The Supreme Court has refused to halt the execution of a Georgia man whose lawyers say he is ineligible to be executed because he is intellectually disabled. Warren Lee Hill's lawyers argue he shouldn't be executed because he is intellectually disabled.

The justices on Tuesday turned away a last-minute plea from Warren Lee Hill. He is scheduled to be executed at 7 p.m. at the state prison in Jackson, Georgia.

Different courts have intervened with temporary reprieves at the last minute on three previous occasions. Justices Stephen Breyer and Sonia Sotomayor said they would have granted Hill another reprieve.

State and federal courts had already rejected his filings this time around, and the State Board of Pardons and Paroles —the only entity authorized to commute his sentence to life in prison — denied him clemency Tuesday. Hill has filings pending before the U.S. Supreme Court, which is now the only potential barrier between him and a lethal injection of the drug pentobarbital.

"The clemency board missed an opportunity to right a grave wrong," Brian Kammer, a lawyer for Hill, said in an emailed statement Tuesday. "It is now up to the U.S. Supreme Court to ensure that an unconstitutional execution of a man with lifelong intellectual disability is prevented."

Hill was sentenced to serve life in prison for the 1986 killing of his 18-year-old girlfriend, who was shot 11 times. While serving that sentence, he beat a fellow inmate, Joseph Handspike, to death using a nail-studded board. A jury in 1991 convicted Hill of murder and sentenced him to death.