarra’s counsel explained that Dr. M.
    Young was asked to “think in terms of what the Supreme
    Court noticed or held why those with mental retardation are
    barred from execution” and “address the concept of adaptive
    deficits in that context.” Dr. M. Young then clarified that he
    was not intending to be a “substitute decision maker” for the
    court because “legal matters and diagnostic matters don’t
    have . . . a one-to-one correspondence.”
    Dr. M. Young’s report indicates that he administered a
    Survival Skills Quotient (SSQ) test to Ybarra and obtained a
    score of 79. The SSQ is a “test of adaptive behavior,” and
    the raw score is “comparable to IQ.” Ybarra’s score was “in
    the borderline range of [intellectual disability].” Dr. M.
    Young also administered a test called the Rare Symptoms
    Scale, which is designed to detect malingering. Ybarra had
    a “markedly elevated” score on this test, and “tended to
    endorse items that untrained individuals are likely to identify
    as obvious signs of a major mental illness.” The report
    nonetheless concludes that Ybarra “suffered and continues
    to suffer deficits in adaptive functioning” prior to age 18. At
    the hearing, Dr. M. Young testified that, to prepare his
    report, he had interviewed Ybarra and reviewed documents,
    including Dr. Schmidt’s report, but that he could not reach a
    conclusion about whether Ybarra was intellectually disabled
    based solely on this evidence.
    14                    YBARRA V. GITTERE
    However, Dr. M. Young then said that he wanted to
    change his conclusion from that offered in his written expert
    report. Dr. M. Young had originally concluded that Ybarra
    was in the “mild to borderline mentally retarded range”
    based in part on the 1981 IQ score and Ybarra’s adaptive
    deficits. However, based on what he had just learned from
    listening to Dr. Schmidt’s testimony about the impact of the
    Flynn Effect and other issues with the 1981 test, he now
    believed that Ybarra qualified as intellectually disabled
    under the AAMR and APA standards. Dr. M. Young then
    opined that Ybarra suffered from adaptive behavioral
    deficits prior to age 18. Finally, Dr. M. Young testified that
    a 1991 medical report and Dr. Schmidt’s testing indicated
    Ybarra had suffered from a brain injury during the
    developmental period.
    On cross-examination, the state attacked the data on
    which Dr. M. Young had relied to form his conclusions. For
    example, Dr. M. Young agreed that his opinion would
    change again if Dr. Schmidt’s test scores were erroneous.
    Dr. M. Young also testified about Ybarra’s past statements
    which indicated that he was malingering, such as a statement
    Ybarra made in 1991 about how he never thought he would
    end up “having to act crazy” and a statement Ybarra made in
    1981 about how he did not want to die by execution and
    would fight to stay alive. Dr. M. Young conceded that he
    had considered the possibility that Ybarra was faking his
    symptoms but insisted that malingering and intellectual
    disability “can co-exist and frequently do.”
    C
    The state called Dr. Theodore Young, a licensed
    psychologist, to testify about his objective testing of
    Ybarra’s cognitive ability. Dr. T. Young interviewed Ybarra
    YBARRA V. GITTERE                            15
    and then administered objective tests of Ybarra’s cognitive
    ability, including an abbreviated WAIS III test. The initial
    results of the objective testing were “bizarre” and not “in any
    way typical of patients” that Dr. T. Young sees. This caused
    Dr. T. Young to suspect Ybarra was malingering. For
    example, Dr. T. Young administered the “Rey Complex
    Figure” test, which involves copying lines from a picture.
    Ybarra’s performance on this test was so poor that it was
    impossible to score. Dr. T. Young noted that he had
    administered this test over 10,000 times, and that Ybarra’s
    results were worse than those seen in Alzheimer’s patients
    or among those with similarly debilitating diseases. Dr. T.
    Young also observed that Ybarra was apparently unable to
    spell two-, three-, and four-letter words, which was
    inconsistent with past samples of Ybarra’s writing.5
    Dr. T. Young went on to test Ybarra’s intelligence using
    the abbreviated WAIS III. He found Ybarra’s IQ was 66,
    which suggested “mild mental retardation.” However, Dr.
    T. Young testified that the result was “not even close to
    being valid” because of Ybarra’s malingering. Dr. T. Young
    testified that he also administered the “Test of Memory
    Malingering” (TOMM). The TOMM results suggested that
    Ybarra was malingering. Dr. T. Young testified that while
    some literature urges that a lower cut-off score should apply
    when the TOMM is used to test for malingering among a
    person who may be intellectually disabled, Ybarra’s score
    was well below even the lower threshold advocated by some
    5
    Ybarra argues the trial court’s order misquotes Dr. T. Young’s
    testimony about the results of the spelling test. However, the trial court
    noted that the official transcripts of the proceedings have significant
    errors and relied at least in part on the videotaped transcript of
    proceedings.
    16                   YBARRA V. GITTERE
    studies. Dr. T. Young was also asked about Dr. M. Young’s
    report that Ybarra had “a markedly elevated score” on a test
    of rare psychiatric symptoms and agreed that this unusual
    result was similar to his own experience testing Ybarra.
    Dr. T. Young strongly criticized Dr. Schmidt’s testing of
    Ybarra, which he said did not meet APA standards because
    Dr. Schmidt failed to test for malingering. Dr T. Young
    specifically concluded that Dr. Schmidt’s test was “invalid”
    because it was “absolutely clear . . . that the question of
    [Ybarra’s] effort was not adequately addressed.” Dr. T.
    Young also testified about the 1981 IQ test score of 86
    obtained by Dr. Gutride and stated that this score put Ybarra
    “well above” the range for intellectual disability, which was
    “as high as 75.” Dr. T. Young testified that while he had
    heard Dr. Schmidt’s testimony that the 1981 test
    administered to Ybarra was obsolete, in fact the revised
    WAIS had not been released until after Ybarra’s 1981 test,
    meaning Ybarra received the most current test then
    available. Finally, Dr. T. Young testified that Dr. Gutride’s
    use of an intern to conduct the 1981 testing was not
    problematic because Dr. Gutride co-signed the report and
    remained fully professionally responsible for the finding.
    On cross-examination, Dr. T. Young conceded that he
    had not evaluated the other two prongs required to establish
    intellectual disability—adaptive deficits and onset during
    the developmental period—because without a valid IQ test
    within the necessary range, “these other prongs don’t
    matter.” However, Dr. T. Young noted he had reviewed the
    same documentation about Ybarra that was available to Dr.
    M. Young and Dr. Schmidt and criticized their failure to
    objectively test Ybarra’s adaptive functioning. Dr. T. Young
    also admitted that he had initially produced his report as an
    “interim” report, which addresses only his objective testing
    YBARRA V. GITTERE                    17
    of Ybarra’s intellectual functioning because the background
    information about Ybarra had not yet been made available to
    him.
    Dr. T. Young further agreed that he had not read the most
    current AAMR manual and had last reviewed the 1992
    edition. He testified that he had read the portions of the
    current manual that were “reprinted in the Atkins decision”
    because he had reviewed that decision while preparing for
    his testimony. Ybarra’s attorney also cross-examined Dr. T.
    Young about the studies supporting the use of the TOMM
    test to identify feigned intellectual disability. Ybarra’s
    counsel and Dr. T. Young disagreed about the meaning of
    the treatise on which Dr. T. Young relied; the attorney
    pointed out that the treatise did not recommend use of the
    TOMM to identify feigned intellectual disability; Dr. T.
    Young contended that the treatise supported his conclusion
    that Ybarra’s low score on the TOMM indicated
    malingering.
    2
    The Nevada district judge concluded that Ybarra failed
    to demonstrate by a preponderance of the evidence that he
    was intellectually disabled. The state court started by
    defining the relevant developmental period for the purposes
    of section 174.098. Based on his review of other states’
    laws, expert testimony, and the AAMR standards, Judge
    Dobrescu determined that the relevant developmental period
    was up to age 18.. However, Judge Dobrescu went on to
    consider evidence about Ybarra’s intellectual functioning
    and adaptive behavioral deficits from outside that period
    because all the aforementioned testing occurred while
    Ybarra was in his mid-twenties or older.
    18                   YBARRA V. GITTERE
    With respect to Prong 1, Ybarra’s intellectual
    functioning, Judge Dobrescu determined that Ybarra failed
    to show the onset of significant subaverage intellectual
    functioning during the developmental period.          Judge
    Dobrescu noted that when Ybarra was tested by the Marine
    Corps, intelligence testing showed he was “dull normal” or
    “borderline,” which is not intellectually disabled. The trial
    court credited the 1981 IQ test administered by Dr. Gutride,
    which had showed Ybarra’s IQ was 86. The court also
    considered other medical records, interviews, and testing
    conducted by psychiatrists and psychologists after Ybarra’s
    arrest, which suggested that his intelligence was below
    average but not intellectually disabled.
    Judge Dobrescu rejected Dr. Schmidt’s testimony about
    the impact of the Flynn Effect on the 1981 IQ test, finding
    that “numerous courts have rejected the notion of adjusting
    IQ scores to accommodate the Flynn Effect.” However, the
    court noted that even after adjusting for the Flynn Effect,
    Ybarra’s IQ would be 78—i.e., not intellectually disabled.
    Judge Dobrescu also rejected Dr. Schmidt’s 2002 IQ test
    showing Ybarra’s IQ was 60, noting the original “bold-faced
    disclaimer” in Dr. Schmidt’s report which suggested
    Ybarra’s IQ could have been underestimated and Dr.
    Schmidt’s failure to employ any kind of test for malingering.
    The court noted that Dr. T. Young had specifically criticized
    Dr. Schmidt’s failure to test for malingering and that Dr.
    Schmidt had been recalled to the stand but failed to respond
    to that criticism. Finally, the court rejected Dr. Schmidt’s
    criticism of the 1981 IQ test as “pure speculation” and
    concluded that the 1981 score was supported by
    contemporaneous records from other evaluators who
    believed Ybarra was “dull normal or borderline” but not
    “mentally retarded.”
    YBARRA V. GITTERE                    19
    Judge Dobrescu then concluded that Ybarra was likely
    malingering. While recognizing that malingering does not
    exclude the possibility that Ybarra had an intellectual
    disability, the court concluded that it must be considered in
    evaluating intellectual functioning. The court cited various
    medical records and opinions which supported Ybarra’s
    history of malingering, including:
    •   A 1979 examination from a Doctor Lynn Gerow,
    who administered the Minnesota Multiphasic
    Personal Inventory (MMPI), and concluded Ybarra
    had “made an attempt to answer each question in a
    positive manner to indicate psychopathology.”
    •   A 1981 letter from Doctor Donald Molde, who
    concluded that Ybarra’s claims to suffer from
    hallucinations were “due to extra medical
    considerations” rather than mental illness.
    •   A 1981 letter from Doctor Richard Lewis, who, after
    reviewing three MMPI profiles administered to
    Ybarra, concluded that “the probability is very high”
    that Ybarra had “deliberately faked the tests in a
    pathological direction.”
    •   Ybarra’s 1981 statement to Doctor Gutride, while
    being evaluated for competency to stand trial, that he
    had “decided the best thing he could do was to pass
    the Sanity Commission so he could get on with his
    legal problems.”      Ybarra then passed three
    psychiatric examinations.
    •   A March 1981 letter from Ybarra, in which he
    indicated that he would be “nuts soon from not taking
    my meds,” and asked the recipient to “pray for me to
    get a [not guilty by reason of insanity]” so that he
    20                    YBARRA V. GITTERE
    could return to a mental health facility rather than
    remain in jail. Judge Dobrescu observed that up to
    that point, Ybarra had generally maintained he was
    actually innocent of the murder.
    •   A 1985 progress note signed by a “Dr. Knapp,”
    which indicated that Ybarra was “mentally ill” but
    “tries to fake psychosis.”
    •   A 1991 progress note recording Ybarra’s statement,
    made while in the prison mental health unit, that he
    never thought he would end up in here “having to act
    crazy.”
    Judge Dobrescu also observed that Ybarra had requested
    copies of his own medical records on several occasions,
    repeatedly refused medication, and had written hundreds of
    prison “kites” (which are “form[s] used by prison inmates to
    communicate with staff . . . .”) and other correspondence
    which showed a level of intelligence inconsistent with
    intellectual disability. Richey v. Dahne, 
    807 F.3d 1202
    , 1205
    n.3 (9th Cir. 2015). Some of Ybarra’s statements indicated
    a level of sophistication about legal defenses. For example,
    Ybarra questioned a doctor about multiple personality
    disorder and mentioned that that he knew of a person who
    had his case dismissed because he had that disorder. Judge
    Dobrescu concluded that Dr. Gutride’s 1981 IQ test was
    most likely to be valid because Ybarra had, at that point,
    decided to put forward his best effort on the test so he could
    move on with his case.
    Finally, in discussing the expert testimony, the court
    observed that Dr. Schmidt had testified that a person cannot
    fake being smarter than they actually are on an IQ test. The
    court also noted the results of Dr. T. Young’s spelling test
    and concluded that Ybarra’s apparent inability to spell
    YBARRA V. GITTERE                     21
    simple words was not consistent with letters and kites he had
    written. Finally, the court discussed Dr. T. Young’s TOMM
    test and his conclusion that there was “no valid IQ test result
    . . . below 70 in the record.” Judge Dobrescu concluded that
    the preponderance of evidence showed Ybarra “is not
    significant [sic] subaverage intellectual functioning.”
    3
    Ybarra appealed to the Nevada Supreme Court, arguing
    the trial court erred by holding that he had failed to show he
    was intellectually disabled under section 174.098(7).
    Ybarra II, 
    247 P.3d at 270
    . The Nevada Supreme Court first
    construed the definition of “mentally retarded” in the statute.
    
    Id. at 273-74
    . After examining the history of the statute, the
    appellate court concluded that “[g]iven the similarities
    between the statutory definition and the clinical definitions
    of mental retardation, the AAMR and APA provide useful
    guidance in applying the definition.” 
    Id. at 274
    . Looking to
    Prong 1—intellectual functioning—the state supreme court
    concluded that “the clinical definitions indicate that
    ‘individuals with IQs between 70 and 75’ fall into the
    category of subaverage intellectual functioning.” 
    Id.
    (quoting Am. Psychiatric Ass’n, Diagnostic and Statistical
    Manual of Mental Disorders 41 (4th ed. 2000)).
    The appellate court then considered Ybarra’s challenges
    to Judge Dobrescu’s decision, concluding it would “defer[]
    to the court’s factual findings so long as those findings are
    supported by substantial evidence and are not clearly
    erroneous, but . . . review the legal consequences of those
    factual findings de novo.” 
    Id. at 276
    . The appellate court
    described the record evidence, hearing testimony, and the
    trial court’s decision at some length. 
    Id. at 277-81
    . The
    court then turned to Ybarra’s two main arguments. Ybarra
    22                    YBARRA V. GITTERE
    argued that the trial court wrongly determined that he did not
    have subaverage intellectual functioning under Prong 1
    because it (1) “erroneously focused on the 1981 IQ test to
    the exclusion of the IQ results Dr. Schmidt obtained” and (2)
    “erroneously relied on the tests administered by the State’s
    expert because he used improper testing instruments,
    scoring, and administration techniques.” 
    Id. at 281
    .
    First, the Nevada Supreme Court found that the trial
    court had not improperly focused on the 1981 IQ test. 
    Id. at 281-83
    . Ybarra argued the trial court should not have relied
    on the 1981 IQ score because, if it had been adjusted to
    account for the Flynn Effect as suggested by Dr. Schmidt,
    the adjusted score would suggest Ybarra was mildly
    intellectually disabled. 
    Id. at 281
    . The state high court held
    that this argument failed for three separate reasons: First,
    Judge Dobrescu had found Dr. Schmidt’s testimony about
    the Flynn Effect “incredible” in light of sources that rejected
    its application and other record evidence which supported
    the “validity” of the 1981 IQ score. 
    Id. at 282
    . Nevertheless,
    the trial court had accounted for the Flynn Effect and, after
    applying an adjustment, concluded Ybarra’s IQ was 78—
    outside the range required for intellectual disability. 
    Id.
     The
    supreme court held this adjustment was “not without
    foundation.” 
    Id.
    The state high court gave two other reasons for rejecting
    Ybarra’s argument. It noted that the trial court had also
    considered other evidence in the record, such as Ybarra’s
    “school and other records, his writings, and evidence that he
    was malingering” and therefore “did not rely solely on the
    1981 IQ test.” 
    Id.
     Finally, the court observed that it did not
    need to decide the relevance of the Flynn Effect “because the
    1981 IQ test, as with all of Ybarra’s IQ tests, was
    administered well after he turned 18 years of age. Therefore,
    YBARRA V. GITTERE                    23
    this issue has little value in evaluating whether Ybarra
    presented sufficient evidence to establish mental
    retardation.” 
    Id. at 282-83
    .
    The Nevada Supreme Court then turned to Ybarra’s
    argument that the trial court had improperly relied on the IQ
    test and TOMM test administered by Dr. T. Young. 
    Id. at 283
    . The court held that the trial court’s consideration of
    Ybarra’s TOMM score did not require reversal. 
    Id.
     The
    Nevada Supreme Court reasoned that while the trial court
    “clearly” considered the TOMM results, it also considered a
    “wealth of other evidence in determining that Ybarra was
    malingering,” such as his prison kites, medical progress
    notes, and emphasized that “comments by mental health
    professionals who evaluated Ybarra during his incarceration
    indicated that their testing of Ybarra revealed malingering.”
    
    Id.
     The state supreme court then added that “as with the
    1981 IQ score, the TOMM score is of little value in
    determining whether Ybarra met his burden of proving
    significant subaverage intellectual functioning, as the
    TOMM was administered well after Ybarra reached 18 years
    of age.” 
    Id. at 283
    . The Nevada Supreme Court found that
    Ybarra had failed to show subaverage intellectual
    functioning which manifested during the developmental
    period. 
    Id. at 283-84
    .
    4
    After the Nevada Supreme Court issued its decision,
    Ybarra filed a motion to reconsider. This motion included
    as a newly offered exhibit a report dated March 28, 2012, by
    Dr. Stephen Greenspan, a psychologist and expert on
    intellectual disability. Dr. Greenspan interviewed Ybarra,
    spoke to Ybarra’s family members, and reviewed a number
    of other materials. Dr. Greenspan’s report concluded that
    24                        YBARRA V. GITTERE
    Ybarra “meets all three prongs of the definition of mental
    retardation” under both the statutory and clinical definitions.
    Dr. Greenspan’s report first argued that Ybarra has
    significantly subaverage intellectual functioning based on
    the results of the IQ tests administered by Drs. Schmidt and
    T. Young. Dr. Greenspan opined that the 1981 IQ test
    conducted by Dr. Gutride used outdated norms and that after
    adjusting for the Flynn Effect, Ybarra’s score on the 1981 IQ
    test would be 78—close to, but not below, “the clinically-
    recommended ceiling of 75.” Dr. Greenspan also quoted one
    of Dr. Schmidt’s colleagues, who (like Dr. Schmidt)
    criticized Dr. Gutride for having an intern administer the test
    to Ybarra.6 Finally, Dr. Greenspan suggested that Dr. T.
    Young erred in using the TOMM to evaluate Ybarra for
    malingering and contended the TOMM has never been
    validated on low-IQ individuals.
    The Nevada Supreme Court unanimously denied
    Ybarra’s motion to reconsider but did not provide any
    reasons for doing so and did not strike Dr. Greenspan’s late-
    filed report from the record. Ybarra IV, 
    869 F.3d at
    1020-
    21.
    5
    In 2012, Ybarra again sought habeas relief from the
    federal district court. Ybarra v. Baker, No. 3:00-cv-0233,
    
    2013 WL 5567586
    , at *1 (D. Nev. Oct. 8, 2013). He filed a
    motion for relief from judgment under Fed. R. Civ. P.
    60(b)(6), asking the federal district court to set aside its prior
    6
    The Greenspan Report referenced reports by Drs. Mack and Warnick.
    Those doctors filed reports which were stricken by the Nevada Supreme
    Court and are not part of the state court record. See Ybarra IV, 
    869 F.3d at 1020, 1029
    .
    YBARRA V. GITTERE                    25
    judgment denying him habeas relief and consider the merits
    of his Atkins claim. 
    Id.
     The district court denied the motion
    on the merits, finding that the Nevada Supreme Court’s
    determination that Ybarra was not intellectually disabled
    was not unreasonable under AEDPA. Id. at *8.
    6
    Ybarra appealed, and we vacated the district court’s
    order. Ybarra IV, 
    869 F.3d at 1019
    . While we “express[ed]
    no view as to whether the Nevada Supreme Court’s
    intellectual disability determination was reasonable” under
    AEDPA, we found that the district court had erred when it
    “overlooked a number of instances where the Nevada
    Supreme Court contradicted the very clinical guidelines that
    it purported to apply.” 
    Id. at 1019, 1023
    . We held that
    Nevada Revised Statute section 174.098 had “incorporated
    clinical guidelines and diagnostic manuals” in defining
    intellectual disability well before the Supreme Court had
    concluded that doing so was a constitutional requirement.
    
    Id. at 1024
    . We then identified several errors in the Nevada
    Supreme Court’s reasoning:
    For example, it ignored evidence that Ybarra
    was bullied in school on the ground that it
    was irrelevant under Prong 2. The trial court
    initially expressed concern over the notion
    that “the victim [of bullying] . . . has the
    problem,” and the Nevada Supreme Court
    apparently agreed because it stated that
    evidence of bullying does “little to
    demonstrate adaptive behavior deficits.” But
    the AAMR specifically lists “gullibility” and
    an inability to “avoid[] victimization” as
    examples of limited social adaptive skills.
    26                    YBARRA V. GITTERE
    Similarly, under Prong 3, the Nevada
    Supreme Court suggested that any diagnostic
    test conducted after the age of 18 was “of
    little value.” But the AAMR specifically
    contemplates retrospective assessment when
    there are no test scores available from the
    developmental period.
    
    Id. at 1026
     (citations omitted).
    In response to the state’s argument that Ybarra’s failure
    to prove Prong 1 was dispositive, we agreed that the Nevada
    Supreme Court’s malingering determination was reasonable
    in light of Dr. T. Young’s testimony but remanded for the
    district court to examine whether that finding “was the basis
    for the Nevada Supreme Court’s determination under Prong
    1.” 
    Id.
     We observed that “the Prong 1 determination was
    unreasonable to the extent that it was based on the court’s
    lay perception that Ybarra did not ‘look like’ a disabled
    person.” 
    Id. at 1026-27
    . We explained that the “state may
    be correct that the malingering determination constitutes an
    ‘independent basis’ for the intellectual disability
    determination, thus rendering it reasonable under AEDPA.
    Alternatively, Ybarra may be correct that lay stereotypes and
    nonclinical factors infect the state court’s entire analysis,
    thus rendering it unreasonable.” 
    Id.
     (citation omitted). But
    “[r]ather than passing on these issues in the first instance, we
    [left] the task to the district court” to evaluate. 
    Id.
     Finally,
    we also concluded that the district court erred by refusing to
    consider the Greenspan Report as part of the state court
    record and directed it to consider the Report on remand. 
    Id. at 1027
    .
    YBARRA V. GITTERE                     27
    7
    On remand, the district court again took up the question
    of Ybarra’s intellectual disability and found the Nevada
    Supreme Court had not unreasonably determined Ybarra
    failed to prove the first prong. The district court concluded
    that the Nevada Supreme Court had not ruled as it did
    because Ybarra did not “look like a disabled person.”
    Rather, the state courts found that the only sub-75 IQ scores
    in the record were invalid because of Dr. Schmidt’s
    disclaimer as to the accuracy of his results and Dr. T.
    Young’s testimony about the likelihood that Ybarra was
    malingering. The state courts also credited Dr. Gutride’s
    1981 IQ score and rejected Dr. Schmidt’s criticism of that
    test because (1) the AAMR manual did not recommend
    adjusting for the Flynn Effect, (2) an adjustment would still
    leave Ybarra with an IQ of 78, and (3) Dr. Schmidt admitted
    he “really could not talk about” the 1981 score’s validity.
    Finally, the district court noted concerns with Dr.
    Greenspan’s report that called into doubt his analysis of this
    prong, including the fact that Dr. Greenspan filed two
    versions of his report because the first one contained errors.
    DISCUSSION
    We are now asked to review the federal district court’s
    analysis of the questions we remanded for it to consider,
    namely, whether lay stereotypes and nonclinical factors
    infected the state court’s entire analysis and how the
    Greenspan Report should factor into that analysis. We
    review de novo the federal district court’s review of the state
    court’s decision. Ybarra IV, 
    869 F.3d at 1023
    . However,
    under AEDPA, we may not grant Ybarra habeas relief unless
    the state court’s decision “was based on an unreasonable
    determination of the facts in light of the evidence presented
    28                    YBARRA V. GITTERE
    in the State court proceeding.” § 2254(d)(2). A state court’s
    factual determination of his intellectual functioning is not
    unreasonable simply because we would have reached a
    different conclusion. Dixon v. Shinn, 
    33 F.4th 1050
    , 1054
    (9th Cir. 2022). “A petitioner challenging the substance of
    the state court’s findings must show ‘that an appellate panel,
    applying the normal standards of appellate review, could not
    reasonably conclude that the finding is supported by the
    record.’” Prescott v. Santoro, 
    53 F.4th 470
    , 479 (9th Cir.
    2022) (quoting Hibbler v. Benedetti, 
    693 F.3d 1140
    , 1146
    (9th Cir. 2012)). This “daunting standard” is “satisfied in
    relatively few cases” but “is not impossible to meet.” Taylor
    v. Maddox, 
    366 F.3d 992
    , 1000 (9th Cir. 2004), overruled on
    other grounds by Cullen v. Pinholster, 
    563 U.S. 170
    , 185
    (2011).
    If the state court’s determination of the facts was
    unreasonable, we must then review Ybarra’s Atkins claim de
    novo before we may grant habeas relief. See Maxwell v. Roe,
    
    628 F.3d 486
    , 494-95 (9th Cir. 2010). Even if Ybarra’s
    claim has merit, the United States Supreme Court has
    recently suggested that a state prisoner is “never entitled to
    habeas relief” unless he persuades the court that both “law
    and justice require [it].” Shinn v. Ramirez, 
    142 S. Ct. 1718
    ,
    1731 (2022) (alteration in original) (quoting Brown v.
    Davenport, 
    142 S. Ct. 1510
    , 1524 (2022)).
    I
    To prevail on his petition for habeas relief, Ybarra must
    show that the Nevada Supreme Court unreasonably
    determined that he failed to prove that (1) he had
    significantly subaverage intellectual functioning; (2) he
    suffered from adaptive behavioral deficits; and (3) those
    symptoms manifested prior to age 18. Ybarra fails to make
    YBARRA V. GITTERE                     29
    a showing that he had significantly subaverage intellectual
    functioning. That is dispositive and defeats the basis of his
    habeas claim.
    Ybarra’s first argument that the determination is
    unreasonable rests on a narrow reading of the Nevada
    Supreme Court’s decision. Ybarra argues that the court
    unreasonably found that the 1981 IQ test administered by Dr.
    Gutride was of “little value” because it was conducted well
    after Ybarra turned 18 and refused to consider any evidence
    from outside the developmental period. Ybarra contends
    that because we have already held that it would be an error
    to disregard any testing conducted outside the
    developmental period, the Nevada Supreme Court’s
    determination of Prong 1 is unreasonable. Ybarra IV, 
    869 F.3d at 1026
    . Ybarra claims that while the state trial court
    may have relied on the 1981 IQ test, the Nevada Supreme
    Court declined to adopt that logic, and so could not have
    relied on the 1981 test to find that Ybarra had failed to prove
    Prong 1. Accordingly, Ybarra argues that the federal district
    court erred in concluding that the Nevada Supreme Court
    had “affirm[ed] the lower court’s reliance on the 1981 IQ
    test that yielded a score of 86.”
    This argument is belied by a fair reading of the Nevada
    Supreme Court’s opinion. The sentences in the opinion that
    Ybarra repeatedly cites are in fact only part of that court’s
    response to Ybarra’s contention that the trial court erred by
    (1) “disregarding” Dr. Schmidt’s IQ testing; (2) concluding
    that the 1981 test “was valid”; and (3) failing to account for
    the Flynn Effect. Ybarra II, 
    247 P.3d at 281
    . In fact, the
    Nevada Supreme Court gave “three reasons” for rejecting
    Ybarra’s arguments. 
    Id. at 282
    . First, the court explicitly
    rejected Ybarra’s argument that the trial court had erred in
    crediting the 1981 IQ test over Dr. Schmidt’s testing:
    30                   YBARRA V. GITTERE
    [T]he district court did not disregard Dr.
    Schmidt’s testimony regarding the Flynn
    effect. Rather, the court found the testimony
    incredible considering (a) other sources that
    either rejected the theory or did not demand
    adjustments in IQ scores to account for it; and
    (b) other evidence in the record supporting
    the validity of the 1981 IQ score, including
    evaluations from mental health professionals
    and Ybarra’s military records reporting that
    he was of dull-normal to borderline
    intelligence. And although the district court
    was “not convinced [that] the scientific
    community is prepared to adjust the scores
    according to the Flynn effect,” it nevertheless
    considered the Flynn effect and concluded
    that an adjustment for that effect reduced the
    1981 IQ score to 78, which is outside the
    range of mental retardation . . . . [That]
    calculation was not without foundation.
    
    Id.
     (emphasis added).
    Only then did the Nevada Supreme Court proceed to give
    two other, independent reasons for rejecting Ybarra’s
    arguments. The second reason it gave for affirming the trial
    court’s finding was that, based on “Ybarra’s school and other
    records, his writings, and evidence that he was malingering”
    the “record as a whole (irrespective of the various IQ test
    scores) portrays Robert Ybarra as a person who does not
    have significant subaverage intellectual functioning.” 
    Id.
    Finally, the Nevada Supreme Court said that it “need not
    decide the relevance, if any, of the Flynn effect and the
    YBARRA V. GITTERE                    31
    necessity of adjusting the 1981 IQ score” because the 1981
    IQ test occurred well after Ybarra turned 18. 
    Id. at 282-83
    .
    Even if this final reason was an unreasonable deviation
    from the clinical guidelines, see Ybarra IV, 
    869 F.3d at 1026
    ,
    the first reason was not. The Nevada Supreme Court found
    that the trial court had not erred in finding Dr. Schmidt’s
    criticism of the 1981 IQ test “incredible” and found the
    “validity” of that test was supported by the record. Ybarra
    II, 
    247 P.3d at 282
    . And it affirmed the trial court’s finding
    that, even accounting for the Flynn Effect, Ybarra’s 1981 IQ
    score was still not below 75—which Ybarra concedes is
    required to show significantly subaverage intellectual
    functioning. 
    Id.
     This was not unreasonable. Dr. Schmidt
    admitted his own tests might underestimate Ybarra’s “actual
    intellectual functioning.” Dr. T. Young defended the
    validity of the 1981 IQ score in his testimony and criticized
    Dr. Schmidt’s testing. The state court was free to “credit one
    expert over another.” Apelt, 
    878 F.3d at 837
    .
    The Nevada Supreme Court’s second reason for
    rejecting Ybarra’s criticism of the 1981 IQ test was also
    reasonable. As the court explained:
    [T]he district court did not rely solely on the
    1981 IQ test to determine that Ybarra had not
    proven that he suffers from significant
    subaverage intellectual functioning. As
    explained above, the district court also
    looked to Ybarra’s school and other records,
    his writings, and evidence that he was
    malingering. In fact, the district court
    expressly observed in its order that “[t]he
    record as a whole (irrespective of the various
    IQ test scores) portrays Robert Ybarra as a
    32                   YBARRA V. GITTERE
    person who does not have significant
    subaverage intellectual functioning now or
    during his developmental years.”
    Ybarra II, 
    247 P.3d at 282
    . We were “troubled by this
    statement” out of concern that it may have been “based on
    the court’s lay perception that Ybarra did not ‘look like’ a
    disabled person.” Ybarra IV, 
    869 F.3d at 1026-27
    .
    However, we also suggested that to the extent that this
    finding was informed by a determination that Ybarra was
    malingering, it was reasonable. 
    Id. at 1026
    .
    As the federal district court noted on remand, the
    quotation about the “record as a whole” is taken from a
    section in the trial court decision titled “Malingering and
    Other Evidence of Intellectual Functioning.” That section of
    the state trial court’s decision notes that, when asked if he
    saw evidence of malingering in records he reviewed to
    prepare for his testimony, Dr. Schmidt mentioned only Dr.
    T. Young’s report and “some issues” from the state
    correctional medical center where Ybarra was evaluated for
    competency. The state trial court then criticizes Dr. Schmidt
    for ignoring numerous other pieces of evidence which
    suggest malingering, including Ybarra’s 1979 and 1981
    attempts to manipulate the MMPI, his 1991 statement about
    “having to act crazy” in prison, and the conclusions of other
    doctors that Ybarra was faking psychological symptoms. It
    also discusses in passing Ybarra’s ability to “manipulate
    health care professionals, attorneys, play scrabble,
    backgammon, racquetball and volleyball, and his ability to
    type, read medical literature, [and] write coherent
    meaningful letters.” Finally, the trial court closed this
    section by noting that Dr. T. Young’s testing, including the
    TOMM test, suggested that Ybarra was malingering.
    YBARRA V. GITTERE                     33
    Taken in context, it is clear the Nevada courts did not
    base their Prong 1 determination on a “lay perception that
    Ybarra did not ‘look like’ a disabled person.” Ybarra IV,
    
    869 F.3d at 1027
    . Parts of the trial court’s decision arguably
    make this error, such as by discussing Ybarra’s ability to
    play games and write letters. Ybarra II, 
    247 P.3d at 280
    ; see
    also Moore v. Texas (Moore II), 
    139 S. Ct. 666
    , 671 (2019)
    (criticizing the appellate court for considering adaptive
    strengths developed in prison). But most of the section of
    the state trial court’s decision in question (1) finds that Dr.
    Schmidt’s testimony and IQ testing is not credible because
    he failed to adequately consider evidence that Ybarra was
    malingering and (2) cites Dr. T. Young’s testimony to
    conclude Ybarra was malingering.              This was not
    unreasonable; a finder of fact may consider the data an
    expert relied on in reaching an opinion, see FED. R. EVID.
    705, and “reject” expert testimony based on “the reasons
    given for the opinion” and “the other evidence in the case.”
    See NINTH CIR. MODEL CRIM. JURY INSTR. § 3.14 (2023); see
    also Ochoa v. Davis, 
    50 F.4th 865
    , 903-04 (9th Cir. 2022)
    (citing petitioner’s school records, social activities, and
    criminal conduct in concluding he had failed to show
    significant adaptive deficits). Courts are not required to
    credit expert testimony. See Ochoa, 50 F.4th at 905; Apelt,
    
    878 F.3d at 837-38
    ; Cain v. Chappell, 
    870 F.3d 1003
    , 1023-
    24 (9th Cir. 2017).
    Ybarra’s second argument is that reliance on anything
    other than expert testimony amounts to a reliance on
    “stereotypes” about intellectual disability. For example,
    Ybarra asserts repeatedly that the Nevada Supreme Court
    erred in relying on a “wealth of other evidence” in
    concluding that Ybarra was malingering, because “none of
    the experts relied” on it in reaching a conclusion about
    34                    YBARRA V. GITTERE
    intellectual functioning. But this is simply incorrect: every
    expert, including Ybarra’s experts, testified that, in forming
    their conclusions, they had interviewed Ybarra, reviewed
    records about Ybarra, or both. To the extent Ybarra’s
    experts relied on faulty evidence (i.e., false statements by
    Ybarra during testing) or failed to consider evidence (i.e.,
    records suggesting Ybarra was not intellectually disabled) it
    was not unreasonable to find that their conclusions were
    invalid—especially since the trial court also “considered the
    TOMM results.” Ybarra II, 
    247 P.3d at 283
    . A court’s
    intellectual disability determination must be informed by
    clinical guidance, but “‘the views of medical experts’ do not
    ‘dictate’” the outcome. Moore v. Texas (Moore I), 
    581 U.S. 1
    , 13 (2017) (quotation omitted).
    Finally, even if Ybarra is correct that the Nevada
    Supreme Court gave little weight to both (1) the 1981 IQ test
    and (2) the TOMM test, the Prong 1 finding is still not
    unreasonable. As discussed, it was Ybarra’s burden to prove
    Prong 1 by a preponderance of the evidence, which requires
    an IQ score of 75 or below. See 
    Nev. Rev. Stat. § 174.098
    (5)(b). There are only two such scores in the record:
    Dr. T. Young’s, which he disclaimed as invalid, and Dr.
    Schmidt’s score. The Nevada Supreme Court affirmed the
    trial court’s finding that Dr. Schmidt’s testimony was not
    credible, see Ybarra II, 
    247 P.3d at 279, 282, 284
    , and that
    finding is likely entitled to double deference, see 
    id. at 276
    (“Matters of credibility . . . remain . . . within the [trial]
    court’s discretion.”); and was not unreasonable for the
    reasons already discussed. Thus, even if the Nevada
    Supreme Court gave little weight to the 1981 IQ score, the
    absence of any valid sub-75 IQ would still mean Ybarra
    failed to meet his burden.
    YBARRA V. GITTERE                      35
    Dr. Greenspan’s report adds little in terms of intellectual
    functioning. Dr. Greenspan recalculated the impact of the
    Flynn Effect on the 1981 IQ test, and concluded that even
    accounting for that effect, Ybarra’s IQ was 78—essentially
    confirming that the trial court’s calculation was correct. Dr.
    Greenspan’s report otherwise rehashes criticisms that were
    already made by Dr. Schmidt: he repeats Dr. Schmidt’s
    critiques of the 1981 IQ score and criticizes Dr. T. Young’s
    use of the TOMM test for the same reasons that Dr. Schmidt
    did. Finally, Dr. Greenspan’s report says virtually nothing
    about the other evidence that Ybarra was malingering. As a
    result, Ybarra’s Prong 1 argument still fails because no valid
    IQ test has shown significantly subaverage intellectual
    functioning. Because we find that the Nevada Supreme
    Court’s Prong 1 determination was reasonable, we do not
    consider Prongs 2 or 3 and Ybarra’s petition must be denied.
    See Apelt, 
    878 F.3d at 837
     (“To prevail on his Atkins claim,
    [the petitioner] must meet all three prongs of the test for
    intellectual disability.”).
    CONCLUSION
    Because the Nevada Supreme Court was not
    unreasonable in finding that Ybarra had failed to prove he is
    intellectually disabled by a preponderance of the evidence,
    the district court’s denial of his federal petition for a writ of
    habeas corpus was correct.
    AFFIRMED.