The US Supreme Court questioned Monday whether a man deemed mentally handicapped by a federal court but not his home state should be executed without a new hearing assessing his intellectual disability.
In its 2002 decision Atkins v. Virginia, the high court forbade the execution of people with intellectual handicaps.
The court found that such an execution would amount to "cruel and unusual punishment," which is banned by the US Constitution`s Eighth Amendment.
But it left it up to individual states to determine what constitutes a mental disability.
The case heard Monday involves Kevan Brumfield, who was sentenced to death by a state court for killing a police officer in Baton Rouge, Louisiana in 1993.
Though the suspect`s mental capacity did come up at trial, the law did not at the time prohibit capital punishment for the mentally disabled.
After the Supreme Court`s 2002 ruling, Brumfield`s lawyers argued he should be spared death due to intellectual disability.
He appealed for a hearing and funding to conduct an intelligence assessment, but the Louisiana state court denied his request, saying Brumfield`s IQ was 75 and therefore he was not considered mentally disabled.
An IQ of lower than 70 is considered an intellectual disability, according to the Supreme Court`s 2002 decision.
But a US federal court later approved the intelligence assessment and concluded that Brumfield was in fact intellectually handicapped and therefore ineligible for execution.
The New Orleans Fifth Circuit Court of Appeals then ruled that the state`s original sentence should be upheld and that Brumfield should remain on death row.
Capital punishment sentences normally fall under the purvey of state law, and this case could determine whether federal courts can block a state`s death sentence if the punishment is considered "unreasonable."
"If the state court does not give adequate process by denying hearing and funding, you`ve been unreasonable and you`re not entitled to deference," said Brumfield lawyer Amir Ali.
"There was overwhelming evidence of impairment," another Brumfield attorney, Michael DeSanctis, argued before the nine-member bench.
Several justices asked whether a state may have a constitutional duty to offer fresh hearings to determine a defendant`s mental state, beyond what was revealed in a previous penalty-phase court hearing.
"Can a state make the final determination of mental incapacity, or lack thereof, based on a trial record that did not address the issue?" Justice Sonia Sotomayor asked.
Rob Dunham, director of the Death Penalty Information Center, agreed that Brumfield`s sentence was not in line with modern law.
"As death sentences and executions decline across the country, it is increasingly important that older cases such as Mr Brumfield`s be reviewed with the increased scrutiny demanded today," Dunham said.
In January, a convicted rapist and killer with an IQ of 67 was executed in Texas, after an appeal to the US Supreme Court to stay the death sentence was rejected.
An opinion in Brumfield`s case is expected by June.