The case involves an Alabama man who challenged his death sentence after a murder conviction because of his varying results in a series of I.Q. tests.

The U.S. Supreme Court heard arguments in Alabama’s appeal to reinstate the death sentence for Joseph Clifton Smith. A lower court found Smith intellectually disabled based on multiple IQ scores and evidence of adaptive deficits,

Seth P. Waxman, Smith’s lawyer, told the justices that the lower federal courts in his client’s case correctly applied Alabama law, which allows judges to consider “evidence of intellectual functioning other than IQ test scores at least where a court, considering expert testimony, concludes that those scores alone don’t decide the issue.”

The Florida Supreme Court on Thursday rejected two challenges to a 2023 law that allows judges to impose death sentences without unanimous jury recommendations.