Hamm v. Smith (2026)

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(Slip Opinion) Cite as: 608 U. S. ____ (2026) 1 Per Curiam NOTICE: This opinion is subject to formal revision before publication in the United States Reports. Readers are requested to notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, pio@supremecourt.gov, of any typographical or other formal errors. SUPREME COURT OF THE UNITED STATES _________________ No. 24–872 _________________ JOHN Q. HAMM, COMMISSIONER, ALABAMA DE- PARTMENT OF CORRECTIONS, PETITIONER v. JOSEPH CLIFTON SMITH ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE ELEVENTH CIRCUIT [May 21, 2026] PER CURIAM. The writ of certiorari is dismissed as improvidently granted. It is so ordered. Cite as: 608 U. S. ____ (2026) 1 SOTOMAYOR, J., concurring SUPREME COURT OF THE UNITED STATES _________________ No. 24–872 _________________ JOHN Q. HAMM, COMMISSIONER, ALABAMA DE- PARTMENT OF CORRECTIONS, PETITIONER v. JOSEPH CLIFTON SMITH ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE ELEVENTH CIRCUIT [May 21, 2026] JUSTICE SOTOMAYOR, with whom JUSTICE JACKSON joins, concurring. I concur in the Court’s decision to dismiss the writ of cer- tiorari as improvidently granted. I write separately for two reasons. First, based on the evidentiary record and how this litigation proceeded below, I explain why the Court should not and cannot use this case to address how courts must analyze multiple IQ scores under Atkins v. Virginia, 536 U. S. 304 (2002). Second, I point out how the principal dissent’s discussion of this Court’s precedents and the sci- entific consensus about how courts should evaluate multi- ple IQ scores is incomplete and potentially misleading. I A In 1998, Joseph Smith was convicted of first-degree mur- der. At his sentencing hearing, Smith introduced evidence of intellectual disability, including an IQ score of 72 and testimony from the test’s administrator explaining that the test’s standard error of measurement indicated Smith’s IQ could be as low as 69 or as high as 75.1 Smith also —————— 1 The standard error of measurement reflects the potential error inher- ent in an IQ test and is used to calculate a confidence interval, a “range 2 HAMM v. SMITH SOTOMAYOR, J., concurring introduced his school records, which showed that he was previously administered two IQ tests resulting in scores of 75 and 74 and that he was classified as “ ‘educable mentally retarded’ ” in 7th grade. Smith v. State, 71 So. 3d 12, 19–20 (Ala. Crim. App. 2008). At the time of Smith’s sentencing, this Court had held that it did not violate the Eighth Amendment to execute an intellectually disabled person so long as the sentencers considered mitigating evidence of the defendant’s intellectual disability among other aggravating or mitigating evidence. See Penry v. Lynaugh, 492 U. S. 302, 328, 330–335 (1989). The jury in Smith’s case returned an advisory verdict recommending the death penalty, which the trial judge imposed. The Alabama Supreme Court af- firmed Smith’s sentence. A few years later, this Court held in Atkins v. Virginia, 536 U. S. 304 (2002), that it violates the Eighth Amend- ment to execute an individual who is intellectually disabled. In so holding, the Court largely left it to the States to “ ‘de- velo[p] appropriate ways to enforce’ ” this limitation. Id., at 317. The Alabama Supreme Court responded by adopting a definition of intellectual disability that requires the de- fendant to prove three prongs, all by a preponderance of the evidence: (1) “significantly subaverage intellectual func- tioning (an IQ of 70 or below)”; (2) “significant or substan- tial deficits in adaptive behavior”; and (3) manifestation of “these problems . . . during the developmental period (i.e., before the defendant reached age 18).” Ex parte Perkins, 851 So. 2d 453, 456 (2002). After Atkins and Perkins were decided, Smith petitioned for postconviction relief in Alabama state court, alleging that he is intellectually disabled under Alabama’s defini- tion and that his execution would violate the Eighth Amendment. The trial court denied Smith’s request for an —————— within which one may say an individual’s true IQ score lies.” Hall v. Florida, 572 U. S. 701, 713 (2014). Cite as: 608 U. S. ____ (2026) 3 SOTOMAYOR, J., concurring evidentiary hearing and his petition, the Alabama Court of Criminal Appeals affirmed that decision, and the Alabama Supreme Court denied review. B Smith next petitioned for federal habeas relief in the Dis- trict Court for the Southern District of Alabama. The Dis- trict Court initially denied his petition, but the Eleventh Circuit reversed. The Court of Appeals held that the Dis- trict Court wrongly deferred to the Alabama Court of Crim- inal Appeals’ decision under 28 U. S. C. §2254(d) and re- manded for the District Court to conduct a de novo inquiry into whether Smith is intellectually disabled under Ala- bama’s definition of intellectual disability. Smith v. Camp- bell, 620 Fed. Appx. 734 (2015). Alabama did not file a pe- tition for a writ of certiorari to this Court. On remand in the District Court, Alabama and Smith agreed to an evidentiary hearing. See Smith v. Thomas, No. 1:05–cv–00474 (SD Ala., July 1, 2016), ECF Doc. 75. Both parties hired experts to administer new IQ tests: Dr. King for the State and Dr. Fabian for Smith. On the test administered by King, Smith scored a 74 with a 95% confi- dence interval of 70 to 79. On the test administered by Dr. Fabian, Smith scored a 78 with a 95% confidence interval of 72 to 83. At this point, Smith had obtained five IQ scores ranging from 72 to 78. The District Court then admitted expert reports from King, Fabian, and an additional expert proffered by Smith, and heard testimony from all three as to whether Smith is intellectually disabled. The experts each opined on Smith’s intellectual function- ing. The State’s expert, King, stated in his report that a score of 74 “would technically place [Smith in] the border- line range of intellectual functioning,” but that the score “is not reflective . . . of his true intellectual functioning,” which King described as “in the low average range of ability.” 2 App. 596. King explained that “a single . . . IQ score” is 4 HAMM v. SMITH SOTOMAYOR, J., concurring comprised of multiple subscores, which reflect different as- pects of one’s intellectual functioning, and a final score “needs to be additionally parsed in order to look at whether there is subtest scatter or whether there is consistency.” Id., at 596–597. In the IQ test that King administered, the scatter in Smith’s subscores was, in King’s view, more “in- dicative of . . . a learning disabilit[y]” than of intellectual disability. Id., at 598. King testified that, in his view, Smith did not have significantly subaverage intellectual functioning based “on all the data that [he] collected, all the records that [he] reviewed” and “all of the IQ tests that have been compiled over a lengthy period of time.” 1 id., at 271. He also explained that his conclusion was based in part on Smith’s “presentation to” and “ability to interact” with King. Id., at 271–272. Smith’s experts similarly reviewed all of Smith’s scores and records, but came to different conclusions. Fabian tes- tified that several of Smith’s prior scores were “in the range for intellectual disability,” id., at 244, and that, overall, Smith “meets the intellectual deficit prong of the intellec- tual disability definition,” id., at 179–180. Fabian ex- plained that even though Smith’s scores were above 70, one “need[s] to consider those IQ scores with the other areas of functioning,” such as his adaptive functioning, including ev- idence of his “academic achievement” and “executive func- tioning.” Id., at 180. Together, those latter considerations showed that, “cognitively[, Smith is] impaired in a number of areas” and that, according to Fabian, Smith’s IQ scores “in total can be considered consistent with significant limi- tations in intellectual disability.” Ibid. Smith’s second ex- pert, too, testified that Smith’s scores were “in the range of what would be considered mild intellectual disability,” “par- ticularly” when “consider[ing] the standard error of meas- urement.” Id., at 111; see also 3 id., at 875. In assessing Smith’s intellectual functioning, the District Court also considered a report by the expert who had Cite as: 608 U. S. ____ (2026) 5 SOTOMAYOR, J., concurring administered the 1998 test in which Smith scored a 72 with a standard error range of 69 to 75. That expert concluded that Smith’s score “places him at the 3rd percentile in com- parison to the general population,” and that Smith “‘oper- ates between the Low Average and Mentally Retarded range’ ” but “ ‘at a level closer to those individuals who would be considered mentally retarded.’ ” Smith v. Dunn, Civ. Action No. 05–00474 (SD Ala., Aug. 17, 2021), App. to Pet. for Cert. (Pet. App.) 73a. Based on all the evidence, the District Court found that whether Smith “qualifies as having significantly subaver- age intellectual function[ing]” was “not clear” and that this was a “close case.” Id., at 74a. The court acknowledged that King “testified that if there are multiple sources of IQ over a long period of time[,] it contributes to the construct of va- lidity indicating what a true IQ score is for an individual” and that “multiple IQ scores” in Smith’s case “place him in the borderline range, functioning just above intellectual disability.” Id., at 70a. However, the District Court did “not find [this evidence] strong enough to conclude that Smith is not intellectually disabled without considering evidence of his adaptive deficits” because Smith “did not consistently score so high that the [District] Court [wa]s confident that the lowest score can be thrown out as an outlier or that the standard error for the tests can be disregarded.” Ibid. The District Court observed that “at best Smith[’s] intelligence falls at the low end of the Borderline range of intelligence and at worst at the high end of the required significantly subaverage intellectual functioning.” Id., at 74a. It there- fore decided to consider “additional evidence,” including ev- idence about “whether Smith suffers from significant or substantial deficits in adaptive behavior,” to assess whether Smith is intellectually disabled. Ibid. From there, the District Court analyzed evidence of Smith’s adaptive deficits, which included Smith’s school records, testimony from Smith’s family members about 6 HAMM v. SMITH SOTOMAYOR, J., concurring Smith’s abilities, testimony from Smith himself, and the ex- pert opinions of King and Fabian. Id., at 75a–92a.2 The District Court also considered the results of other psycho- logical tests, which related to both the intellectual-function- ing and adaptive-functioning prongs. Id., at 90a–92a. After weighing all the evidence, the District Court found that “Smith has shown by a preponderance of the evidence that he has significantly subaverage intellectual function- ing and significant deficits in adaptive behavior.” Id., at 92a. The court also found that Smith’s intellectual- and adaptive-functioning issues “clearly arose before he was 18 years of age.” Id., at 96a. Based on these findings, the court concluded that Smith “is intellectually disabled and cannot constitutionally be executed.” Id., at 96a–97a. C The Eleventh Circuit initially affirmed, but this Court va- cated that decision because its basis was “unclear.” Hamm v. Smith, 604 U. S. 1, 2 (2024) (per curiam). The Court ex- plained that “the Eleventh Circuit’s opinion might be read to afford conclusive weight to the fact that the lower end of the standard-error range for Smith’s lowest IQ score is 69,” which “would suggest a per se rule that the lower end of the standard-error range for an offender’s lowest score is dis- positive” of the intellectual-functioning prong. Ibid. Alter- natively, the opinion could be read to “suggest a more holis- tic approach to multiple IQ scores that considers the relevant evidence, including as appropriate any relevant expert testimony.” Ibid. This Court noted that it “has not specified how courts should evaluate multiple IQ scores,” and asked the Eleventh Circuit to clarify its holding. Ibid. On remand, the Eleventh Circuit answered that it had used a “ ‘holistic approach.’ ” Smith v. Commissioner, Ala. —————— 2 The District Court “question[ed] the veracity” of some of King’s testi- mony because his criticism of Fabian’s methods was contradicted by his own prior testimony in other cases. See App. to Pet. for Cert. 89a. Cite as: 608 U. S. ____ (2026) 7 SOTOMAYOR, J., concurring Dept. of Corrections, No. 21–14519 (Nov. 14, 2024) (per cu- riam), Pet. App. 2a. It also “unambiguously reject[ed] any suggestion that a court may ever conclude that a capital de- fendant suffers from significantly subaverage intellectual functioning based solely on the fact that the lower end of the standard-error range for his lowest of multiple IQ scores is 69.” Ibid. It then affirmed the District Court’s decision, explaining that the District Court had properly considered “Smith’s IQ test results, taken together and in context of expert testimony,” and that its factual findings were not clearly erroneous. Id., at 5a. D Alabama filed a petition for a writ of certiorari proposing two questions: First, “[w]hether, under a proper application of Atkins, a State can require a claimant to prove an IQ of 70 or less by a preponderance of the evidence”; and second, “[w]hether courts evaluating multiple IQ scores must find that every valid score of ‘about’ 75 or less supports an At- kins claim.” Pet. for Cert. i. This Court declined to grant either question, and instead granted a question raised by the United States on the last two-and-a-half pages of its amicus brief: “Whether and how courts may consider the cumulative effect of multiple IQ scores in assessing an At- kins claim.” Brief for United States as Amicus Curiae on Pet. for Cert. I; see id., at 20–22. The United States did not identify any split among the lower courts on this issue. See id., at 20–22. II The Court is not equipped in this case to provide any meaningful guidance on how courts should assess multiple IQ scores. All the parties here agree that the Eighth Amendment does not prescribe a single formula for weigh- ing multiple IQ scores. All the parties also agree that At- kins gave States the primary role in “developing 8 HAMM v. SMITH SOTOMAYOR, J., concurring appropriate ways to enforce” Atkins. 536 U. S., at 317. Alt- hough the parties offer to this Court a variety of approaches to assessing multiple IQ scores that States could adopt, the litigation below did not focus on whether a precise method- ology exists that courts must use. Without the benefit of an evidentiary record or decisions below trained on the specific theories now advanced by the parties, this Court rightly concludes that it should not provide more detailed guidance beyond what this Court’s cases have previously said. A To start, and most significantly, the parties agree that there is no single approach to weighing multiple IQ scores. Alabama here disclaims any “single, mechanical rule . . . for aggregating multiple IQ scores.” Reply Brief 12 (internal quotation marks omitted; ellipsis in original). It instead of- fers a rule that a factfinding court must consider the “cu- mulative effect” of multiple IQ scores, by which it means that the scores must be “combine[d] to prove an IQ of 70 or below.” Id., at 1, 10. Alabama suggests that courts could do so using one of several methods, such as taking the me- dian, examining the “overlap among each score’s error range,” calculating a composite score, taking the average, or looking only at the highest score. Id., at 10–12, 19. Still, it acknowledges that there is no “consensus over whether and how to evaluate the cumulative effect of multiple IQ scores.” Brief for Petitioner 28. The United States agrees that “the Eighth Amendment” does not “prescrib[e] a specific approach to analyzing mul- tiple IQ tests.” Brief for United States as Amicus Curiae 19. It notes that it is “possible” to combine multiple scores into a composite score or into a “single range,” but contends only that “a court may take stock of the full range of . . . IQ scores,” not how a court must do so. Id., at 18–19. It also emphasizes that if a court considered multiple scores or a combination of those scores, such as a composite score, the Cite as: 608 U. S. ____ (2026) 9 SOTOMAYOR, J., concurring inquiry would “[o]f course . . . fall to the factfinder to assess and weigh this sort of expert analysis.” Id., at 19. Smith, for his part, contends that courts must assess mul- tiple IQ scores “holistically,” which includes “considering those scores in light of other evidence—particularly expert testimony—regarding the scores’ validity and meaning, and other evidence of the claimant’s intellectual functioning.” Brief for Respondent 2. Smith does not disagree with Ala- bama and the United States, however, that as part of that holistic analysis, courts could consider an aggregation of scores, such as a composite score, if one is presented. Thus, despite discussing different methods by which courts could assess multiple IQ scores, the parties all ap- pear to agree there is no particular method by which courts must consider multiple scores. B The Court’s review is further complicated by the fact that the issue of how to consider multiple IQ scores was neither meaningfully raised nor passed upon below. In the District Court, Alabama never argued that the court must, as a mat- ter of law, combine all IQ scores using any particular method (or set of methods) to assess whether an Atkins claimant has proven significantly subaverage intellectual functioning. See Respondent’s Post-Hearing Brief, ECF Doc. 129, pp. 36–46. Nor did Alabama argue that the Dis- trict Court must base its finding of intellectual functioning solely on Smith’s IQ scores, without considering evidence of Smith’s academic performance and adaptive functioning as well. See id., at 36 (arguing that Smith’s school records show he does not meet the intellectual-functioning prong, rather than asking the District Court to ignore those rec- ords). Instead, Alabama urged the District Court to apply Alabama’s state-law standard for assessing intellectual dis- ability, which it explained does not “preclude consideration of other evidence of intellectual disability, including 10 HAMM v. SMITH SOTOMAYOR, J., concurring testimony regarding adaptive deficits[,] when a person has an IQ over 70.” Id., at 4. In fact, none of the experts, not even the State’s expert, combined Smith’s scores using any method that Alabama now claims is necessary. Not one of the experts calculated a composite score, used the mean or median, examined the “overlap” of the scores’ error ranges, or relied solely on the highest score. Nor did any expert testify that using such methods was the most scientifically sound way to evaluate Smith’s intellectual functioning. Instead, all three consid- ered all the scores in addition to other evidence and used their own clinical judgment to render conclusions about Smith’s intellectual functioning. In other words, each ex- pert assessed the scores holistically. Nor did Alabama appeal the District Court’s determina- tion on this basis. In its brief to the Eleventh Circuit, Ala- bama argued that the District Court improperly shifted the burden of proof onto the State to prove that Smith was not intellectually disabled and that its factual determinations were clearly erroneous. At no point did Alabama contend that the District Court erred by failing to combine Smith’s scores using one of the methods it now claims is required. Unsurprisingly, then, neither the District Court nor the Eleventh Circuit specifically addressed whether a court must consider the “cumulative effect” of Smith’s IQ scores by combining them using a specific method, or whether one method is better than another, or even how a court should go about deciding which method is preferable. Instead, based on the arguments and evidence raised, the Eleventh Circuit held that the District Court did not err in its “‘ho- listic’ ” consideration of Smith’s scores and that its factual determination that Smith has significant subaverage intel- lectual functioning was not clearly erroneous “based on the complete record, including any relevant expert testimony.” Pet. App. 2a. Cite as: 608 U. S. ____ (2026) 11 SOTOMAYOR, J., concurring What is more, it does not appear that a single state legis- lature or court or Federal Court of Appeals has adopted Al- abama’s proposed rule that courts must combine multiple IQ scores using any one method (or a set of methods); nor has any adopted a rule prohibiting courts from assessing multiple scores holistically without combining them, just as the District Court did here. This Court is therefore right to exercise caution and decline to adopt any such rules now.3 C The principal dissent claims that the Court should have taken this opportunity to provide “much-needed guidance” to lower courts. Post, at 1 (opinion of ALITO, J.). At the outset, there is no evidence that the lower courts are des- perate for guidance; there is no split and neither state courts nor federal courts have expressed substantial confu- sion over how to assess multiple IQ scores. See, e.g., Black v. Carpenter, 866 F. 3d 734, 743–749 (CA6 2017) (affirming the District Court’s review of 10 scores and expert testi- mony interpreting those scores); Jackson v. Payne, 9 F. 4th 646, 653 (CA8 2021) (similar). Nor is there a barrage of Atkins cases involving multiple IQ scores; in the 12 years since Hall v. Florida, 572 U. S. 701, was decided, Smith’s counsel identifies only 43 Atkins cases across the country in which courts evaluated multiple IQ scores. Brief for Re- spondent 9, and n. 1.4 —————— 3 Contrary to the principal dissent’s assertion, I am not “shifting the burden to Alabama.” Post, at 21 (opinion of ALITO, J.). All agree that an Atkins claimant has the burden to prove that he is intellectually disa- bled. Rather, I explain only that the way this case was litigated renders it inappropriate for this Court to adopt any specific rule about how mul- tiple IQ scores must be assessed in part because Alabama has not urged one here or below. 4 Smith notes that in addition to the 43 cases, another 13 cases may have involved multiple IQ scores but “were either resolved on grounds unrelated to intellectual capacity or arose in a procedural posture . . . 12 HAMM v. SMITH SOTOMAYOR, J., concurring The guidance the principal dissent wishes to provide ap- pears to be, in part, that courts should consult the methods outlined in the American Psychological Association’s Hand- book of Intellectual and Development Disabilities (APA Handbook). Post, at 8. It is hard to imagine, however, that courts need this lesson, given that this Court’s cases have repeatedly explained that “[i]n determining who qualifies as intellectually disabled, it is proper to consult the medical community’s opinions,” Hall, 572 U. S., at 710, including “leading diagnostic manuals,” Moore v. Texas, 581 U. S. 1, 13 (2017); see Atkins, 536 U. S., at 318 (considering the medical community’s framework). The principal dissent apparently seeks to go further and wants this Court to provide more granular guidance about which specific methods of assessing multiple scores are ac- ceptable. Post, at 8–10. As described above, this Court can- not differentiate between methods because these various methods were not raised in the litigation below. Proceeding without a more developed record or lower- court opinions is especially perilous. That is because the differences between methods used to assess multiple IQ scores raise complicated questions on which even experts may disagree. As one example, the principal dissent, citing several studies, argues that “when an individual has multi- ple IQ scores, the ‘higher scores are likely to be more indic- ative’ of a person’s intelligence than the lower scores.” Post, at 11. Yet, the American Association on Intellectual and Developmental Disabilities (AAIDD) explains that “when IQ scores are all close to the boundary of intellectual disa- bility, the ‘true’ score may actually be even lower than the reported scores.” Brief for AAIDD et al. as Amici Curiae (AAIDD Brief ) 26. Due to the statistical concept of —————— distinct from the Atkins analysis.” Brief for Respondent 9, and n. 1; cf. post, at 7 (similarly citing Smith’s appendix but claiming that multiple IQ scores arose in 56 cases). Cite as: 608 U. S. ____ (2026) 13 SOTOMAYOR, J., concurring regression to the mean, the AAIDD elaborates, when an in- dividual’s scores are “grouped far away from the mean score of 100 used on most IQ tests[,] it is a statistical indicator that the individual’s ‘true’ score is likely to be even farther away from the mean.” Ibid. (emphasis deleted); see also D. Watson, Intelligence Testing, in The Death Penalty and In- tellectual Disability 124 (E. Polloway ed. 2015) (“[I]t is in- appropriate to simply accept, in a rote fashion, [a] higher score in the false belief that one can never score higher than their true IQ but can always score poorer in the face of lim- ited effort”). There is no reason for this Court to leapfrog the experts, state courts, and federal lower courts to provide conclusive guidance at this level of detail in the first in- stance. Thus, for the reasons given above, the Court is correct to- day to dismiss this case as improvidently granted. III Despite the principal dissent’s professed concern that lower courts lack sufficient guidance from this Court to an- alyze multiple IQ scores in general, it seems that the core of the dissent’s dissatisfaction is rather with the District Court’s specific conclusion in this case that Smith is intel- lectually disabled and thus cannot be executed. See post, at 10. Even on these case-specific grounds, the dissent is mis- taken. I therefore write to explain why the District Court’s holistic method of reviewing multiple IQ scores is consistent with this Court’s precedents, the medical community’s di- agnostic framework, and Alabama state law. Furthermore, the District Court’s factual finding that Smith has signifi- cantly subaverage intellectual functioning, and its ultimate conclusion that Smith is intellectually disabled, is neither properly before the Court nor clearly erroneous.5 —————— 5 The principal dissent spends considerable time attacking the Elev- enth Circuit’s initial decision in 2024 as adopting a “one-low-score 14 HAMM v. SMITH SOTOMAYOR, J., concurring A To start, the principal dissent claims that the lower courts misinterpreted Hall and Moore. They did not. This Court has not previously addressed the method by which “courts should evaluate multiple IQ scores,” Hamm, 604 U. S., at 2, but it has confronted several cases involving multiple scores. The District Court’s holistic review below was consistent with those precedents. In Hall v. Florida, 572 U. S. 701, the Atkins claimant had seven valid scores between 71 and 80, and Florida sought to execute him based on Florida precedent requiring an IQ score below 70 before allowing additional evidence of intel- lectual disability. 572 U. S., at 707.6 The lower courts had denied relief, but this Court reversed, reasoning that “Flor- ida’s rule disregard[ed] established medical practice in two interrelated ways.” Id., at 712. First, “[i]t [took] an IQ score as final and conclusive evidence of a defendant’s intellec- tual capacity, when experts in the field would consider other evidence.” Ibid. Second, it “relie[d] on a purportedly scientific measurement of the defendant’s abilities, his IQ score, while refusing to recognize that the score is, on its own terms, imprecise.” Ibid. The Court acknowledged that “the analysis of multiple IQ scores jointly is a complicated endeavor,” but that “[e]ven when a person has taken multi- ple tests, each separate score must be assessed using the [standard error of measurement].” Id., at 714. In reaching this conclusion, the Court observed that be- cause a given IQ “test itself may be flawed, or administered —————— approach.” See post, at 10–15. This Court, however, vacated that opin- ion in the per curiam and asked the Eleventh Circuit to clarify whether it used a one-low-score approach or a holistic approach. Hamm v. Smith, 604 U. S. 1 (2024) (per curiam). The Eleventh Circuit’s opinion on re- mand, in which it clarified that it had employed a holistic approach, is the decision on which the dissent should be focusing. 6 Hall had nine total IQ scores, but two were excluded by the sentenc- ing court for evidentiary reasons. Hall, 572 U. S., at 707. Cite as: 608 U. S. ____ (2026) 15 SOTOMAYOR, J., concurring in a consistently flawed manner, multiple examinations may result in repeated similar scores, so that even a con- sistent score is not conclusive evidence of intellectual func- tioning.” Ibid. From this, the Court reasoned that a court may not refuse to consider additional evidence beyond IQ scores, such as evidence of “the defendant’s failure or ina- bility to adapt to his social and cultural environment, in- cluding medical histories, behavioral records, school tests and reports, and testimony regarding past behavior and family circumstances,” if “the medical community accepts that [such] evidence can be probative of intellectual disabil- ity, including for individuals who have an IQ test score above 70.” Id., at 712. Thus, the Court held that Hall must “have the opportunity to present evidence of his intellectual disability, including deficits in adaptive functioning over his lifetime,” even though his seven IQ scores were all above 70. Id., at 724. Moore v. Texas, 581 U. S. 1, also involved an Atkins claim- ant with multiple valid scores: a 74 and a 78. See 581 U. S., at 10.7 Applying Hall, the Court reasoned that “Moore’s score of 74, adjusted for the standard error of measurement, yields a range of 69 to 79,” and “[b]ecause the lower end of Moore’s score range falls at or below 70, the [Texas court] had to move on to consider Moore’s adaptive functioning” and could not “end the intellectual-disability inquiry, one way or the other, based on [the] IQ score” alone. 581 U. S., at 14–15. The principal dissent claims that the District Court con- travened Moore by “deflat[ing] its estimate of Smith’s IQ based on details about his” adaptive deficits. Post, at 16. That misunderstands both the Court’s decision in Moore and the District Court’s decision below. —————— 7 Moore had seven total IQ scores, but the Texas Court of Criminal Ap- peals had “[r]eject[ed] as unreliable five of the seven IQ tests” and con- sidered only the scores of 74 and 78. Moore, 581 U. S., at 10. 16 HAMM v. SMITH SOTOMAYOR, J., concurring In Moore, the Texas courts had discounted the lower end of the standard error range for Moore’s score of 74 because he “was likely exerting poor effort and experiencing depres- sion at the time the test was administered.” 581 U. S., at 25 (ROBERTS, C. J., joined by THOMAS and ALITO, JJ., dis- senting). The Court rejected that reasoning because “the presence of other sources of imprecision in administering the test to a particular individual . . . cannot narrow the test-specific standard-error range.” Id., at 15 (majority opinion). The Court held that, “in line with Hall, . . . courts [must] continue the inquiry and consider other evidence of intellectual disability where an individual’s IQ score, ad- justed for the test’s standard error, falls within the clini- cally established range for intellectual-functioning defi- cits.” Id., at 15. Because Moore had a score of 74, which “yield[ed] a range of 69 to 79,” the Court “requir[ed] the [Texas court] to move on to consider Moore’s adaptive func- tioning in light of his IQ evidence.” Id., at 14. Here, the District Court did not discount the lower or higher end of the standard-error range for Smith’s scores because of his adaptive deficits; rather, it accepted the full ranges as reflective of what Smith’s IQ was likely to be. See Pet. App. 70a (“Smith did not consistently score so high that the Court is confident that . . . the standard error for the tests can be disregarded”); id., at 68a (“It remains clear that the Court should consider the standard error inherent in IQ tests”). It considered all of Smith’s scores and their respec- tive standard errors, some of which fell into the clinically established range for intellectual-functioning deficits, and concluded that “additional evidence must be considered, in- cluding testimony on [Smith’s] adaptive deficits[,] to deter- mine whether Smith is intellectually disabled.” Id., at 74a. That is the same analysis that Hall endorsed and that Moore undertook. The District Court did not deflate a par- ticular score, but instead concluded, based on error ranges Cite as: 608 U. S. ____ (2026) 17 SOTOMAYOR, J., concurring and other evidence of cognitive function, that Smith’s intel- lectual functioning is significantly subaverage. Thus, in both Hall and Moore, this Court confronted At- kins claimants with multiple scores above 70 (and none be- low 70), yet still held that courts should consider the scores in light of “additional evidence of intellectual disability, in- cluding testimony regarding adaptive deficits.” Hall, 572 U. S., at 723. At no point did the Court require, or even suggest, that courts must analyze the scores by combining them using any specific method that the principal dissent contends is necessary. The District Court’s holistic ap- proach was thus squarely in line with Hall and Moore. B The principal dissent also claims that the District Court’s holistic approach “contravened psychology” and “statistics.” Post, at 2. The District Court’s analysis, however, was en- tirely consistent with “the medical community’s diagnostic framework.” Hall, 572 U. S., at 721. When a person has multiple IQ scores, the APA Handbook explains that “clini- cians may benefit from evaluating the 95% confidence in- tervals for each score and collectively interpreting the com- plete set of scores using clinical judgment.” R. Floyd, R. Farmer, W. Schneider, & K. McGrew, Theories and Meas- urement of Intelligence, in 1 APA Handbook of Intellectual and Developmental Disabilities 415 (L. Glidden ed. 2021). The District Court here evaluated Smith’s scores in light of their confidence intervals and took into account the clinical judgment of the experts who each interpreted those scores. See Brief for American Psychological Association et al. as Amici Curiae 22 (APA Brief) (stating that the decision be- low is “fully consistent” with its clinical principles). Fur- ther, the consensus within the medical community is that there is not one “single, mandatory empirical method,” or one set of mandatory methods, for “considering multiple scores” because clinicians must consider the “validity of 18 HAMM v. SMITH SOTOMAYOR, J., concurring each test score and the convergence of that score with other scores and qualitative information.” AAIDD Brief 24.8 Moreover, the District Court’s consideration of adaptive deficits is consistent with the consensus within the medical community, which has made clear that the existence of mul- tiple IQ scores above 70 does not necessarily end the inquiry entirely. Both the APA and the AAIDD emphasize that “IQ test scores cannot stand alone” and “must be considered alongside other data that inform a clinician’s assessment both of intellectual functioning and the other diagnostic cri- teria.” Id., at 5; American Psychiatric Association, Diag- nostic and Statistical Manual of Mental Disorders (DSM) p. 42 (5th ed. text rev. 2022) (“[U]sing [IQ scores] as the sole criteria for the diagnosis of an intellectual developmental disorder is insufficient”). As Hall emphasized, “[i]t is not sound to view a single factor,” such as IQ scores, “as dispos- itive of a conjunctive and interrelated assessment,” and “ ‘[a] person with an IQ score above 70 may have such severe adaptive behavior problems . . . that the person’s actual functioning is comparable to that of individuals with a lower IQ score.’ ” 572 U. S., at 723 (quoting DSM–5, p. 37 (5th ed. 2013)). Therefore, according to medical consensus, when IQ scores are “close to the boundary of intellectual disability,” a “clinician must conduct a detailed review of qualitative reports of the individual’s skills and behavior ‘focusing heavily on the functional assessment of what the person actually does’ and on how the person interacts with the environment . . . to create the most accurate picture of —————— 8 The principal dissent claims that the Court’s failure to provide guid- ance today will result in Atkins proceedings being “little more than bat- tles of experts” and that “[w]hether a defendant lives or dies will hinge on which expert a judge finds more credible.” Post, at 22. It is unclear how the dissent’s approach changes the relative importance of expert tes- timony, given that one of the methods it deems “reasonable” is allowing “an expert witness to . . . make a judgment call about the ‘central ten- dency’ of a defendant’s various scores.” See post, at 9–10. Cite as: 608 U. S. ____ (2026) 19 SOTOMAYOR, J., concurring the person’s day-to-day intellectual functioning.” AAIDD Brief 28 (citing R. Schalock & R. Luckasson, Clinical Judg- ment 29 (2d ed. 2014)); see also AAIDD Brief 28–29 (collect- ing additional citations). The District Court was thus fol- lowing the framework of the medical community, endorsed by this Court’s precedents, when it found that although Smith’s IQ scores made this a “close case,” Smith had proven by a preponderance of the evidence that he had sig- nificantly subaverage intellectual functioning. Pet. App. 91a, 96a.9 C The principal dissent further claims that whether the District Court’s analysis comported with Alabama law does not bear upon whether Smith’s death sentence violated the Constitution. Post, at 19–20. Whether Smith’s execution would violate the Eighth Amendment under Atkins, how- ever, is dependent on Alabama’s definition of intellectual disability because Atkins “ ‘le[ft] to the State[s] the task of developing appropriate ways to enforce [this] constitutional restriction.’” 536 U. S., at 317 (second alteration in origi- nal); see also Brumfield v. Cain, 576 U. S. 305, 308, 314 (2015) (applying state-law definition to determine whether claimant was intellectually disabled for Atkins purposes). The parties here have rightly proceeded on this under- standing. Brief for Petitioner 23; Brief for Respondent 39; Brief for United States as Amicus Curiae 25; see also —————— 9 Despite the principal dissent’s selective quotation of the APA’s and AAIDD’s briefs, post, at 18, n. 6, neither organization contends that a court’s analysis of intellectual disability must perfectly mirror a clini- cian’s. Post, at 18, n. 6. Both organizations agree with this Court’s state- ment in Hall that “[t]he legal determination of intellectual disability is distinct from a medical diagnosis, but it is informed by the medical com- munity’s diagnostic framework.” 572 U. S., at 721; see APA Brief 5–6 (explaining that “scientific and professional consensus should inform the resolution of Atkins claims, but it is not unique to or tailored for the death penalty context”); AAIDD Brief 8–9 (similar). 20 HAMM v. SMITH SOTOMAYOR, J., concurring Petitioner’s Post-Hearing Brief, ECF Doc. 129, p. 2 (“[F]ederal courts must look to and apply Alabama’s defini- tion of intellectual disability”). Moreover, the District Court’s holistic analysis comports with Alabama law, which has no statute or Alabama Su- preme Court decision prescribing how courts must consider multiple IQ scores. See Thomas v. Allen, 607 F. 3d 749, 757 (CA11 2010) (“There is no Alabama case law stating that a single IQ raw score, or even multiple IQ raw scores, above 70 automatically defeats an Atkins claim when the totality of the evidence (scores) indicates that a capital offender suf- fers subaverage intellectual functioning”). Alabama appel- late courts instead recognize that “a court should look at all relevant evidence in assessing an intellectual-disability claim and that no one piece of evidence, such as an IQ test score, is conclusive as to intellectual disability.” Reeves v. State, 226 So. 3d 711, 729 (Ala. Crim. App. 2016). “Conflict- ing expert testimony” with respect to an Atkins claimant’s intellectual functioning “ ‘is always a question for the finder of fact to determine.’ ” 226 So. 3d., at 741. The District Court’s analysis here fully comported with these principles. D At bottom, the principal dissent’s central complaint with the lower courts’ decisions is not truly with the method by which the District Court analyzed the scores. Rather, the dissent looks at Smith’s five scores at face value and cannot fathom that Smith has significantly subaverage intellectual functioning. The Court rightly decides not to “upset the considered judgment[s] of the forensic psychologist[s] that the factfinding court deemed the most credible based on [the dissent’s] own interpretation of a few sentences excised from medical texts.” Moore, 581 U. S., at 33 (ROBERTS, C. J., joined by THOMAS and ALITO, JJ., dissenting). The District Court’s factual determination also cannot be reversed unless it is clearly erroneous. “If the district Cite as: 608 U. S. ____ (2026) 21 SOTOMAYOR, J., concurring court’s account of the evidence is plausible in light of the record viewed in its entirety,” an appellate court “may not reverse it even though convinced that had it been sitting as the trier of fact, it would have weighed the evidence differ- ently.” Anderson v. Bessemer City, 470 U. S. 564, 573–574 (1985). When factual findings “are based on determinations regarding the credibility of witnesses,” such as the experts here, clear-error review “demands even greater deference to the trial court’s findings.” Id., at 575. Indeed, three of the dissenting Justices have previously agreed that “ ‘[b]ecause there often is no single, accurate psychiatric conclusion,’ ” it is “importan[t]” to allow the “ ‘primary factfinder[ ]’ to ‘re- solve differences in opinion . . . on the basis of the evidence offered by each party.’ ” Moore, 581 U. S., at 32 (ROBERTS, C. J., joined by THOMAS and ALITO, JJ., dissenting) (third alteration and ellipsis in original). Here, neither Alabama nor the United States seriously contends that the District Court’s finding was clearly erro- neous. For good reason: It was not. The District Court held an evidentiary hearing and carefully weighed the evidence, including the raw IQ scores, each score’s standard error range, expert testimony about interpreting those scores, and much more. The court ultimately found that Smith has significantly subaverage intellectual functioning and is in- tellectually disabled. On my review of the record, this de- termination was correct, or, at the very least, plausible. See APA Brief 22 (“The IQ test scores in this case fall comforta- bly within the range within which a clinician could reason- ably conclude . . . that Smith satisfied” the intellectual- functioning prong of Alabama’s definition). In the principal dissent’s view, that determination was incorrect. Either way, this Court is not as equipped as the District Court to appreciate all the evidence. In any event, this Court did not grant certiorari to decide whether the Eleventh Circuit properly applied a preponder- ance of the evidence standard. Nor did the Court grant 22 HAMM v. SMITH SOTOMAYOR, J., concurring certiorari to decide whether the District Court’s factual de- termination was clearly erroneous. Given that, the Court today rightly declines to reweigh the evidence underlying the District Court’s determination. Ultimately, as this Court has recognized, “[i]ntellectual disability is a condition, not a number” and the “ ‘the diag- nosis of [intellectual disability] is intended to reflect a clin- ical judgment rather than an actuarial determination.’ ” Hall, 572 U. S., at 723 (second alteration in original). In close cases such as this one, the inquiry may well involve a substantial amount of evidence, but that inquiry is never- theless critical to avoid the “unacceptable risk that persons with intellectual disability will be executed” contrary to the Eighth Amendment. Id., at 704. * * * In cases presenting multiple IQ scores, courts should con- tinue to consider multiple IQ scores in light of this Court’s precedents and “ ‘the views of medical experts.’ ” Moore, 581 U. S., at 5. If a conflict among the States or lower courts emerges and a case properly presents the issue, it may be appropriate for this Court to weigh in with more specific guidance about the permissible method or methods by which courts must analyze such scores. The Court rightly decides that it is inappropriate to do so in this case. I there- fore concur in the decision to dismiss the writ of certiorari as improvidently granted. Cite as: 608 U. S. ____ (2026) 1 THOMAS, J., dissenting SUPREME COURT OF THE UNITED STATES _________________ No. 24–872 _________________ JOHN Q. HAMM, COMMISSIONER, ALABAMA DE- PARTMENT OF CORRECTIONS, PETITIONER v. JOSEPH CLIFTON SMITH ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE ELEVENTH CIRCUIT [May 21, 2026] JUSTICE THOMAS, dissenting. In 1997, Joseph Clifton Smith murdered Durk Van Dam. The trial court, accepting the jury’s recommendation, sen- tenced Smith to death. Smith lost his appeal in 2001. But a year later, in Atkins v. Virginia, 536 U. S. 304 (2002), this Court held for the first time that convicted murderers like Smith cannot be executed if they are deemed insufficiently intelligent, which the Court suggested would require that they had an IQ of 70 or below. Id., at 308–309, and n. 3, 316–321. Such persons could not be executed, the Court said, even if they “know the difference between right and wrong,” even if they “are competent to stand trial,” and even if they are intelligent enough to deserve other “criminal sanctions.” Id., at 318. The Court did not pretend that the Constitution had ever been understood to impose such a rule. Id., at 340–341 (Scalia, J., dissenting). Just 13 years earlier, it had acknowledged the opposite. Penry v. Lynaugh, 492 U. S. 302, 330–335 (1989). But the Court set aside the Constitution and imposed a new rule anyway. The result was predictable: To avoid execution, Smith tried to convince courts that he is not intelligent enough to be executed. Today, the Court rewards Smith’s efforts. It dismisses the State’s petition challenging the lower courts’ vacatur of 2 HAMM v. SMITH THOMAS, J., dissenting his death sentence under Atkins. But Smith is not insuffi- ciently intelligent to be executed. He can read at an 11th- grade level. He took five IQ tests and did not once receive a score of 70 or below, instead scoring 75, 74, 72, 78, and 74. The lower courts held that he could not be executed based only on the hypothetical possibility that these IQ scores were all wrong and that his IQ is in fact 70 or below. I join JUSTICE ALITO’s opinion because it persuasively explains why that approach is statistically indefensible. As this case shows, though, Atkins has bred only confu- sion and absurdity. Nothing in the text or history of the Constitution supports Atkins. It should be overruled. I A In 1997, just two days after being released from custody for burglary, Joseph Clifton Smith murdered Durk Van Dam. Smith plotted with his friend Larry Reid to rob Van Dam, whom they heard was carrying cash. They lured Van Dam to an isolated location. There, Smith and Reid beat Van Dam and attacked him with a power saw, eventually killing him. Smith and Reid then divided the money that they stole from Van Dam. Smith told one person that he had hit Van Dam on the head and cut him, and he told an- other that he had hit, cut, and stabbed Van Dam. The police discovered Van Dam’s badly mutilated body in a wooded area. He had injuries from the saw on his neck, shoulder, and back. He also suffered a hemorrhage under his scalp, broken ribs, and brain swelling. The broken ribs caused one of Van Dam’s lungs to collapse. A forensic pathologist testified that 35 blunt-force injuries caused his death. He died trying to defend himself. A jury convicted Smith of murdering Van Dam and rec- ommended that he be sentenced to death. The trial court found three aggravating circumstances and no significant mitigating circumstances. The three aggravating Cite as: 608 U. S. ____ (2026) 3 THOMAS, J., dissenting circumstances were that Smith was on leave from his term of imprisonment for burglary at the time of the murder; that the murder occurred during a robbery; and “that the murder was especially heinous, atrocious, or cruel.” Smith v. State, 795 So. 2d 788, 797, n. 1, 841–842 (Ala. Crim. App. 2000) (per curiam). As for mitigating circumstances, the trial court rejected Smith’s arguments that his bad upbring- ing or lack of intelligence justified a sentence other than death. It explained that Smith’s upbringing did not “ ‘jus- tify a[n] act of senseless rage directed at an innocent human being.’ ” Id., at 841. And it found that Smith’s “ ‘lack of in- telligence is not an excuse for murder, especially in the con- text of this case.’ ” Ibid. Smith “knew he had,” in his words, “F___ Up,” and, “while in control [of himself,] he savagely attacked” Van Dam. Ibid. (internal quotation marks omit- ted). The trial court accepted the jury’s recommendation and sentenced Smith to death. The Alabama Court of Criminal Appeals affirmed the conviction and death sentence. Id., at 842. Both the Su- preme Court of Alabama and this Court denied certiorari. Ex parte Smith, 795 So. 2d 842 (2001); Smith v. Alabama, 534 U. S. 872 (2001). B A year later, this Court’s decision in Atkins opened a new avenue for convicted murderers such as Smith to challenge their death sentences. Atkins arose out of another robbery and murder. Daryl Atkins and a friend abducted and robbed a United States airman named Eric Nesbitt. 536 U. S., at 307; id., at 338 (Scalia, J., dissenting). After abducting and robbing him, Atkins shot Nesbitt eight times, killing him. Id., at 307 (majority opinion). The jury found Atkins guilty of capital murder. At the penalty phase, the jury heard “extensive evidence” of Atkins’s “alleged mental retardation,” includ- ing testimony from a psychologist that Atkins “was ‘mildly 4 HAMM v. SMITH THOMAS, J., dissenting mentally retarded’ ” with an “IQ of 59,” and testimony from another psychologist who concluded that Atkins was “of ‘av- erage intelligence, at least.’ ” Id., at 308–309; id., at 338– 339 (Scalia, J., dissenting). The jury also learned that At- kins had “16 prior felony convictions for robbery, attempted robbery, abduction, use of a firearm, and maiming.” Id., at 339. Atkins had previously attacked a different victim with a gun, “knocked her to the ground, and then helped her up, only to shoot her in the stomach.” Ibid. After hearing all the evidence, the jury sentenced Atkins to death. Ibid.; id., at 309 (majority opinion). This Court held that Atkins’s sentence was unconstitu- tional “cruel and unusual punishment” under the Eighth Amendment. Id., at 311, 321. The Court said that the Eighth Amendment prohibits all “ ‘[e]xcessive’ sanctions.” Id., at 311. Whether a punishment was excessive, the Court said, depended not on the “standards that prevailed . . . when the Bill of Rights was adopted,” but on the “‘evolving standards of decency that mark the progress of a maturing society.’ ” Id., at 311–312 (quoting Trop v. Dulles, 356 U. S. 86, 100–101 (1958)). According to the Court, “the American public, legislators, scholars, and judges ha[d] deliberated” over whether “the death penalty should ever be imposed on a mentally retarded criminal” and decided that it should not. Atkins, 536 U. S., at 307, 313–317. The Court con- cluded that there was a “national consensus” against im- posing the death penalty on the mentally retarded, largely because 18 States barred it. Id., at 314–316. The Court itself agreed with this supposed “consensus”; it was “not persuaded that the execution of mentally retarded crimi- nals will measurably advance the deterrent or the retribu- tive purpose of the death penalty.” Id., at 321. The Atkins Court promised that it would allow States to define mental retardation. It admitted that there was “se- rious disagreement” about “determining which offenders are in fact retarded.” Id., at 317. Accordingly, the Court Cite as: 608 U. S. ____ (2026) 5 THOMAS, J., dissenting decided to “ ‘leave to the State[s] the task of developing ap- propriate ways to enforce the constitutional restriction upon [their] execution of sentences.’ ” Ibid. So, despite the Court’s holding that the Eighth Amendment forbids “the ex- ecution of mentally retarded offenders,” whether an of- fender was “mentally retarded” would depend on state rules. Ibid. Still, the Court suggested that someone with an IQ above 70 could not be mentally retarded for Eighth Amendment purposes. See id., at 308, n. 3, 316–318; Brumfield v. Cain, 576 U. S. 305, 345–346 (2015) (THOMAS, J., dissenting). The Court drew from “clinical definitions of mental retar- dation” that include three necessary elements. Atkins, 536 U. S., at 318. First, the offender must have “ ‘subaverage intellectual functioning’ ” based primarily on IQ tests. Id., at 308, n. 3, 318. Second, he must have “significant limita- tions in adaptive skills such as communication, self-care, and self-direction.” Id., at 318. And third, these limitations must have manifested before age 18. Ibid. “ ‘Mild’ mental retardation,” the Court explained, “is typically used to de- scribe people with an IQ level of 50–55 to approximately 70.” Id., at 308, n. 3. Apparently drawing on that category’s upper limit, the Court noted that “only five [States] ha[d] executed offenders possessing a known IQ less than 70 since” 1989. Id., at 316. It was thereafter reasonable to understand Atkins to allow States to execute people with IQs above 70. See Brumfield, 576 U. S., at 345–346 (THOMAS, J., dissenting). C In the years since, the Alabama courts have faithfully ap- plied that understanding of Atkins. When called to imple- ment it, they observed that other “states with statutes pro- hibiting the execution of a mentally retarded defendant require that a defendant, to be considered mentally re- tarded, must have significantly subaverage intellectual 6 HAMM v. SMITH THOMAS, J., dissenting functioning (an IQ of 70 or below), and significant or sub- stantial deficits in adaptive behavior” “before the defendant reached age 18.” Ex parte Perkins, 851 So. 2d 453, 456 (Ala. 2002); see also Ex parte Smith, 213 So. 3d 214, 224 (Ala. 2003). Consistent with Atkins, the Alabama courts held that “[a]ll three factors must be met in order for a person to be classified as mentally retarded for purposes of an Atkins claim.” Smith v. State, 213 So. 3d 239, 248 (Ala. 2007). And, consistent with Atkins, they held that the prisoner has the burden to prove that he is mentally retarded by a pre- ponderance of the evidence. 213 So. 3d, at 252. When it came to applying Atkins to Smith, the Alabama courts had no trouble recognizing that he did not satisfy the first requirement and therefore is not mentally retarded. The Court of Criminal Appeals explained that, by 2008, Smith had scored 75, 74, and 72 on three IQ tests. Smith v. State, 71 So. 3d 12, 19–20 (2008). Though his lowest score suggested that Smith’s true IQ “could be . . . as low as 69” taking account of the error range for that score, it could also be “as high as 75.” Id., at 19. Smith asked the court “to apply that margin of error to conclude that . . . he is mentally retarded.” Id., at 20. But the court rejected that argument, which would require “expanding the definition of mentally retarded” to include people whose true IQ is likely above 70. Ibid. Unable to persuade the Alabama courts that he was men- tally retarded, Smith sought habeas relief in federal court, arguing that the Alabama courts unreasonably applied At- kins. See 28 U. S. C. §2254(d). The District Court initially denied habeas relief for the straightforward reason that the Court of Criminal Appeals did not act unreasonably when it refused to “reduc[e]” Smith’s lowest “IQ score of 72 such that [it] would . . . fall within the mental retardation range.” Smith v. Thomas, Civ. Action No. 05–0474 (SD Ala., Sept. 30, 2013), ECF Doc. 59, pp. 61–62. Smith’s own expert, the court explained, testified that his scores were at Cite as: 608 U. S. ____ (2026) 7 THOMAS, J., dissenting best close “ ‘to those individuals who would be considered mentally retarded’ ”—a conclusion that “is incompatible with a determination that Smith is mentally retarded him- self.” Id., at 60 (emphasis deleted). And, the court ob- served, “every IQ test administered to Smith during his de- velopmental period yielded an unadjusted score above the cutoff for mental retardation.” Id., at 61, n. 24. The Eleventh Circuit disagreed. It thought that it was “unreasonable” to suppose that Smith did not have signifi- cantly subaverage intelligence. Smith v. Campbell, 620 Fed. Appx. 734, 750–751 (2015). The court ordered the Dis- trict Court to give Smith a new hearing for reconsideration of his Atkins claim de novo. 620 Fed. Appx., at 751–752. D Smith would go to his hearing armed with new decisions of this Court. In Hall v. Florida, 572 U. S. 701 (2014), this Court acknowledged that States can require defendants to show an IQ of 70 or below in order to establish that they are mentally retarded, but held that States must in some man- ner account for the test’s standard error range. States may, “consistently with Atkins,” define mental retardation to re- quire an IQ of “70 points” or below if they consider “the IQ test’s standard error of measurement.” Id., at 711–712. Under Florida’s test, as the Court understood it, a prisoner with a single IQ score of 71 whose error range included 70 would be conclusively not mentally retarded even if “other evidence” suggested that his “true IQ” was in fact 70 or be- low. Id., at 712, 713. The Court thought that this “strict IQ test score cutoff of 70” was impermissible because it “ig- nores the inherent imprecision of ” IQ tests and “risks exe- cuting a person who suffers from intellectual disability.” Id., at 712–713, 723. Hall therefore held it unconstitutional to treat as decisive a single above-70 score whose error range includes 70. Id., at 723–724. In imposing this new 8 HAMM v. SMITH THOMAS, J., dissenting constitutional rule, Hall relied on “medical experts” and “professional studies.” Id., at 709–710. Hall did not tell courts what to do when low scores whose error ranges touch 70 are paired with multiple higher scores whose error ranges do not. The Court, as in Atkins, left States without guidance: “[T]he analysis of multiple IQ scores jointly is a complicated endeavor.” 572 U. S., at 714. Exactly how courts should weigh multiple IQ scores re- mained unclear. See id., at 742–743 (ALITO, J., dissenting). The next two decisions further walked back Atkins’s promise to allow States to define mental retardation and instead outsourced the project to clinical practice. In Moore v. Texas, 581 U. S. 1 (2017) (Moore I), the Court reiterated that “courts must account for” a test’s error range “where an IQ score is close to, but above, 70” because “other evi- dence” may show that “ ‘[the] individual’s true IQ score’ ” is 70 or less. Id., at 13–15. The Court also told lower courts not to “overemphasiz[e] . . . per