(Slip Opinion)              OCTOBER TERM, 2016                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                              MOORE v. TEXAS

CERTIORARI TO THE COURT OF CRIMINAL APPEALS OF TEXAS

  No. 15–797.      Argued November 29, 2016—Decided March 28, 2017
Petitioner Moore was convicted of capital murder and sentenced to
  death for fatally shooting a store clerk during a botched robbery that
  occurred when Moore was 20 years old. A state habeas court subse-
  quently determined that, under Atkins v. Virginia, 536 U. S. 304, and
  Hall v. Florida, 572 U. S. ___, Moore qualified as intellectually disa-
  bled and that his death sentence therefore violated the Eighth
  Amendment’s proscription of “cruel and unusual punishments.” The
  court consulted current medical diagnostic standards—the 11th edi-
  tion of the American Association on Intellectual and Developmental
  Disabilities clinical manual (AAIDD–11) and the 5th edition of the
  Diagnostic and Statistical Manual of Mental Disorders published by
  the American Psychiatric Association. The habeas court followed the
  generally accepted intellectual-disability definition, which identifies
  three core elements: (1) intellectual-functioning deficits, (2) adaptive
  deficits, and (3) the onset of these deficits while still a minor. Moore’s
  IQ scores, the court determined, established subaverage intellectual
  functioning. The court credited six scores, the average of which
  (70.66) indicated mild intellectual disability. And relying on testimo-
  ny from mental-health professionals, the court found significant
  adaptive deficits in all three skill sets (conceptual, social, and practi-
  cal). Based on its findings, the habeas court recommended to the
  Texas Court of Criminal Appeals (CCA) that Moore be granted relief.
  The CCA declined to adopt the judgment recommended by the habeas
  court. The CCA held instead that the habeas court erred by not fol-
  lowing the CCA’s 2004 decision in Ex parte Briseno, 135 S. W. 3d 1,
  which adopted the definition of, and standards for assessing, intellec-
  tual disability contained in the 1992 (ninth) edition of the American
  Association on Mental Retardation manual (AAMR–9), predecessor to
  the current AAIDD–11 manual. Briseno also incorporated the
2                          MOORE v. TEXAS

                                Syllabus

 AAMR–9’s requirement that adaptive deficits must be “related” to in-
 tellectual-functioning deficits, and it recited, without citation to any
 medical or judicial authority, seven evidentiary factors relevant to
 the intellectual-disability inquiry. Based on only two of Moore’s IQ
 scores (of 74 and 78), the CCA concluded that Moore had not shown
 significantly subaverage intellectual functioning. And even if he had,
 the CCA continued, his adaptive strengths undercut any adaptive
 weaknesses. The habeas court also failed, the CCA determined, to
 inquire into relatedness. Among alternative causes for Moore’s adap-
 tive deficits, the CCA suggested, were an abuse-filled childhood, un-
 diagnosed learning disorders, multiple elementary-school transfers,
 racially motivated harassment and violence at school, and a history
 of academic failure, drug abuse, and absenteeism. Briseno’s seven
 evidentiary factors, the CCA further determined, weighed against
 finding that Moore had satisfied the relatedness requirement.
Held: By rejecting the habeas court’s application of medical guidance
 and by following the Briseno standard, including the nonclinical
 Briseno factors, the CCA’s decision does not comport with the Eighth
 Amendment and this Court’s precedents. Pp. 9–18.
    (a) The Eighth Amendment, which “ ‘reaffirms the duty of the gov-
 ernment to respect the dignity of all persons,’ ” Hall, 572 U. S., at ___,
 prohibits the execution of any intellectually disabled individual, At-
 kins, 536 U. S., at 321. While Atkins and Hall left to the States “the
 task of developing appropriate ways to enforce” the restriction on ex-
 ecuting the intellectually disabled, Hall, 572 U. S., at ___ (internal
 quotation marks omitted), States’ discretion is not “unfettered,” id.,
 at ___, and must be “informed by the medical community’s diagnostic
 framework,” id., at ___–___. Relying on the most recent (and still
 current) versions of the leading diagnostic manuals, the Court con-
 cluded in Hall that Florida had “disregard[ed] established medical
 practice,” id., at ___, and had parted ways with practices and trends
 in other States, id., at ___–___. Hall indicated that being informed by
 the medical community does not demand adherence to everything
 stated in the latest medical guide. But neither does precedent license
 disregard of current medical standards. Pp. 9–10.
    (b) The CCA’s conclusion that Moore’s IQ scores established that he
 is not intellectually disabled is irreconcilable with Hall, which in-
 structs that, where an IQ score is close to, but above, 70, courts must
 account for the test’s “standard error of measurement.” See 572
 U. S., at ___–___, ___–___. Because the lower range of Moore’s ad-
 justed IQ score of 74 falls at or below 70, the CCA had to move on to
 consider Moore’s adaptive functioning. Pp. 10–12.
    (c) The CCA’s consideration of Moore’s adaptive functioning also
 deviated from prevailing clinical standards and from the older clini-
                      Cite as: 581 U. S. ____ (2017)                     3

                                Syllabus

  cal standards the CCA deemed applicable. Pp. 12–16.
       (1) The CCA overemphasized Moore’s perceived adaptive
  strengths—living on the streets, mowing lawns, and playing pool for
  money—when the medical community focuses the adaptive-
  functioning inquiry on adaptive deficits. The CCA also stressed
  Moore’s improved behavior in prison, but clinicians caution against
  reliance on adaptive strengths developed in controlled settings.
  Pp. 12–13.
       (2) The CCA further concluded that Moore’s record of academic
  failure, along with a history of childhood abuse and suffering, de-
  tracted from a determination that his intellectual and adaptive defi-
  cits were related. The medical community, however, counts traumat-
  ic experiences as risk factors for intellectual disability. The CCA also
  departed from clinical practice by requiring Moore to show that his
  adaptive deficits were not related to “a personality disorder.” Men-
  tal-health professionals recognize that intellectually disabled people
  may have other co-existing mental or physical impairments, includ-
  ing, e.g., attention-deficit/hyperactivity disorder, depressive and bipo-
  lar disorders, and autism. Pp. 13–14.
       (3) The CCA’s attachment to the seven Briseno evidentiary fac-
  tors further impeded its assessment of Moore’s adaptive functioning.
  By design and in operation, the lay perceptions advanced by Briseno
  “creat[e] an unacceptable risk that persons with intellectual disabil-
  ity will be executed.” Hall, 572 U. S., at ___. The medical profession
  has endeavored to counter lay stereotypes, and the Briseno factors
  are an outlier, in comparison both to other States’ handling of intel-
  lectual-disability pleas and to Texas’ own practices in contexts other
  than the death penalty. Pp. 14–16.
     (d) States have some flexibility, but not “unfettered discretion,” in
  enforcing Atkins’ holding, Hall, 572 U. S., at ___, and the medical
  community’s current standards, reflecting improved understanding
  over time, constrain States’ leeway in this area. Here, the habeas
  court applied current medical standards in reaching its conclusion,
  but the CCA adhered to the standard it laid out in Briseno, including
  the nonclinical Briseno factors. The CCA therefore failed adequately
  to inform itself of the “medical community’s diagnostic framework,”
  Hall, 572 U. S., at ___–___. Because Briseno pervasively infected the
  CCA’s analysis, the decision of that court cannot stand. Pp. 17–18.
470 S. W. 3d 481, vacated and remanded.

  GINSBURG, J., delivered the opinion of the Court, in which KENNEDY,
BREYER, SOTOMAYOR, and KAGAN, JJ., joined. ROBERTS, C. J., filed a
dissenting opinion, in which THOMAS and ALITO, JJ., joined.
                        Cite as: 581 U. S. ____ (2017)                              1

                             Opinion of the Court

     NOTICE: This opinion is subject to formal revision before publication in the
     preliminary print of the United States Reports. Readers are requested to
     notify the Reporter of Decisions, Supreme Court of the United States, Wash-
     ington, D. C. 20543, of any typographical or other formal errors, in order
     that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                   _________________

                                   No. 15–797
                                   _________________


    BOBBY JAMES MOORE, PETITIONER v. TEXAS
           ON WRIT OF CERTIORARI TO THE COURT OF

                CRIMINAL APPEALS OF TEXAS

                                [March 28, 2017]


  JUSTICE GINSBURG delivered the opinion of the Court.
  Bobby James Moore fatally shot a store clerk during a
botched robbery. He was convicted of capital murder and
sentenced to death. Moore challenged his death sentence
on the ground that he was intellectually disabled and
therefore exempt from execution. A state habeas court
made detailed factfindings and determined that, under
this Court’s decisions in Atkins v. Virginia, 536 U. S. 304
(2002), and Hall v. Florida, 572 U. S. ___ (2014), Moore
qualified as intellectually disabled. For that reason, the
court concluded, Moore’s death sentence violated the
Eighth Amendment’s proscription of “cruel and unusual
punishments.” The habeas court therefore recommended
that Moore be granted relief.
  The Texas Court of Criminal Appeals (CCA)1 declined to
adopt the judgment recommended by the state habeas
court.2 In the CCA’s view, the habeas court erroneously
——————
  1 The CCA is Texas’ court of last resort in criminal cases. See Tex.

Const., Art. 5, §5.
  2 Under Texas law, the CCA, not the court of first instance, is “the

ultimate factfinder” in habeas corpus proceedings. Ex parte Reed, 271
S. W. 3d 698, 727 (Tex. Crim. App. 2008); see Ex parte Moore, 470
S. W. 3d 481, 489 (Tex. Crim. App. 2015).
2                     MOORE v. TEXAS

                      Opinion of the Court

employed intellectual-disability guides currently used in
the medical community rather than the 1992 guides
adopted by the CCA in Ex parte Briseno, 135 S. W. 3d 1
(2004). See Ex parte Moore, 470 S. W. 3d 481, 486–487
(2015). The appeals court further determined that the
evidentiary factors announced in Briseno “weigh[ed]
heavily” against upsetting Moore’s death sentence. 470
S. W. 3d, at 526.
   We vacate the CCA’s judgment. As we instructed in
Hall, adjudications of intellectual disability should be
“informed by the views of medical experts.” 572 U. S., at
___ (slip op., at 19); see id., at ___ (slip op., at 7). That
instruction cannot sensibly be read to give courts leave to
diminish the force of the medical community’s consensus.
Moreover, the several factors Briseno set out as indicators
of intellectual disability are an invention of the CCA un-
tied to any acknowledged source. Not aligned with the
medical community’s information, and drawing no
strength from our precedent, the Briseno factors “creat[e]
an unacceptable risk that persons with intellectual dis-
ability will be executed,” 572 U. S., at ___ (slip op., at 1).
Accordingly, they may not be used, as the CCA used them,
to restrict qualification of an individual as intellectually
disabled.
                              I
  In April 1980, then-20-year-old Bobby James Moore and
two others were engaged in robbing a grocery store.
Ex parte Moore, 470 S. W. 3d 481, 490–491 (Tex. Crim.
App. 2015); App. 58. During the episode, Moore fatally
shot a store clerk. 470 S. W. 3d, at 490. Some two months
later, Moore was convicted and sentenced to death. See
id., at 492. A federal habeas court later vacated that
sentence based on ineffective assistance of trial counsel,
see Moore v. Collins, 1995 U. S. Dist. LEXIS 22859, *35
(SD Tex., Sept. 29, 1995), and the Fifth Circuit affirmed,
                  Cite as: 581 U. S. ____ (2017)            3

                      Opinion of the Court

see Moore v. Johnson, 194 F. 3d 586, 622 (1999). Moore
was resentenced to death in 2001, and the CCA affirmed
on direct appeal. See Moore v. State, 2004 WL 231323, *1
(Jan. 14, 2004), cert. denied, 543 U. S. 931 (2004).
   Moore subsequently sought state habeas relief. In 2014,
the state habeas court conducted a two-day hearing on
whether Moore was intellectually disabled. See Ex parte
Moore, No. 314483–C (185th Jud. Dist., Harris Cty., Tex.,
Feb. 6, 2015), App. to Pet. for Cert. 129a. The court re-
ceived affidavits and heard testimony from Moore’s family
members, former counsel, and a number of court-
appointed mental-health experts. The evidence revealed
that Moore had significant mental and social difficulties
beginning at an early age. At 13, Moore lacked basic
understanding of the days of the week, the months of the
year, and the seasons; he could scarcely tell time or com-
prehend the standards of measure or the basic principle
that subtraction is the reverse of addition. Id., at 187a.
At school, because of his limited ability to read and write,
Moore could not keep up with lessons. Id., at 146a, 182a–
183a. Often, he was separated from the rest of the class
and told to draw pictures. Ibid. Moore’s father, teachers,
and peers called him “stupid” for his slow reading and
speech. Id., at 146a, 183a. After failing every subject in
the ninth grade, Moore dropped out of high school. Id., at
188a. Cast out of his home, he survived on the streets,
eating from trash cans, even after two bouts of food poi-
soning. Id., at 192a–193a.
   In evaluating Moore’s assertion of intellectual disability,
the state habeas court consulted current medical diagnos-
tic standards, relying on the 11th edition of the American
Association on Intellectual and Developmental Disabilities
(AAIDD) clinical manual, see AAIDD, Intellectual Disabil-
ity: Definition, Classification, and Systems of Supports
(2010) (hereinafter AAIDD–11), and on the 5th edition of
the Diagnostic and Statistical Manual of Mental Disorders
4                         MOORE v. TEXAS

                          Opinion of the Court

published by the American Psychiatric Association (APA),
see APA, Diagnostic and Statistical Manual of Mental
Disorders (2013) (hereinafter DSM–5). App. to Pet. for
Cert. 150a–151a, 202a. The court followed the generally
accepted, uncontroversial intellectual-disability diagnos-
tic definition, which identifies three core elements:
(1) intellectual-functioning deficits (indicated by an IQ
score “approximately two standard deviations below the
mean”—i.e., a score of roughly 70—adjusted for “the
standard error of measurement,” AAIDD–11, at 27); (2)
adaptive deficits (“the inability to learn basic skills and
adjust behavior to changing circumstances,” Hall v. Flor-
ida, 572 U. S. ___, ___ (2014) (slip op., at 8)); and (3) the
onset of these deficits while still a minor. See App. to Pet.
for Cert. 150a (citing AAIDD–11, at 1). See also Hall, 572
U. S., at ___ (slip op., at 8).3
   Moore’s IQ scores, the habeas court determined, estab-
lished subaverage intellectual functioning. The court
credited six of Moore’s IQ scores, the average of which
(70.66) indicated mild intellectual disability. App. to Pet.
for Cert. 167a–170a.4 And relying on testimony from
several mental-health experts, the habeas court found
significant adaptive deficits. In determining the signifi-
cance of adaptive deficits, clinicians look to whether an
individual’s adaptive performance falls two or more stand-
ard deviations below the mean in any of the three adaptive
skill sets (conceptual, social, and practical). See AAIDD–
11, at 43. Moore’s performance fell roughly two standard
deviations below the mean in all three skill categories.
App. to Pet. for Cert. 200a–201a. Based on this evidence,
the state habeas court recommended that the CCA reduce
——————
    3 The
       third element is not at issue here.
    4 The
        habeas court considered a seventh score (of 59 on a WAIS–IV
test administered in 2013) elsewhere in its opinion, see App. to Pet. for
Cert. 170a–172a, but did not include that score in the calculation of
Moore’s average IQ score, see id., at 170a.
                     Cite as: 581 U. S. ____ (2017)                    5

                          Opinion of the Court

Moore’s sentence to life in prison or grant him a new trial
on intellectual disability. See id., at 203a.
   The CCA rejected the habeas court’s recommendations
and denied Moore habeas relief. See 470 S. W. 3d 481. At
the outset of its opinion, the CCA reaffirmed Ex parte
Briseno, 135 S. W. 3d 1 (Tex. Crim. App. 2004), as para-
mount precedent on intellectual disability in Texas capital
cases. See 470 S. W. 3d, at 486–487. Briseno adopted the
definition of, and standards for assessing, intellectual
disability contained in the 1992 (ninth) edition of the
American Association on Mental Retardation (AAMR)
manual, predecessor to the current AAIDD–11 manual.
See 135 S. W. 3d, at 7 (citing AAMR, Mental Retardation:
Definition, Classification, and Systems of Supports (9th
ed. 1992) (hereinafter AAMR–9)).
   Briseno incorporated the AAMR–9’s requirement that
adaptive deficits be “related” to intellectual-functioning
deficits. 135 S. W. 3d, at 7 (quoting AAMR–9, at 25).5 To
determine whether a defendant has satisfied the related-
ness requirement, the CCA instructed in this case, Texas
courts should attend to the “seven evidentiary factors”
first set out in Briseno. 470 S. W. 3d, at 489.6 No citation to
——————
   5 This relatedness requirement, the CCA noted, is retained in the

DSM–5. See 470 S. W. 3d, at 487, n. 5 (citing DSM–5, at 38).
   6 The seven “Briseno factors” are:

●	 “Did those who knew the person best during the developmental
   stage—his family, friends, teachers, employers, authorities—think he
   was mentally retarded at that time, and, if so, act in accordance with
   that determination?
●	 “Has the person formulated plans and carried them through or is his
   conduct impulsive?
●	 “Does his conduct show leadership or does it show that he is led
   around by others?
●	 “Is his conduct in response to external stimuli rational and appropri-
   ate, regardless of whether it is socially acceptable?
●	 “Does he respond coherently, rationally, and on point to oral or
   written questions or do his responses wander from subject to subject?
●	 “Can the person hide facts or lie effectively in his own or others’
6                          MOORE v. TEXAS

                           Opinion of the Court

any authority, medical or judicial, accompanied the
Briseno court’s recitation of the seven factors. See 135
S. W. 3d, at 8–9.
    The habeas judge erred, the CCA held, by “us[ing] the
most current position, as espoused by AAIDD, regarding
the diagnosis of intellectual disability rather than the test
. . . in Briseno.” 470 S. W. 3d, at 486. This Court’s deci-
sion in Atkins v. Virginia, 536 U. S. 304 (2002), the CCA
emphasized, “left it to the States to develop appropriate
ways to enforce the constitutional restriction” on the exe-
cution of the intellectually disabled. 470 S. W. 3d, at 486.
Thus, even though “[i]t may be true that the AAIDD’s and
APA’s positions regarding the diagnosis of intellectual
disability have changed since Atkins and Briseno,” the
CCA retained Briseno’s instructions, both because of “the
subjectivity surrounding the medical diagnosis of intellec-
tual disability” and because the Texas Legislature had
not displaced Briseno with any other guideposts. 470
S. W. 3d, at 486–487. The Briseno inquiries, the court
said, “remai[n] adequately ‘informed by the medical com-
munity’s diagnostic framework.’ ” 470 S. W. 3d, at 487
(quoting Hall, 572 U. S., at ___ (slip op., at 19–20)).
    Employing Briseno, the CCA first determined that
Moore had failed to prove significantly subaverage intel-
lectual functioning. 470 S. W. 3d, at 514–519. Rejecting
as unreliable five of the seven IQ tests the habeas court
had considered, the CCA limited its appraisal to Moore’s
scores of 78 in 1973 and 74 in 1989. Id., at 518–519. The
court then discounted the lower end of the standard-error
range associated with those scores. Id., at 519; see infra,
at 10–11 (describing standard error of measurement).
——————
     interests?
●	   “Putting aside any heinousness or gruesomeness surrounding the
     capital offense, did the commission of that offense require fore-
     thought, planning, and complex execution of purpose?” Briseno, 135
     S. W. 3d, at 8–9.
                   Cite as: 581 U. S. ____ (2017)              7

                       Opinion of the Court

Regarding the score of 74, the court observed that Moore’s
history of academic failure, and the fact that he took the
test while “exhibit[ing] withdrawn and depressive behav-
ior” on death row, might have hindered his performance.
470 S. W. 3d, at 519. Based on the two scores, but not on
the lower portion of their ranges, the court concluded that
Moore’s scores ranked “above the intellectually disabled
range” (i.e., above 70). Ibid.; see id., at 513.
   “Even if [Moore] had proven that he suffers from signifi-
cantly sub-average general intellectual functioning,” the
court continued, he failed to prove “significant and related
limitations in adaptive functioning.” Id., at 520. True, the
court acknowledged, Moore’s and the State’s experts
agreed that Moore’s adaptive-functioning test scores fell
more than two standard deviations below the mean. Id.,
at 521; see supra, at 4. But the State’s expert ultimately
discounted those test results because Moore had “no expo-
sure” to certain tasks the testing included, “such as writ-
ing a check and using a microwave oven.” 470 S. W. 3d, at
521–522. Instead, the expert emphasized Moore’s adap-
tive strengths in school, at trial, and in prison. Id., at
522–524.
   The CCA credited the state expert’s appraisal. Id., at
524. The habeas court, the CCA concluded, had erred by
concentrating on Moore’s adaptive weaknesses. Id., at
489. Moore had demonstrated adaptive strengths, the
CCA spelled out, by living on the streets, playing pool and
mowing lawns for money, committing the crime in a so-
phisticated way and then fleeing, testifying and represent-
ing himself at trial, and developing skills in prison. Id., at
522–523. Those strengths, the court reasoned, undercut
the significance of Moore’s adaptive limitations. Id., at
524–525.
   The habeas court had further erred, the CCA deter-
mined, by failing to consider whether any of Moore’s adap-
tive deficits were related to causes other than his intellectual-
8                     MOORE v. TEXAS

                     Opinion of the Court

functioning deficits. Id., at 488, 526. Among alterna-
tive causes for Moore’s adaptive deficits, the CCA suggested,
were an abuse-filled childhood, undiagnosed learning
disorders, multiple elementary-school transfers, racially
motivated harassment and violence at school, and a his-
tory of academic failure, drug abuse, and absenteeism. Ibid.
Moore’s significant improvement in prison, in the CCA’s
view, confirmed that his academic and social difficulties
were not related to intellectual-functioning deficits. Ibid.
The court then examined each of the seven Briseno evi-
dentiary factors, see supra, at 5–6, and n. 6, concluding
that those factors “weigh[ed] heavily” against finding that
Moore had satisfied the relatedness requirement. 470
S. W. 3d, at 526–527.
   Judge Alcala dissented. Atkins and Hall, she would
have held, require courts to consult current medical
standards to determine intellectual disability.          470
S. W. 3d, at 530. She criticized the majority for relying on
manuals superseded in the medical community, id., at
530–534, 536–539, and for disregarding the habeas court’s
credibility determinations, id., at 535–536, 538–539.
Judge Alcala questioned the legitimacy of the seven
Briseno factors, recounting wide criticism of the factors
and explaining how they deviate from the current medical
consensus. See 470 S. W. 3d, at 529–530, and n. 5. Most
emphatically, she urged, the CCA “must consult the medi-
cal community’s current views and standards in determin-
ing whether a defendant is intellectually disabled”; “reli-
ance on . . . standard[s] no longer employed by the medical
community,” she objected, “is constitutionally unaccept-
able.” Id., at 533.
   We granted certiorari to determine whether the CCA’s
adherence to superseded medical standards and its reli-
ance on Briseno comply with the Eighth Amendment and
this Court’s precedents. 578 U. S. ___ (2016).
                  Cite as: 581 U. S. ____ (2017)              9

                      Opinion of the Court

                                II
   The Eighth Amendment prohibits “cruel and unusual
punishments,” and “reaffirms the duty of the government
to respect the dignity of all persons,” Hall, 572 U. S., at
___ (slip op., at 5) (quoting Roper v. Simmons, 543 U. S.
551, 560 (2005)). “To enforce the Constitution’s protection
of human dignity,” we “loo[k] to the evolving standards of
decency that mark the progress of a maturing society,”
recognizing that “[t]he Eighth Amendment is not fastened
to the obsolete.” Hall, 572 U. S., at ___ (slip op., at 5)
(internal quotation marks omitted).
   In Atkins v. Virginia, we held that the Constitution
“restrict[s] . . . the State’s power to take the life of ” any
intellectually disabled individual. 536 U. S., at 321. See
also Hall, 572 U. S., at ___ (slip op., at 6); Roper, 543 U. S.,
at 563–564. Executing intellectually disabled individuals,
we concluded in Atkins, serves no penological purpose, see
536 U. S., at 318–320; runs up against a national consen-
sus against the practice, see id., at 313–317; and creates a
“risk that the death penalty will be imposed in spite of
factors which may call for a less severe penalty,” id., at
320 (internal quotation marks omitted); see id., at 320–
321.
   In Hall v. Florida, we held that a State cannot refuse to
entertain other evidence of intellectual disability when a
defendant has an IQ score above 70. 572 U. S., at ___–___
(slip op., at 21–22). Although Atkins and Hall left to the
States “the task of developing appropriate ways to enforce”
the restriction on executing the intellectually disabled, 572
U. S., at ___ (slip op., at 17) (quoting Atkins, 536 U. S., at
317), States’ discretion, we cautioned, is not “unfettered,”
572 U. S., at ___ (slip op., at 17). Even if “the views of
medical experts” do not “dictate” a court’s intellectual-
disability determination, id., at ___ (slip op., at 19), we
clarified, the determination must be “informed by the
medical community’s diagnostic framework,” id., at ___–
10                    MOORE v. TEXAS

                     Opinion of the Court

___ (slip op., at 19–20). We relied on the most recent (and
still current) versions of the leading diagnostic manuals—
the DSM–5 and AAIDD–11. Id., at ___, ___, ___–___, ___–
___ (slip op., at 3, 8, 10–11, 20–21). Florida, we concluded,
had violated the Eighth Amendment by “disregard[ing]
established medical practice.” Id., at ___ (slip op., at 10).
We further noted that Florida had parted ways with prac-
tices and trends in other States. Id., at ___–___ (slip op.,
at 12–16). Hall indicated that being informed by the
medical community does not demand adherence to every-
thing stated in the latest medical guide. But neither
does our precedent license disregard of current medical
standards.
                               III
   The CCA’s conclusion that Moore’s IQ scores established
that he is not intellectually disabled is irreconcilable with
Hall. Hall instructs that, where an IQ score is close to,
but above, 70, courts must account for the test’s “standard
error of measurement.” See id., at ___–___, ___–___ (slip
op., at 10–11, 21–22). See also Brumfield v. Cain, 576
U. S. ___, ___ (2015) (slip op., at 10) (relying on Hall to
find unreasonable a state court’s conclusion that a score of
75 precluded an intellectual-disability finding). As we
explained in Hall, the standard error of measurement is “a
statistical fact, a reflection of the inherent imprecision of
the test itself.” 572 U. S., at ___ (slip op., at 10). “For
purposes of most IQ tests,” this imprecision in the testing
instrument “means that an individual’s score is best un-
derstood as a range of scores on either side of the recorded
score . . . within which one may say an individual’s true IQ
score lies.” Id., at ___ (slip op., at 11). A test’s standard
error of measurement “reflects the reality that an individ-
ual’s intellectual functioning cannot be reduced to a single
numerical score.” Ibid. See also id., at ___–___ (slip op.,
at 10–12); DSM–5, at 37; AAIDD, User’s Guide: Intellec-
                     Cite as: 581 U. S. ____ (2017)                    11

                          Opinion of the Court

tual Disability: Definition, Classification, and Systems of
Supports 22–23 (11th ed. 2012) (hereinafter AAIDD–11
User’s Guide).
  Moore’s score of 74, adjusted for the standard error of
measurement, yields a range of 69 to 79, see 470 S. W. 3d,
at 519, as the State’s retained expert acknowledged, see
Brief for Petitioner 39, n. 18; App. 185, 189–190. Because
the lower end of Moore’s score range falls at or below 70,
the CCA had to move on to consider Moore’s adaptive
functioning. See Hall, 572 U. S., at ___–___ (slip op., at
21–22); 470 S. W. 3d, at 536 (Alcala, J., dissenting) (even if
the majority correctly limited the scores it would consider,
“current medical standards . . . would still require [the
CCA] to examine whether [Moore] has adaptive deficits”).
  Both Texas and the dissent maintain that the CCA
properly considered factors unique to Moore in disregard-
ing the lower end of the standard-error range. Post, at 14–
15; Brief for Respondent 41–42; see supra, at 6–7; 470
S. W. 3d, at 519. But the presence of other sources of
imprecision in administering the test to a particular indi-
vidual, see post, at 14–16, and n. 3, cannot narrow the
test-specific standard-error range.7
  In requiring the CCA to move on to consider Moore’s
adaptive functioning in light of his IQ evidence, we do not
suggest that “the Eighth Amendment turns on the slight-
est numerical difference in IQ score,” post, at 15–16. Hall
——————
  7 The  dissent suggests that Hall tacitly approved Idaho’s approach to
capital sentencing, which the dissent characterizes as “grant[ing] trial
courts discretion to draw ‘reasonable inferences’ about IQ scores and,
where appropriate, decline to consider the full range of the [standard
error of measurement].” Post, at 14–15 (quoting Hall, 572 U. S., at ___
(slip op., at 15) (quoting Pizzuto v. State, 146 Idaho 720, 729, 202 P. 3d
642, 651 (2008))). We referred in Hall to Idaho’s capital-sentencing
scheme, however, only to note that the State had “passed legislation
allowing a defendant to present additional evidence of intellectual
disability even when an IQ test score is above 70.” 572 U. S., at ___
(slip op., at 15).
12                    MOORE v. TEXAS

                     Opinion of the Court

invalidated Florida’s strict IQ cutoff because the cutoff
took “an IQ score as final and conclusive evidence of a
defendant’s intellectual capacity, when experts in the field
would consider other evidence.” 572 U. S., at ___ (slip op.,
at 10). Here, by contrast, we do not end the intellectual-
disability inquiry, one way or the other, based on Moore’s
IQ score. Rather, in line with Hall, we require that courts
continue the inquiry and consider other evidence of intel-
lectual disability where an individual’s IQ score, adjusted
for the test’s standard error, falls within the clinically
established range for intellectual-functioning deficits.
                             IV
  The CCA’s consideration of Moore’s adaptive functioning
also deviated from prevailing clinical standards and from
the older clinical standards the court claimed to apply.
                              A
   In concluding that Moore did not suffer significant
adaptive deficits, the CCA overemphasized Moore’s per-
ceived adaptive strengths. The CCA recited the strengths
it perceived, among them, Moore lived on the streets,
mowed lawns, and played pool for money. See 470 S. W.
3d, at 522–523, 526–527. Moore’s adaptive strengths, in
the CCA’s view, constituted evidence adequate to over-
come the considerable objective evidence of Moore’s adap-
tive deficits, see supra, at 4; App. to Pet. for Cert. 180a–
202a. See 470 S. W. 3d, at 522–524, 526–527. But the
medical community focuses the adaptive-functioning
inquiry on adaptive deficits. E.g., AAIDD–11, at 47 (“sig-
nificant limitations in conceptual, social, or practical
adaptive skills [are] not outweighed by the potential
strengths in some adaptive skills”); DSM–5, at 33, 38
(inquiry should focus on “[d]eficits in adaptive function-
ing”; deficits in only one of the three adaptive-skills do-
mains suffice to show adaptive deficits); see Brumfield,
                     Cite as: 581 U. S. ____ (2017)                    13

                          Opinion of the Court

576 U. S., at ___ (slip op., at 15) (“[I]ntellectually disabled
persons may have ‘strengths in social or physical capabili-
ties, strengths in some adaptive skill areas, or strengths in
one aspect of an adaptive skill in which they otherwise
show an overall limitation.’ ” (quoting AAMR, Mental
Retardation: Definition, Classification, and Systems of
Supports 8 (10th ed. 2002)).8
   In addition, the CCA stressed Moore’s improved behavior
in prison. 470 S. W. 3d, at 522–524, 526–527. Clinicians,
however, caution against reliance on adaptive strengths
developed “in a controlled setting,” as a prison surely is.
DSM–5, at 38 (“Adaptive functioning may be difficult to
assess in a controlled setting (e.g., prisons, detention cen-
ters); if possible, corroborative information reflecting func-
tioning outside those settings should be obtained.”); see
AAIDD–11 User’s Guide 20 (counseling against reliance on
“behavior in jail or prison”).
                              B
  The CCA furthermore concluded that Moore’s record of
academic failure, along with the childhood abuse and
suffering he endured, detracted from a determination that
his intellectual and adaptive deficits were related. See
470 S. W. 3d, at 488, 526; supra, at 5, 7–8. Those trau-
matic experiences, however, count in the medical commu-
nity as “risk factors” for intellectual disability. AAIDD–
11, at 59–60 (emphasis added). Clinicians rely on such
factors as cause to explore the prospect of intellectual
disability further, not to counter the case for a disability

——————
  8 The dissent suggests that disagreement exists about the precise role

of adaptive strengths in the adaptive-functioning inquiry. See post, at
11–12. But even if clinicians would consider adaptive strengths along-
side adaptive weaknesses within the same adaptive-skill domain,
neither Texas nor the dissent identifies any clinical authority permit-
ting the arbitrary offsetting of deficits against unconnected strengths in
which the CCA engaged, see 470 S. W. 3d, at 520–526.
14                     MOORE v. TEXAS

                      Opinion of the Court

determination. See id., at 60 (“[A]t least one or more of
the risk factors [described in the manual] will be found in
every case of ” intellectual disability.).
   The CCA also departed from clinical practice by requiring
Moore to show that his adaptive deficits were not related to
“a personality disorder.” 470 S. W. 3d, at 488; see id., at
526 (Moore’s problems in kindergarten were “more likely
cause[d]” by “emotional problems” than by intellectual
disability). As mental-health professionals recognize, how-
ever, many intellectually disabled people also have other
mental or physical impairments, for example, attention-
deficit/hyperactivity disorder, depressive and bipolar dis-
orders, and autism. DSM–5, at 40 (“[c]o-occurring men-
tal, neurodevelopmental, medical, and physical conditions
are frequent in intellectual disability, with rates of some
conditions (e.g., mental disorders, cerebral palsy, and epi-
lepsy) three to four times higher than in the general popu-
lation”); see AAIDD–11, at 58–63. Coexisting conditions
frequently encountered in intellectually disabled individ-
uals have been described in clinical literature as
“[c]omorbidit[ies].” DSM–5, at 40. See also Brief for
AAIDD et al. as Amici Curiae 20, and n. 25. The existence
of a personality disorder or mental-health issue, in short, is
“not evidence that a person does not also have intellectual
disability.” Brief for American Psychological Association,
APA, et al. as Amici Curiae 19.
                             C
  The CCA’s attachment to the seven Briseno evidentiary
factors further impeded its assessment of Moore’s adaptive
functioning.
                              1
  By design and in operation, the Briseno factors “creat[e]
an unacceptable risk that persons with intellectual dis-
ability will be executed,” Hall, 572 U. S., at ___ (slip op., at
                   Cite as: 581 U. S. ____ (2017)              15

                       Opinion of the Court

1). After observing that persons with “mild” intellectual
disability might be treated differently under clinical
standards than under Texas’ capital system, the CCA
defined its objective as identifying the “consensus of Texas
citizens” on who “should be exempted from the death
penalty.” Briseno, 135 S. W. 3d, at 6 (emphasis added).
Mild levels of intellectual disability, although they may
fall outside Texas citizens’ consensus, nevertheless remain
intellectual disabilities, see Hall, 572 U. S., at ___–___
(slip op., at 17–18); Atkins, 536 U. S., at 308, and n. 3;
AAIDD–11, at 153, and States may not execute anyone in
“the entire category of [intellectually disabled] offenders,”
Roper, 543 U. S., at 563–564 (emphasis added); see supra,
at 9.
   Skeptical of what it viewed as “exceedingly subjective”
medical and clinical standards, the CCA in Briseno ad-
vanced lay perceptions of intellectual disability. 135
S. W. 3d, at 8; see supra, at 5–6, and n. 6. Briseno asks,
for example, “Did those who knew the person best during
the developmental stage—his family, friends, teachers,
employers, authorities—think he was mentally retarded at
that time, and, if so, act in accordance with that determi-
nation?” 135 S. W. 3d, at 8. Addressing that question
here, the CCA referred to Moore’s education in “normal
classrooms during his school career,” his father’s reactions
to his academic challenges, and his sister’s perceptions of
Moore’s intellectual abilities. 470 S. W. 3d, at 526–527.
But the medical profession has endeavored to counter lay
stereotypes of the intellectually disabled. See AAIDD–11
User’s Guide 25–27; Brief for AAIDD et al. as Amici Cu-
riae 9–14, and nn. 11–15.         Those stereotypes, much
more than medical and clinical appraisals, should spark
skepticism.9
——————
  9 As elsewhere in its opinion, the CCA, in its deployment of the

Briseno factors, placed undue emphasis on adaptive strengths, see
16                         MOORE v. TEXAS

                          Opinion of the Court

                               2
   The Briseno factors are an outlier, in comparison both to
other States’ handling of intellectual-disability pleas and
to Texas’ own practices in other contexts. See Hall, 572
U. S., at ___ (slip op., at 12) (consensus in the States pro-
vides “objective indicia of society’s standards in the con-
text of the Eighth Amendment” (internal quotation marks
omitted)). No state legislature has approved the use of the
Briseno factors or anything similar. In the 12 years since
Texas adopted the factors, only one other state high court
and one state intermediate appellate court have author-
ized their use. See, e.g., Commonwealth v. Bracey, 632 Pa.
75, ___–___, 117 A. 3d 270, 286–287 (2015); Howell v.
State, 2011 WL 2420378, *18 (Tenn. Crim. App., June 14,
2011).
   Indeed, Texas itself does not follow Briseno in contexts
other than the death penalty. See Brief for Constitution
Project as Amicus Curiae 14–17. For example, the related-
ness requirement Texas defends here, see supra, at 5–6,
is conspicuously absent from the standards the State uses
to assess students for intellectual disabilities. See 19 Tex.
Admin. Code §89.1040(c)(5) (2015). And even within
Texas’ criminal-justice system, the State requires the
intellectual-disability diagnoses of juveniles to be based on
“the latest edition of the DSM.” 37 Tex. Admin. Code
§380.8751(e)(3) (2016). Texas cannot satisfactorily explain
why it applies current medical standards for diagnosing
intellectual disability in other contexts, yet clings to su-
perseded standards when an individual’s life is at stake.10
——————
supra, at 12–13; 470 S. W. 3d, at 527, and regarded risk factors for
intellectual disability as evidence of the absence of intellectual disabil-
ity, see supra, at 13–14; 470 S. W. 3d, at 526–527.
   10 Given the Briseno factors’ flaws, it is unsurprising that scholars

and experts have long criticized the factors. See, e.g., American Bar
Assn., Evaluating Fairness and Accuracy in State Death Penalty
Systems: The Texas Capital Punishment Assessment Report 395 (2013)
                     Cite as: 581 U. S. ____ (2017)                   17

                          Opinion of the Court 


                               V

  As noted supra, at 9, States have some flexibility, but
not “unfettered discretion,” in enforcing Atkins’ holding.
Hall, 572 U. S., at ___ (slip op., at 17). “If the States were
to have complete autonomy to define intellectual disability
as they wished,” we have observed, “Atkins could become a
nullity, and the Eighth Amendment’s protection of human
dignity would not become a reality.” Id., at ___–___ (slip
op., at 18–19).
  The medical community’s current standards supply one
constraint on States’ leeway in this area. Reflecting im-
proved understanding over time, see DSM–5, at 7;
AAIDD–11, at xiv–xv, current manuals offer “the best
available description of how mental disorders are ex-
pressed and can be recognized by trained clinicians,”
DSM–5, at xli. See also Hall, 572 U. S., at ___, ___, ___,
___–___, ___–___ (slip op., at 2, 3, 8, 10–11, 20–21) (em-
ploying current clinical standards); Atkins, 536 U. S., at
308, n. 3, 317, n. 22 (relying on then-current standards).
  In Moore’s case, the habeas court applied current medi-
cal standards in concluding that Moore is intellectually
disabled and therefore ineligible for the death penalty.
See, e.g., App. to Pet. for Cert. 150a–151a, 200a–203a.
——————
(“The Briseno factors create an especially high risk that [an intellectu-
ally disabled defendant] will be executed because, in many ways, they
contradict established methods for diagnosing [intellectual disabil-
ity].”); Blume, Johnson, & Seeds, Of Atkins and Men: Deviations from
Clinical Definitions of Mental Retardation in Death Penalty Cases
(footnote omitted), 18 Cornell J. L. & Pub. Pol’y 689, 710–712 (2009)
(“The Briseno factors present an array of divergences from the clinical
definitions.”); Macvaugh & Cunningham, Atkins v. Virginia: Implica-
tions and Recommendations for Forensic Practice, 37 J. Psychiatry & L.
131, 136 (2009) (“The seven criteria of the Briseno opinion operational-
ize an Atkins interpretation that [exempts only] a subcategory of
persons with [intellectual disabilities] from execution.”). See also 470
S. W. 3d, at 529–530, and n. 5 (Alcala, J., dissenting) (summarizing, in
this case, scholarly criticism of Briseno).
18                    MOORE v. TEXAS

                     Opinion of the Court

The CCA, however, faulted the habeas court for “disre-
garding [the CCA’s] case law and employing the definition
of intellectual disability presently used by the AAIDD.”
470 S. W. 3d, at 486. The CCA instead fastened its
intellectual-disability determination to “the AAMR’s 1992
definition of intellectual disability that [it] adopted in
Briseno for Atkins claims presented in Texas death-
penalty cases.” Ibid. By rejecting the habeas court’s
application of medical guidance and clinging to the stand-
ard it laid out in Briseno, including the wholly nonclinical
Briseno factors, the CCA failed adequately to inform itself
of the “medical community’s diagnostic framework,” Hall,
572 U. S., at ___–___ (slip op., at 19–20). Because Briseno
pervasively infected the CCA’s analysis, the decision of
that court cannot stand.
                        *     *    *
  For the reasons stated, the judgment of the Texas Court
of Criminal Appeals is vacated, and the case is remanded
for further proceedings not inconsistent with this opinion.

                                            It is so ordered.
                 Cite as: 581 U. S. ____ (2017)           1

                   ROBERTS, C. J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                          No. 15–797
                         _________________


   BOBBY JAMES MOORE, PETITIONER v. TEXAS
         ON WRIT OF CERTIORARI TO THE COURT OF

              CRIMINAL APPEALS OF TEXAS

                       [March 28, 2017]


   CHIEF JUSTICE ROBERTS, with whom JUSTICE THOMAS
and JUSTICE ALITO join, dissenting.
   The Texas Court of Criminal Appeals (CCA) concluded
that Bobby James Moore was not intellectually disabled so
as to be exempt from the death penalty under Atkins v.
Virginia, 536 U. S. 304 (2002). It reached that conclusion
based on its findings that he had failed to establish either
significantly subaverage intellectual functioning or related
significant deficits in adaptive behavior. The latter con-
clusion was based, in part, on the CCA’s analysis of a set
of seven “evidentiary factors” from Ex parte Briseno, 135
S. W. 3d 1, 8 (Tex. Crim. App. 2004). I agree with the
Court today that those factors are an unacceptable method
of enforcing the guarantee of Atkins, and that the CCA
therefore erred in using them to analyze adaptive deficits.
But I do not agree that the CCA erred as to Moore’s intel-
lectual functioning. Because the CCA’s determination on
that ground is an independent basis for its judgment, I
would affirm the decision below.
   My broader concern with today’s opinion, however, is
that it abandons the usual mode of analysis this Court has
employed in Eighth Amendment cases. The Court over-
turns the CCA’s conclusion that Moore failed to present
sufficient evidence of both inadequate intellectual func-
tioning and significant deficits in adaptive behavior with-
out even considering “objective indicia of society’s stand-
2                     MOORE v. TEXAS

                   ROBERTS, C. J., dissenting

ards” reflected in the practices among the States. Hall v.
Florida, 572 U. S. ___, ___ (2014) (slip op., at 12) (quoting
Roper v. Simmons, 543 U. S. 551, 563 (2005)). The Court
instead crafts a constitutional holding based solely on
what it deems to be medical consensus about intellectual
disability. But clinicians, not judges, should determine
clinical standards; and judges, not clinicians, should de-
termine the content of the Eighth Amendment. Today’s
opinion confuses those roles, and I respectfully dissent.
                             I
   On April 25, 1980, Moore and two others were throwing
dice when they decided to commit a robbery to obtain
money for car payments. Moore provided the group with
two firearms, and the three men began to drive around
Houston looking for a target. Eventually they settled on
the Birdsall Super Market. After negotiating their respec-
tive shares of the money they intended to steal and don-
ning disguises, the three went inside, heading straight to a
courtesy booth staffed by James McCarble and Edna Scott.
When Scott realized a robbery was occurring and
screamed, Moore shot McCarble in the head, killing the
70-year-old instantly.
   Moore fled Houston and remained on the run until his
arrest in Louisiana ten days after the murder. After
giving a written statement admitting his participation in
the robbery and killing, Moore was charged with capital
murder. A jury convicted him and sentenced him to death.
   Over the next three decades, Moore’s case traversed the
state and federal court systems, finally reaching the At-
kins hearing at issue today in 2014. The state habeas
court conducted a two-day evidentiary hearing, during
which it heard testimony from family members, a fellow
inmate, a prison official, and four mental health profes-
sionals. The court concluded that Moore had shown intel-
lectual disability and recommended that he be granted
                 Cite as: 581 U. S. ____ (2017)            3

                   ROBERTS, C. J., dissenting

relief.
   But it was just that: a recommendation. Under Texas
law, the CCA, not the habeas court, is the ultimate fact-
finder in habeas corpus proceedings. Ex parte Reed, 271
S. W. 3d 698, 727 (Tex. Crim. App. 2008); see also Ex parte
Moore, 470 S. W. 3d 481, 489 (Tex. Crim. App. 2015).
Assuming that role, the CCA declined to adopt the habeas
court’s findings and conclusions, instead conducting its
own review of the record to determine whether Moore had
shown he was intellectually disabled.
   The CCA began by considering the appropriate legal
standard for assessing intellectual disability. Following
our instruction to the States to “develop[ ] appropriate
ways to enforce” Atkins, 536 U. S., at 317 (internal quota-
tion marks omitted), the CCA had set out a legal definition
for intellectual disability in its prior decision in Ex parte
Briseno. Rather than follow that test, the habeas court
below crafted its own standards for intellectual disability.
But “[t]he decision to modify the legal standard for intel-
lectual disability in the capital-sentencing context,” the
CCA explained, “rests with this Court unless and until the
Legislature acts.” 470 S. W. 3d, at 487. Just as we have
corrected lower courts for taking it upon themselves to
dismiss our precedent as outdated, see, e.g., Bosse v. Okla-
homa, 580 U. S. ___, ___ (2016) (per curiam) (slip op., at
2), so too the CCA rebuked the habeas court for ignoring
binding CCA precedent.
   The CCA went on to explain why there was no reason to
modify the legal standard it had previously set out.
Briseno had stated a rule that in order for an Atkins
claimant to demonstrate intellectual disability he must
show (1) significantly subaverage general intellectual
functioning and (2) related limitations in adaptive func-
tioning, (3) which had appeared prior to age 18. See 470
S. W. 3d, at 486. It also laid out a set of seven evidentiary
factors—the “Briseno factors”—designed to assist “fact-
4                      MOORE v. TEXAS

                    ROBERTS, C. J., dissenting

finders . . . in weighing evidence” of intellectual disability.
Briseno, 135 S. W. 3d, at 8.
   The three-prong definition of intellectual disability came
directly from the ninth edition of the manual published by
what is now the American Association on Intellectual and
Developmental Disabilities (AAIDD). Id., at 7; see Ameri-
can Association on Mental Retardation, Mental Retarda-
tion: Definition, Classification, and Systems of Supports 5
(9th ed. 1992). By the time Moore’s case reached the CCA,
the AAIDD no longer included the requirement that adap-
tive deficits be “related” to intellectual functioning. But,
as the CCA noted, the most recent version of the other
leading diagnostic manual, the DSM–5, did include that
requirement. 470 S. W. 3d, at 487, n. 5; American Psychi-
atric Association, Diagnostic and Statistical Manual of
Mental Disorders 38 (5th ed. 2013) (hereinafter DSM–5).
So the CCA was faced with a choice in Moore: Keeping the
relatedness requirement would be inconsistent with the
AAIDD’s current guidance; dropping it would be out of
step with the newest version of the DSM. The CCA con-
cluded that “the legal test we established in Briseno re-
mains adequately ‘informed by the medical community’s
diagnostic framework,’ ” and went on to evaluate the case
under that approach. 470 S. W. 3d, at 487 (quoting Hall,
572 U. S., at ___–___ (slip op., at 19–20)).
   Starting with intellectual functioning, the CCA conducted
a painstaking analysis of the battery of tests Moore had
taken over the past 40 years. The CCA concluded that five
of the tests the habeas court had considered were unreli-
able: two of them were neuropsychological tests rather than
formal IQ measures; two were group-administered tests,
which Moore’s own experts had criticized, App. 12 (Otis-
Lennon Mental Abilities Test “not accepted as an instru-
ment appropriate for the assessment of mental retardation
or intellectual deficiency”); id., at 115–116 (Slosson is “not
the greatest test” and “not the most reliable approach”);
                 Cite as: 581 U. S. ____ (2017)            5

                   ROBERTS, C. J., dissenting

and the administrator of the fifth test concluded it was
“not . . . a valid score” because of evidence of suboptimal
effort, id., at 203.
   That left two scores for the CCA to analyze: a 78 and a
74. Significantly subaverage intellectual functioning is
“generally shown by an [IQ] of 70 or less.” 470 S. W. 3d, at
486. “Taking into account the standard error of measure-
ment” for the 78 score yielded a range of 73 to 83—i.e., a
range that did not include an IQ of 70 or less. Id., at 519.
As for the 74, the CCA again considered the standard
error of measurement, which yielded a score range of 69 to
79. The lower end of that range placed Moore within the
parameters for significantly subaverage intellectual func-
tioning. The CCA found, however, that Moore’s score was
unlikely to be in the lower end of the error-generated
range because he was likely exerting poor effort and expe-
riencing depression at the time the test was adminis-
tered—both factors that Moore’s experts agreed could
artificially deflate IQ scores. Id., at 516–517, 519; App.
46, 92. The CCA accordingly concluded that Moore had
failed to present sufficient evidence of significantly subav-
erage intellectual functioning.
   Having failed one part of the CCA’s three-part test,
Moore could not be found intellectually disabled. The CCA
nonetheless went on to consider the second prong of the
test, Moore’s adaptive deficits. Moore had taken a stand-
ardized test of adaptive functioning in which he scored
more than two standard deviations below the mean. But
Dr. Kristi Compton, the state expert who had adminis-
tered that test, explained that it was not an accurate
measure of Moore’s abilities. She reached this conclusion
not because of Moore’s adaptive strengths but instead
because “she had to assign zeroes to questions asking
about areas to which [Moore] had no exposure, such as
writing a check and using a microwave oven.” 470
S. W. 3d, at 522. Dr. Compton further opined that her
6                     MOORE v. TEXAS

                   ROBERTS, C. J., dissenting

evaluation of Moore and review of documentary evi-
dence—including school, trial, and prison records—did not
show adaptive deficits sufficient for an intellectual disabil-
ity diagnosis. App. 185; see 470 S. W. 3d, at 521–524.
   The CCA also considered and recounted the testimony of
the other experts who, unlike Dr. Compton, concluded that
Moore had shown significant adaptive deficits. As fact-
finders often do in confronting conflicting evidence, the
CCA made a credibility determination. The opinion of Dr.
Compton, the CCA concluded, was “far more credible and
reliable” than those of Moore’s experts, given Dr. Comp-
ton’s “considerable experience,” “thorough[ ] and rigorous[ ]
review[ ] [of] a great deal of material,” and personal evalu-
ation of Moore. Id., at 524. Based on Dr. Compton’s ex-
pert opinion, the CCA concluded Moore had failed to
demonstrate significant adaptive deficits.
   Finally, the CCA considered whether, even assuming
that Moore had made sufficient showings as to intellectual
functioning and adaptive deficits, those two were related.
Again finding Dr. Compton’s testimony the most credible,
the CCA concluded that “the record overwhelmingly sup-
ports the conclusion” that Moore’s observed academic and
social difficulties stemmed, not from low intellectual abili-
ties, but instead from outside factors like the trauma
and abuse he suffered as a child and his drug use at a
young age. Id., at 526. The CCA explained that, in addi-
tion to Dr. Compton’s expert testimony, consideration
of the seven Briseno factors reinforced that relatedness
conclusion.
   Given that Moore had failed to present sufficient evi-
dence on intellectual functioning or related adaptive defi-
cits, the CCA “conclude[d] that for Eighth Amendment
purposes,” Moore had not shown he was intellectually
disabled. 470 S. W. 3d, at 527. Accordingly, he was not
exempt from execution under Atkins.
                 Cite as: 581 U. S. ____ (2017)            7

                   ROBERTS, C. J., dissenting

                              II

                               A

    This Court’s precedents have emphasized the im-
portance of state legislative judgments in giving content to
the Eighth Amendment ban on cruel and unusual pun-
ishment. “Eighth Amendment judgments should not be
. . . merely the subjective views of individual Justices.”
Coker v. Georgia, 433 U. S. 584, 592 (1977) (plurality
opinion). For that reason, we have emphasized that
“judgment should be informed by objective factors to the
maximum possible extent.” Ibid. The “clearest and most
reliable objective evidence of contemporary values” comes
from state legislative judgments. Atkins, 536 U. S., at 312
(internal quotation marks omitted).         Such legislative
judgments are critical because in “a democratic society
legislatures, not courts, are constituted to respond to the
will and consequently the moral values of the people.”
Gregg v. Georgia, 428 U. S. 153, 175 (1976) (joint opinion
of Stewart, Powell, and Stevens, JJ.) (internal quotation
marks omitted). And we have focused on state enactments
in this realm because of the “deference we owe to the
decisions of the state legislatures under our federal sys-
tem . . . where the specification of punishments is con-
cerned.” Id., at 176. For these reasons, we have described
state legislative judgments as providing “essential instruc-
tion” in conducting the Eighth Amendment inquiry. Roper,
543 U. S., at 564.
    Our decisions addressing capital punishment for the
intellectually disabled recognize the central significance of
state consensus. In holding that the Eighth Amendment
prohibits the execution of intellectually disabled individu-
als in Atkins, the Court first identified a national consen-
sus against the practice and then, applying our own “inde-
pendent evaluation of the issue,” concluded that there was
“no reason to disagree” with that consensus. 536 U. S., at
321. The scope of our holding—guided as it was by the
8                     MOORE v. TEXAS

                   ROBERTS, C. J., dissenting

national consensus—swept only as far as that consensus.
We recognized that there remained the potential for “seri-
ous disagreement . . . in determining which offenders are
in fact retarded.” Id., at 317. And we did not seek to
provide “definitive procedural or substantive guides for
determining when a person who claims mental retardation
will be so impaired as to fall within Atkins’ compass.”
Bobby v. Bies, 556 U. S. 825, 831 (2009) (alterations and
internal quotation marks omitted). Instead, we left “to the
States the task of developing appropriate ways to enforce
the constitutional restriction upon their execution of
sentences.” Atkins, 536 U. S., at 317 (quoting Ford v.
Wainwright, 477 U. S. 399, 416–417 (1986); alterations
omitted).
   Twelve years after Atkins, the Court confronted one
State’s attempt to enforce the holding of that case. Hall v.
Florida considered Florida’s rule requiring a prisoner to
present an IQ score of 70 or below to make out an Atkins
claim. Although the Court thought it “proper to consider
the psychiatric and professional studies that elaborate on
the purpose and meaning of IQ scores,” it emphasized that
“[t]he legal determination of intellectual disability is
distinct from a medical diagnosis.” 572 U. S., at ___, ___
(slip op., at 7, 19). It was “the Court’s duty”—not that of
medical experts—“to interpret the Constitution.” Id., at
___ (slip op., at 19). The Court’s conclusion that Florida’s
rule was “in direct opposition to the views of those who
design, administer, and interpret the IQ test” was not
enough to decide the case. Id., at ___ (slip op., at 22).
Instead, consistent with our settled approach, the Court
canvassed “the legislative policies of various States,” as
well as “the holdings of state courts,” because it was state
policies that provided “essential instruction” for determin-
ing the scope of the constitutional guarantee. Id., at ___,
___ (slip op., at 7, 19) (quoting Roper, 543 U. S., at 564).
State policy, the Court concluded, indicated a “consensus
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                   ROBERTS, C. J., dissenting

that our society does not regard [Florida’s rule] as proper
or humane,” and that “consensus . . . instruct[ed us] how
to decide the specific issue presented.” 572 U. S., at ___,
___ (slip op., at 7, 16). The Court was sharply divided on
that conclusion, see id., at ___–___ (slip op., at 4–7)
(ALITO, J., dissenting), but not on the fact that our prece-
dent mandated such an inquiry.
                              B
   Today’s decision departs from this Court’s precedents,
followed in Atkins and Hall, establishing that the deter-
mination of what is cruel and unusual rests on a judicial
judgment about societal standards of decency, not a medi-
cal assessment of clinical practice. The Court rejects the
CCA’s conclusion that Moore failed to make the requisite
showings with respect to intellectual functioning and
adaptive deficits, without any consideration of the state
practices that were, three Terms ago, “essential” to the
Eighth Amendment question. Hall, 572 U. S., at ___ (slip
op., at 19). The Court instead finds error in the CCA’s
analysis based solely on what the Court views to be depar-
ture from typical clinical practice.
   The clinical guides on which the Court relies today are
“designed to assist clinicians in conducting clinical as-
sessment, case formulation, and treatment planning.”
DSM–5, at 25. They do not seek to dictate or describe who
is morally culpable—indeed, the DSM–5 cautions its
readers about “the imperfect fit between the questions of
ultimate concern to the law and the information con-
tained” within its pages. Ibid.
   The Eighth Amendment, under our precedent, is sup-
posed to impose a moral backstop on punishment, prohib-
iting sentences that our society deems repugnant. The
Court, however, interprets that constitutional guarantee
as turning on clinical guidelines that do not purport to
reflect standards of decency. The Court’s refusal even to
10                    MOORE v. TEXAS

                   ROBERTS, C. J., dissenting

address what we previously “pinpointed” as “the clearest
and most reliable objective evidence” of such standards—
the practices among the States—goes unexplained by the
majority. Atkins, 536 U. S., at 312 (internal quotation
marks omitted).
   A second problem with the Court’s approach is the lack
of guidance it offers to States seeking to enforce the hold-
ing of Atkins. Recognizing that we have, in the very re-
cent past, held that “ ‘the views of medical experts’ do not
‘dictate’ a court’s intellectual-disability determination,”
the Court assures us that it is not requiring adherence “to
everything stated in the latest medical guide,” ante, at 9–
10 (quoting Hall, 572 U. S., at ___ (slip op., at 19)); States
have “some flexibility” but cannot “disregard” medical
standards. Ante, at 10, 17. Neither the Court’s articula-
tion of this standard nor its application sheds any light on
what it means.
   Start with the Court’s stated principle. “Disregard”
normally means to dismiss as unworthy of attention, and
that is plainly not what the CCA did here. For example,
the Court faults the CCA for placing too much weight on
Moore’s adaptive strengths and functioning in prison,
implying that this marked a dismissal of clinical stand-
ards. Yet the CCA was aware of and, in a prior decision,
had addressed the fact that some clinicians would counsel
against considering such information. See 470 S. W. 3d, at
489 (citing Ex parte Cathey, 451 S. W. 3d 1, 26–27 (2014)).
Both because “[m]ost courts . . . consider all of the person’s
functional abilities” and because it seemed “foolhardy” to
ignore strengths, the CCA thought it proper to take note of
them. Id., at 27. As to prison conduct, the CCA decided
that the fundamental questions the Atkins inquiry sought
to answer were best considered—and “sound scientific
principles” best served—by taking account of “all possible
data that sheds light on a person’s adaptive functioning,
including his conduct in a prison society.” 451 S. W. 3d, at
                  Cite as: 581 U. S. ____ (2017)           11

                   ROBERTS, C. J., dissenting

26–27. The CCA considered clinical standards and ex-
plained why it decided that departure from those stand-
ards was warranted. The court did not “disregard” medi-
cal standards.
   Nor do the Court’s identified errors clarify the scope of
the “flexibility” we are told States retain in this area. The
Court faults the CCA for “overemphasiz[ing]” strengths
and “stress[ing]” Moore’s conduct in prison, ante, at 12–13,
suggesting that some—but not too much—consideration of
strengths and prison functioning is acceptable. The
Court’s only guidance on when “some” becomes “too
much”? Citations to clinical guides. See ibid. But if
courts do have “flexibility” in enforcing the guarantee of
Atkins and need not “adhere[ ]” to these guides in every
instance or particular, ante, at 10, 17, then clinical texts,
standing alone, cannot answer the question of why the
CCA placed too much weight on adaptive strengths and
prison conduct.      The line between the permissible—
consideration, maybe even emphasis—and the forbidden—
“overemphasis”—is not only thin, but totally undefined by
today’s decision. It is not at all clear when a State’s devia-
tion from medical consensus becomes so great as to “di-
minish the force” of that consensus, ante, at 2, and thereby
violate the Constitution.
   Finally, the Court’s decision constitutionalizes rules for
which there is not even clinical consensus—a consequence
that will often arise from the approach charted by the
Court today. Consider the Court’s conclusion that, contrary
to “the medical community[’s] focus[] . . . on adaptive
deficits,” “the CCA overemphasized Moore’s perceived
adaptive strengths.” Ante, at 12. In support of this propo-
sition, the Court cites the AAIDD’s direction that “signifi-
cant limitations in conceptual, social, or practical adaptive
skills [are] not outweighed by the potential strengths in
some adaptive skills.” AAIDD, Intellectual Disability:
Definition, Classification, and Systems of Supports 47
12                      MOORE v. TEXAS

                     ROBERTS, C. J., dissenting

(11th ed. 2010) (hereinafter AAIDD–11). Even assuming
that all clinicians would agree with this statement, there
are a number of ways it might be interpreted: as meaning
that strengths in one of the three adaptive skill areas—
conceptual, social, and practical—should not cancel out
deficits in another; as meaning that strengths should not
outweigh deficits within the same skill area; or as mean-
ing that evidence of some ability to perform a skill should
not offset evidence of the inability to perform that same
skill. And it appears that clinicians do, in fact, disagree
about what this direction means. Compare, e.g., Brief for
AAIDD et al. as Amici Curiae 17 (“The clinician’s diagnos-
tic focus does not—and cannot—involve any form of ‘bal-
ancing’ deficits against the abilities or strengths which the
particular individual may also possess” (emphasis added))
with Hagan, Drogin, & Guilmette, Assessing Adaptive
Functioning in Death Penalty Cases after Hall and DSM–
5, 44 J. Am. Acad. Psychiatry & L. 96, 98 (2016) (“Any
assessment of adaptive functioning must give sufficient
consideration to assets and deficits alike. . . . [I]n-
ventorying only assets or deficits . . . departs from DSM–5,
[the AAIDD–11], and all other established frameworks”
(footnotes omitted)).
   The same is true about consideration of prison conduct.
The two primary clinical guides do offer caution about
considering functioning in prison. But the stringency of
their caution differs, with the AAIDD seeming to enact a
flat ban on ever looking to functioning in prison and the
DSM urging “if possible” to consider “corroborative infor-
mation reflecting functioning outside” of prison. AAIDD,
User’s Guide: Intellectual Disability: Definition, Classifi-
cation, and Systems of Supports 20 (11th ed. 2012); DSM–
5, at 38. The CCA followed the DSM–5’s instruction,
relying on Dr. Compton’s conclusion that “even before
[Moore] went to prison” he demonstrated a “level of adap-
tive functioning . . . too great . . . to support an intellectual-
                  Cite as: 581 U. S. ____ (2017)            13

                    ROBERTS, C. J., dissenting

disability diagnosis.” 470 S. W. 3d, at 526. In deter-
mining that the CCA erred in this regard, the Court im-
plicitly rejects the DSM–5’s approach to the proper consid-
eration of prison conduct and accepts what it takes to be
that of the AAIDD. The Court does not attempt to explain
its justification for why the Eighth Amendment should
favor one side over the other in this clinical debate.
   “Psychiatry is not . . . an exact science.” Ake v. Oklahoma,
470 U. S. 68, 81 (1985). “[B]ecause there often is no single,
accurate psychiatric conclusion,” we have emphasized the
importance of allowing the “primary factfinder[ ]” to “re-
solve differences in opinion . . . on the basis of the evidence
offered by each party.” Ibid. You would not know it from
reading the Court’s opinion today, but that is precisely
what the CCA—the factfinder under Texas law—did in the
decision below: Confronted with dueling expert opinions
about how to evaluate adaptive functioning and what
conclusion to reach, the CCA resolved the dispute before it
by accepting the testimony of the expert it deemed most
credible. Of course, reliance on an expert opinion does not
insulate a decision from further judicial review. But,
unlike the Court, I am unwilling to upset the considered
judgment of the forensic psychologist that the factfinding
court deemed the most credible based on my own interpre-
tation of a few sentences excised from medical texts.
                            III
  As for how I would resolve this case, there is one aspect
of the CCA’s approach to intellectual disability that is
incompatible with the Eighth Amendment: the Briseno
factors. As the Court explains, no state legislature has
approved the use of these or any similar factors. Although
the CCA reviewed these factors to determine whether
Moore’s adaptive deficits were “related” to his intellectual
functioning, it may be that consideration of those factors
tainted the whole of the CCA’s adaptive functioning anal-
14                         MOORE v. TEXAS

                        ROBERTS, C. J., dissenting

ysis. I need not decide this question, however, because the
CCA reached the issue of Moore’s adaptive functioning
only after concluding that he had failed to demonstrate
intellectual functioning sufficiently low to warrant a find-
ing of intellectual disability, regardless of his adaptive
deficits or their relation to his IQ. Moore has not presented
sufficient reason to upset that independent holding.
   The Court concludes that the CCA’s assessment of
Moore’s IQ scores is “irreconcilable with Hall.” Ante, at
10. Not so. Hall rejected a Florida rule that required a
prisoner to present an IQ score of 70 or below to demon-
strate intellectual disability, thereby barring consideration
of the standard error of measurement (SEM) of an over-70
score. But the CCA did not apply Florida’s rule—or any-
thing like it. The court in fact began by taking account of
the SEM, explaining that Moore’s tested score of 74 led to
an IQ range between 69 and 79. The court went on to
consider additional expert testimony about potential
factors affecting that score. Based on that evidence, the
CCA discounted portions of the SEM-generated range and
concluded that Moore’s IQ did not lie in the relevant range
for intellectual disability.
   Hall provided no definitive guidance on this sort of
approach: recognizing the inherent imprecision of IQ tests,
but considering additional evidence to determine whether
an SEM-generated range of scores accurately reflected a
prisoner’s actual IQ.1 Indeed, in its catalog of States that

——————
  1 Hall also reached no holding as to the evaluation of IQ when an

Atkins claimant presents multiple scores, noting only that “the analysis
of multiple IQ scores jointly is a complicated endeavor.” Hall v. Flor-
ida, 572 U. S. ___, ___ (2014) (slip op., at 11). The Court’s definition of
deficient intellectual functioning as shown by “an IQ score” of roughly
70, ante, at 4 (emphasis added), is dicta and cannot be read to call into
question the approach of States that would not treat a single IQ score
as dispositive evidence where the prisoner presented additional higher
scores.
                     Cite as: 581 U. S. ____ (2017)                    15

                       ROBERTS, C. J., dissenting

“ha[d] taken a position contrary to that of Florida,” the
Court in Hall included a State that granted trial courts
discretion to draw “reasonable inferences” about IQ scores
and, where appropriate, decline to consider the full range
of the SEM. 572 U. S., at ___, ___ (slip op., at 15, 16)
(quoting Pizzuto v. State, 146 Idaho 720, 729, 202 P. 3d
642, 651 (2008)).2 That is the approach the CCA took
here. If that approach was “contrary” to Florida’s rule in
Hall, I do not understand how Hall can be read to reject
that approach today.
   The Court’s ruling on intellectual functioning turns
solely on the fact that Moore’s IQ range was 69 to 79
rather than 70 to 80. See ante, at 11 (“Because the lower
end of Moore’s score range falls at or below 70, the CCA
had to move on to consider Moore’s adaptive functioning”).
The CCA certainly did not “disregard” SEM in assessing
Moore’s IQ, and it explained why other factors led it to
conclude that his actual score did not fall near the lower
end of the SEM range. Only by insisting on the absolute
conformity to medical standards the Court disclaims can it
find a violation of the Eighth Amendment based on that
one-point difference.3 Ibid. In concluding that the Eighth
——————
   2 The Court correctly notes that Hall cited Pizzuto as an instance of a

State that had enacted “legislation allowing a defendant to present
additional evidence of intellectual disability even when an IQ test score
is above 70.” Hall, 572 U. S., at ___ (slip op., at 15). The “additional
evidence” that Pizzuto considered, however, was evidence that would
indicate where within the SEM range a prisoner’s IQ likely fell, 146
Idaho, at 729, 202 P. 3d, at 651—that is, the same sort of evidence that
the CCA considered below.
   3 It is not obvious that clinicians would ignore evidence beyond the

SEM in determining the appropriate range that an IQ score represents.
See, e.g., Macvaugh & Cunningham, Atkins v. Virginia: Implications
and Recommendations for Forensic Practice, 37 J. Psychiatry & L. 131,
147 (2009) (“Error in intellectual assessment is not solely a function [of
the SEM]. Other sources of error or assessment imprecision may
involve the examinee . . . includ[ing] the mental and physical health,
mood, effort, and motivation of the examinee during testing . . . .”);
16                        MOORE v. TEXAS

                      ROBERTS, C. J., dissenting

Amendment turns on the slightest numerical difference in
IQ score, the Court today is just as wrong as the Florida
Supreme Court was in Hall.
   Today’s decision is not compelled by Hall; it is an expan-
sion of it. Perhaps there are reasons to expand Hall’s
holding—to say that States must read IQ tests as rigidly
encompassing the entire SEM range, regardless of any
other evidentiary considerations, or to say that the rea-
sons that the CCA gave for discounting the lower end of
Moore’s IQ range were improper. But before holding that
the Constitution demands either result, our precedent
requires consulting state judgments on the matter to
determine whether a national consensus has developed.
Moore has presented no argument as to such a consensus,
and the majority does not claim that there is one. Without
looking to any such “objective evidence of contemporary
values,” Atkins, 536 U. S., at 312 (internal quotation
marks omitted), there is a real danger that Eighth
Amendment judgments will embody “merely the subjective
views of individual Justices,” Coker, 433 U. S., at 592
(plurality opinion). As Justice Frankfurter cautioned,
“[o]ne must be on guard against finding in personal disap-
proval a reflection of more or less prevailing condemna-
tion.” Louisiana ex rel. Francis v. Resweber, 329 U. S. 459,
471 (1947) (concurring opinion).
   I respectfully dissent.




——————
AAIDD–11, at 100–101 (“When considering the relative weight or
degree of confidence given to any assessment instrument, the clinician
needs to consider . . . the conditions under which the test(s) was/were
given [and] the standard error of measurement”).
