States must not rigidly apply intelligence test scores in borderline cases of mental disability to determine whether an inmate on death row is eligible to be executed, the Supreme Court ruled Tuesday.
In a 5-4 ruling, the justices said that Florida and a handful of other states cannot rely solely on an IQ score above 70 to bar an inmate from claiming mental disability since IQ tests have a margin of error, the Associated Press reported.
Inmates whose scores fall within the margin must be allowed to present other evidence of mental disability, Justice Anthony Kennedy said.
"The death penalty is the gravest sentence our society may impose," Kennedy wrote in the ruling.
"Persons facing that most severe sanction must have a fair opportunity to show that the Constitution prohibits their execution."
Although a high score of 75 can be considered intellectually disabled due to the test's margin of error, a score of 70 is widely accepted as a marker of mental disability, medical professionals said.
In 2002, the Supreme Court barred states from executing prisoners who have a mental disability, but left to the states the determination of who is mentally disabled.
Kennedy said states must give inmates the chance to present evidence of mental disability in borderline cases, according to the AP.
"The states are laboratories for experimentation, but those experiments may not deny the basic dignity the Constitution protects," Kennedy said in an opinion that was joined by the court's four more liberal justices.
Since the court has no evidence that relying on test scores just above 70 is unreasonable, it should not be held unconstitutional, Justice Samuel Alito said in dissent for the four justices to the right of Kennedy.
"Tuesday's decision came in the case of 68-year-old Freddie Lee Hall. Lawyers for Hall said there is ample evidence to show that he is mentally disabled, even though most of his multiple IQ tests have yielded scores topping 70," the AP reported. "Hall has been on death row for more than 35 years since being convicted of murdering a pregnant 21-year-old woman in 1978."
