Court Limits Use of IQ Score in Death Penalty Eligibility

“Intellectual disability is a condition, not a number,” said Supreme Court Justice Anthony Kennedy, declaring that states cannot use a fixed IQ score to determine eligibility for the death penalty but must also include a more complex evaluation of adaptive functioning when evaluating intellectual disability.

In a 5-to-4 decision May 27, the Court ruled in favor of Freddie Lee Hall, convicted in Florida of the rape and murder of a 21-year-old woman in 1978.

“This Court agrees with the medical experts that when a defendant’s IQ test score falls within the test’s acknowledged and inherent margin of error, the defendant must be able to present additional evidence of intellectual disability, including testimony regarding adaptive deficits,” Kennedy wrote. Justices Stephen Breyer, Ruth Bader Ginsburg, Elena Kagan, and Sonia Sotomayor concurred.

“As the majority opinion indicates, there are areas where professional expertise can inform the legislature and the courts so that the decision makers will have the consensus of the field before them in these very important determinations,” said APA President Paul Summergrad, M.D., the Dr. Frances S. Arkin Professor and Chairman of Psychiatry and Professor of Medicine at Tufts University School of Medicine and psychiatrist-in-chief at Tufts Medical Center.

Florida law set an automatic cutoff at an IQ of 70, and Hall had scored at least 71 on several IQ tests. However, Hall’s attorneys said that result failed to account for an inherent five-point error of measurement and ignored recent research findings into intellectual disability.

The court agreed, saying that use of an IQ score alone created an unacceptable and unconstitutional risk that a person with intellectual disability would be executed.

“An IQ score is an approximation, not a final and infallible assessment of intellectual functioning,” wrote Kennedy. “A State that ignores the inherent imprecision of these tests risks executing a person who suffers from intellectual disability.”

The majority’s view quoted heavily from the amicus curiae brief submitted by APA and the American Psychological Association. The brief in turn was grounded in the research underlying DSM-5’s discussion of intellectual disability.

“The Court’s decision in Hall recognizes that criteria for diagnosis of mental disorders—here specifically intellectual disability—should be determined by professional standards, not by the arbitrary decisions of state legislatures,” said Paul Appelbaum, M.D., the Dollard Professor of Psychiatry, Medicine, and Law and director of the Division of Law, Ethics, and Psychiatry at Columbia University College of Physicians and Surgeons, in an interview. “From a court that is often skeptical of psychiatry, this is a major acknowledgment that courts should turn to psychiatry when issues related to the diagnosis of mental disorders arise.”

More specifically, the court accepted the view of intellectual disability as a neurodevelopmental disorder, said neuropsychiatrist James Harris, M.D., a professor of psychiatry and behavioral sciences and pediatrics at Hopkins University, in an interview with Psychiatric News.

“IQ alone is insufficient to assess reason and functioning in real-life situations,” said Harris. Evaluation now must also include conceptual skills, social reasoning, and practical problem-solving abilities.

The Hall case, perhaps inevitably, grew out of gray areas in Atkins v. Virginia (2002). The Court said then that the Eighth and 14th amendments to the Constitution forbade execution of persons with intellectual disability, but left it up to the states to define that term.

The dissenting justices, led by Samuel Alito Jr., said the Hall decision was based not on precedent and society’s “evolving standards of decency” but on the evolving standards of “a small professional elite”—standards that were “likely to result in confusion.”

However, Kennedy noted that not one medical professional had supported Florida’s position.

“We’ve finally gotten to the point where the Supreme Court has acknowledged the role of professional organizations,” said Harris. “This is a victory for science.” ■