Holistic Approach to Multiple IQ Scores for Determining Intellectual Disability in Capital Cases

1. Introduction

This commentary examines the Eleventh Circuit’s per curiam decision in Joseph Clifton Smith v. Commissioner, Alabama Department of Corrections, No. 21-14519, rendered on November 14, 2024, and issued “[Do Not Publish].” The appeal returns on remand from the United States Supreme Court (Hamm v. Smith, No. 23-167, 604 U.S. ___, 2024 WL 4654458 (Nov. 4, 2024)), which asked the Eleventh Circuit to clarify whether its prior affirmation of a district court’s finding of intellectual disability rested solely on the lower bound of a standard‐error range for one IQ score or on a holistic review of multiple IQ tests and expert testimony.

Petitioner‐Appellee Joseph Clifton Smith challenged his death sentence under 28 U.S.C. § 2254, arguing that he is intellectually disabled and thus exempt from execution under the Eighth and Fourteenth Amendments. The State of Alabama, through the Commissioner of the Alabama Department of Corrections, appealed the district court’s grant of habeas relief. The central issue on remand was the proper standard for weighing multiple IQ scores and associated evidence when determining whether a capital defendant meets the diagnostic criteria for intellectual disability.

2. Summary of the Judgment

On remand, the Eleventh Circuit clarified that its earlier decision did not rest solely on the lowest possible IQ score’s standard‐error lower bound (69), but on a “holistic approach to multiple IQ scores that considers the relevant evidence, including as appropriate any relevant expert testimony.” Applying this standard, the court reaffirmed the district court’s factual findings that Smith (1) suffers significantly subaverage intellectual functioning, (2) has substantial adaptive behavior deficits, and (3) manifested these impairments before age 18. Because none of these findings were “clearly erroneous” under the deferential standard of review, the Eleventh Circuit again affirmed the grant of Smith’s § 2254 petition and the vacation of his death sentence.

3. Analysis

3.1. Precedents Cited

  • Atkins v. Virginia, 536 U.S. 304, 321 (2002): Established that executing intellectually disabled individuals violates the Eighth Amendment.
  • Hall v. Florida, 572 U.S. 701 (2014): Held that rigid IQ cutoffs are impermissible; courts must account for standard error of measurement and consider adaptive deficits.
  • Moore v. Texas, 581 U.S. 1 (2017): Reinforced that if a defendant’s IQ range includes scores at or below 70, the court must evaluate adaptive functioning.
  • Ex parte Perkins, 851 So. 2d 453 (Ala. 2002): Alabama’s diagnostic framework for intellectual disability under Atkins, requiring subaverage intellect, adaptive deficits, and onset before age 18.
  • Ledford v. Warden, Ga. Diagnostic & Classification Prison, 818 F.3d 600 (11th Cir. 2016): Discussed standard error in IQ testing and the need for comprehensive evaluation.

These precedents collectively shape the tripartite test: an IQ score of approximately 70 or below (plus error margin), significant deficits in daily living skills, and evidence of onset in the developmental period.

3.2. Legal Reasoning

The court’s reasoning proceeds in two stages:

  1. IQ Assessment Under Standard Error: Recognizing that IQ tests carry a standard error of measurement (commonly ±5 points), the district court identified Smith’s lowest raw score (72) and, accounting for error, found a possible “true IQ” as low as 69. This triggered further inquiry rather than an automatic finding of non‐disability.
  2. Holistic Review of Multiple Scores and Expert Evidence: The court then examined all five IQ scores (75, 74, 72, 78, 74) and competing expert testimony. While Alabama’s expert argued consistency above the disability threshold, the district court found Dr. King’s critique insufficient to negate the possibility of subaverage functioning. The court weighed plausibility, consistency across multiple measures, and adaptive behavior evidence to conclude that Smith meets the intellectual disability criteria under Atkins and Hall.

On clear‐error review, the Eleventh Circuit emphasized the heavy deference owed to district‐court factfinding, upholding all critical findings on Smith’s intellectual functioning and adaptive deficits.

3.3. Impact

This decision provides guidance for lower courts in capital‐case intellectual disability litigations:

  • It rejects any per se rule that the lower bound of one IQ score’s error margin can alone establish intellectual disability.
  • It endorses a holistic, case‐by‐case approach that examines every IQ assessment, the standard‐error ranges, and adaptive behavior evidence in context.
  • It reaffirms the necessity of expert testimony and individual factual inquiry rather than mechanically applying numeric cutoffs.

Future litigants and courts will look to this clarification when debating the weight of multiple IQ results, ensuring consistency with the Supreme Court’s mandates in Hall and Moore.

4. Complex Concepts Simplified

Standard Error of Measurement (SEM)
A statistical margin of error around an IQ test score (often ±5 points). If a subject scores 72, their “true IQ” could be between 67 and 77.
Holistic Approach
Rather than treating one IQ score as dispositive, courts must assess all available test results, error margins, expert evaluations, and evidence of daily‐living skills together.
Adaptive Behavior Deficits
Limitations in practical life areas—communication, social skills, self‐care, work, and community living—that signal real‐world functioning below normative expectations.
Clearly Erroneous Standard
On appeal, a district court’s factual findings are affirmed unless the record compels a conclusion that no reasonable factfinder could reach the same result.

5. Conclusion

In Smith (Eleventh Circuit, 2024), the court fortifies the principle that determining intellectual disability in capital cases requires a nuanced, holistic evaluation of multiple IQ scores, each test’s standard‐error range, expert analyses, and adaptive behavior evidence. It dispels any notion that a single IQ‐score lower‐bound can suffice and underscores the judiciary’s obligation to engage in meticulous factfinding under Atkins, Hall, and Moore. This decision will shape future capital‐punishment litigation by reaffirming that intellectual disability determinations demand individualized, context‐sensitive assessments rather than mechanical numeric thresholds.