Supreme Court Reinforces Ban on Executing the Intellectually Disabled


The United States Supreme Court today held that a Florida law requiring an IQ score below 70 to be considered intellectually disabled (and therefore ineligible for the death penalty) is unconstitutional.

In 2002, the Supreme Court in Atkins v. Virginia held that the Eighth Amendment’s ban on cruel and unusual punishment prohibits imposing the death penalty on intellectually disabled people. The Court wrote that a finding of intellectual disability requires proof of “subaverage intellectual functioning” (low IQ scores), deficits in basic social, academic, and practical skills, and the presence of both conditions before age 18. Adopting well-accepted clinical definitions, the Court wrote that IQ scores under “approximately 70” typically indicate intellectual disability, but left it to the states to work out the details.

States including Florida responded to Atkins by implementing standards for proving intellectual disability that are allowing people to be executed despite the fact that they are intellectually disabled.

In Mr. Hall’s case, despite making earlier findings that he was intellectually disabled, Florida courts decided Mr. Hall could be executed notwithstanding Atkins because his IQ had been measured at slightly above 70 (although there was also evidence that his IQ may be as low as 60). The state court relied on a Florida law enacted before Atkins which created a bright-line cutoff at 70. As Justice Kennedy wrote for the majority in today’s decision, “Florida seeks to execute a man because he scored a 71 instead of 70 on an I.Q. test.”

Mr. Hall argued that bright-line cutoff is unconstitutional because it ignores the standard error of measurement that is part of the clinical definition of intellectual disability. The Supreme Court agreed, holding that “when a defendant’s IQ test score falls within the test’s acknowledged and inherent margin of error” – generally, when a person has an IQ score of 75 or below – “the defendant must be able to present additional evidence of intellectual disability, including testimony regarding adaptive deficits.”

Alabama joins Florida in the minority of states that, by statute or judicial interpretation, use a strict IQ score cutoff of 70. Today’s decision will impact Alabama death penalty cases because, by adopting such a cutoff, Alabama courts have failed to “recognize, as does the medical community, that the IQ test is imprecise.” Since “[a] State that ignores the inherent imprecision of these tests risks executing a person who suffers from intellectual disability,” Alabama’s use of a cutoff is unconstitutional.

“The death penalty is the gravest sentence our society may impose,” the Court reasoned. “Persons facing that most severe sanction must have a fair opportunity to show that the Constitution prohibits their execution. Florida’s law contravenes our nation’s commitment to dignity and its duty to teach human decency as the mark of a civilized world.”