WASHINGTON – The Supreme Court indicated Monday that states should look beyond an intelligence test score in borderline cases of mental disability to determine whether a death row inmate is eligible to be executed.

Twelve years after the Supreme Court barred execution of the mentally disabled, the justices heard arguments about how states evaluate claims of mental disability that, if substantiated, protect inmates from being put to death.

Five justices, enough to form a majority, pointed repeatedly to the margin of error inherent in IQ and other standardized tests. They voiced skepticism about the practice in Florida and certain other states of barring an inmate from claiming mental disability when his IQ score is just above 70.

"Your rule prevents us from getting a better understanding of whether the IQ score is accurate or not," Justice Anthony Kennedy told Florida Solicitor General Allen Winsor. Kennedy and the four liberal justices objected to Winsor's argument that there is no wiggle room when an IQ score tops 70.

That score is widely accepted as a marker of mental disability, but medical professionals say people who score as high as 75 can be considered intellectually disabled because of the test's margin of error. In any case, there is a consensus that the test score should be just one factor in determining mental disability.

Lawyers for inmate Freddie Lee Hall said there is ample evidence to show that he is mentally disabled, even though he topped 70 on most of his IQ tests. Hall has been on death row for more than 35 years since being convicted of murdering a pregnant 21-year-old woman in 1978.

Winsor said abandoning the 70-point IQ cutoff could double the number of death row inmates who claim they are mentally disabled.

Justice Elena Kagan said Winsor might be right about the rise in the number of claims. "But some of them may be mentally retarded," Kagan said.

Justice Antonin Scalia pointed to the several steps Hall took to abduct and kill the woman, and later a sheriff's deputy, as indications that Hall seemed to have sufficient mental capability.

A decision in the case is expected by late June.