New important Atkins SCOTUS decision on fall 2025 docket: How to evaluate and interpret multiple IQ scores in Atkins cases (Hamm[AL] v Smith)?

 This fall 2025, the Supreme Court of the United States (SCOTUS) will be hearing a case related to intelligence testing in the context of Atkins intellectual disability (ID) death penalty cases. The case is Hamm v Smith.

The question before SCOTUS is :  Whether and how courts may consider the cumulative effect of multiple IQ scores in assessing Atkins claims (in the context of diagnosis ID in death penalty cases)?

Note.  In order to save space and time, instead of writing “general intelligence” or “general intellectual functioning” every time, I use the abbreviation “IQ”.

The respondent (Joseph Smith) has five IQ test scores from comprehensive IQ tests.  He obtained two scores of 75 and 74 during the developmental period (before age 22), and three scores of 72, 78, and 74 between the ages of 28 and 46.  

This case is important for assessment professionals who conduct intelligence testing in general, and potential ID diagnostic cases (Atkins cases in particular).  I find this SCOTUS case particularly interesting given that in 2021, after the 2021 release of the latest official AAIDD manual (Intellectual disability: Definition, diagnosis, classification, and systems of supports), I published a critique where I specifically stated, as one weakness of the new AAIDD manual that “…many high-stakes ID cases often include case files that include multiple IQ scores across time or from different IQ tests. Some form of guidance, at minimum in a passing reference, to the issues of the convergence of indicators and IQ score exchangeability would have been useful. Users will need to go beyond the AAIDD manual for guidance (see Floyd et al., 2021; McGrew, 2015; and Watson, 2015)” (click here to download and read this critique).

All official petitioner and respondent legal briefs (and amicus briefs) have now been published at the SCOTUS blog as of yesterday.  The number of documents posted on the SCOTUS docket are many.  To help the reader better determine which documents are most critical (the final briefs), instead of clicking away on the various links at the SCOUTUS blog, I’ve organized the petitioner and respondent brief links below.

If you prefer to not wade through all the briefs (it is not for everyone), I would encourage practicing assessment professionals read the three respondent-related briefs.  The points made are relevant to all who conduct intellectual assessments.  As a potential conflict of interest notice, I (Dr. Kevin McGrew), together with Dr. Joel Schneider and Dr. Cecil Reynolds (as noted on page three for the APA amicus brief), were consultants to APA in the drafting of that brief.  This work was performed pro bono. I, at a minimum, suggest reading all the respondent briefs.  If time permits, I would also suggest reading the petitioner’s Alabama brief and the US Justice Department Solicitor General’s brief to better understand the petitioner and respondent positions re Hamm v Smith. 

Petitioner briefs

• The state of Alabama brief.  Alabama is the petitioner.  That is, if you want to read why the State of Alabama asked SCOTUS to hear this case, click on the link provided.
• The Alabama brief also includes a very long appendix for those who want to read the prior courts related testimony from the state and various experts. This is a very long read and is not necessary for readers who only want to understand the legal and professional issues. 
• Supporting amicus brief from the US Justice Department Solicitor General.
• Two supporting briefs from legal groups—the American Legal Foundation and the Criminal Justice Legal Foundation.
• Supporting amicus briefs from other states (Idaho et al.; Kentucky)

Respondent briefs

• Smiths respondent brief.
• Supporting amicus brief from American Psychological Association (APA), American Psychiatric Assocation (ApA), and Alabama APA.
• Supporting amicus brief from AAIDD et al.

Final comment.  Those from school psychology should make note that we three consultants involved in drafting the APA/ApA,AL-APA brief all had our original educational roots in the profession of school psychology.  Furthermore, SP professionals should note the significant number of authoritative references to publications authored by school psychologists in the respondents briefs, as well as in some of the petitioners briefs.  I’ve been doing expert consultation, writing declarations, and testifying in court re: Atkins ID cases since 2009.  Joel Schneider and Cecil Reynolds have also been active in a similar capacity.  There are more psychologists who come from, or are affiliated with, the field of school psychology who have been prominent consultants/experts to lawyers and the courts re Atkins cases.  

Perhaps some of these briefs should be assigned readings (in intellectual assessment courses or special topic seminars) for graduate students being trained in the art and science of intelligence testing and interpretation.

New longitudinal (2 decades) practice effect study

 See post with article info over at sister blog IQs Corner.

IQs Corner: What is (and what is not) clinical judgment in intelligence test interpretation?

What is clinical judgment in intelligence testing?  

This term is frequently invoked when psychologists explain or defend their intelligence test interpretations.  Below is a brief explanation I’ve used to describe what it is…and what it is not, based on several sources.  Schalock and Luckasson’s AAIDD Clinical Judgment book (now in a 2014 revised version) is the best single source I have found that addresses this slippery concept in intelligence testing, particularly in the context of a potential diagnosis of intellectual disability (ID)—it is a recommended reading.

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Clinical judgment is a process based on solid scientific knowledge and is characterized as being “systematic (i.e., organized, sequential, and logical), formal (i.e., explicit and reasoned), and transparent (i.e., apparent and communicated clearly)” (Schalock & Luckasson, 2005, p.1). The application of clinical judgment in the evaluation of IQ scores in the diagnosis of intellectual disability includes consideration of multiple factors that might influence the accuracy of an assessment of general intellectual ability (APA: DSM-5, 2013).  The “unanimous professional consensus that the diagnosis of intellectual disability requires comprehensive assessment and the application of clinical judgment” (Brief of Amici Curiae American Psychological Association, American Psychiatric Association, American Academy of Psychiatry and the Law, Florida Psychological Association, National Association of Social Workers, and National Association of Social Workers Florida Chapter, in Support of Petitioner; Hall v. Florida; S.Ct., No. 12-10882; 2014; p. 8).

The misuse of clinical judgment in the interpretation of scores from intelligence test batteries should not be used as the basis for “gut instinct” or “seat-of-the-pants” impressions and conclusions of the assessment professional (Macvaugh & Cunningham, 2009), or justification for shortened evaluations, a means to convey stereotypes or prejudices, a substitute for insufficiently explored questions, or an excuse for incomplete testing and missing data (Schalock & Luckasson, 2005). Idiosyncratic methods and intuitive conclusions are not scientifically based and have unknown reliability and validity. 

If clinical judgment interpretations and opinions regarding an individual’s level of general intelligence are based on novel or emerging research-based principles, the assessment professional must document the bases for these new interpretations as well as the limitations of these principles and methods. This requirement is consistent with the Standards for Educational and Psychological Testing Standard 9.4 which states:

When a test is to be used for a purpose for which little or no validity evidence is available, the user is responsible for documenting the rationale for the selection of the test and obtaining evidence of the reliability/precision of the test scores and the validity of the interpretations supporting the use of the scores for this purpose (p. 143).

American Educational Research Association, American Psychological Association, & National Council on Measurement in Education (2014).  Standards for educational and psychological testing.  Washington, DC:  Author. 

American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders— Fifth Edition. Washington D.C.:  Author. 

Brief of Amici Curiae American Psychological Association, American Psychiatric Association, American Academy of Psychiatry and the Law, Florida Psychological Association, National Association of Social Workers, and National Association of Social Workers Florida Chapter, in Support of Petitioner; Hall v. Florida; S.Ct., No. 12-10882; 2014; p. 8.

MacVaugh, G. S. & Cunningham, M. D. (2009). Atkins v. Virginia: Implications and recommendations for forensic practice.  The Journal of Psychiatry and Law, 37, 131-187.

Schalock, R. L. & Luckasson, R. (2005). Clinical judgment. Washington, DC: American Association on Intellectual and Developmental Disabilities. 

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Kevin S. McGrew, PhD.

Educational Psychologist

Director 

Institute for Applied Psychometrics (IAP)

www.theMindHub.com

Reevaluating the Flynn effect, and the reversal: Temporal trends and measurement invariance in Norwegian armed forces intelligence scores

Reevaluating the Flynn effect, and the reversal: Temporal trends and measurement invariance in Norwegian armed forces intelligence scores

Open access PDF available from journal Intelligence…click here.

Abstract

Since 1954, the Norwegian Armed Forces have annually administered an unchanged general mental ability test to male cohorts, comprising figure matrices, word similarities, and mathematical reasoning tests. These stable and representative data have supported various claims about shifts in general mental ability (GMA) levels, notably the Flynn effect and its reversal, influencing extensive research linking these scores with health and other outcomes. This study examines whether observed temporal trends in scores reflect changes in latent intelligence or are confounded by evolving test characteristics and specific test-taking abilities in numerical reasoning, word comprehension, and figure matrices reasoning. Our findings, using multiple-group factor analysis and multiple indicator multiple cause (MIMIC) models, indicate that while there was a general upward trend in observed scores until 1993, this was predominantly driven by enhancements in the fluid intelligence task, specifically figure matrices reasoning. Notably, these gains do not uniformly translate to a rise in underlying GMA, suggesting the presence of domain-specific improvements and test characteristic changes over time. Conversely, the observed decline is primarily due to decreases in word comprehension and numerical reasoning tests, also reflecting specific abilities not attributable to changes in the latent GMA factor. Our findings further challenge the validity of claims that changes in the general factor drive the Flynn effect and its reversal. Furthermore, they caution against using these scores for longitudinal studies without accounting for changes in test characteristics.