The Georgia Board of Pardons and Paroles voted to deny clemency to a death row inmate whose lawyer says is mentally disabled. The decision highlights the state’s strictest in the nation standard for proving mental disability.

Warren Lee Hill’s defense team argued his sentence should be commuted to life in prison without parole because both state and federal law prohibit states from executing the mentally retarded.

Hill was convicted in 1991 and sentenced to death for killing a fellow inmate. The state said the defense failed to prove beyond a reasonable doubt that Hill is mentally disabled.

Dr. Robert Latzman, of Georgia State University, says the state’s high standard of proof is problematic:

“This isn’t a blood test—it’s not that we can take blood and send it to the lab, and that the levels, here they are, and no matter what lab we send it to, the levels are going to be the same—because of that, the reliability in terms of a diagnosis is not 100%.”

Hill is schedule to die by lethal injection on Wednesday.

Tags: parker wallace, Warren Lee Hill, mentally retarded