NASHVILLE, Tenn. (AP) — A Tennessee death row inmate is asking a federal judge to postpone his December execution, saying that he is intellectually disabled.

The U.S. Supreme Court has ruled that executing an intellectually disabled person violates the Eighth Amendment’s prohibition on cruel and unusual punishment. In a court filing on Monday, attorneys for Pervis Payne argue that in Tennessee, however, there is no procedure to allow Payne to bring his claim of intellectual disability before the courts.

Tennessee has its own law forbidding the execution of the intellectually disabled, but that law does not contain a mechanism for people to reopen their cases if they were sentenced before the law went into effect, according to the court filing. State Rep. G. A. Hardaway has said he intends to file a bill to address the problem, but the next legislative session does not begin until January. Payne's execution date is Dec. 3. In his petition to the federal court in Nashville, Payne asks the judge to postpone his execution until after Tennessee's law is amended and a court examines his intellectual disability claim.

Payne was sentenced to death in a Memphis court for the 1987 stabbing deaths of Charisse Christopher and her 2-year-old daughter, Lacie Jo. Christopher’s son, Nicholas, who was 3 at the time, was also stabbed but survived. Payne, who is Black, has always maintained his innocence. He told police he was at Christopher’s apartment building to meet his girlfriend when heard the victims, who were white, and tried to help them. Then he panicked when he saw a white policeman and ran away.

In a separate petition filed in state court, Payne is asking a judge to order that DNA evidence in his case be tested. The Memphis district attorney opposes the testing and a ruling is expected Wednesday.

The Monday filing claims the evidence of Payne's intellectual disability is “unassailable.” In addition to IQ testing, attorneys spoke to people who knew Payne as a young man and said Payne could barely read or write, could not follow complex directions, couldn't use a ruler, count money or iron clothes.

A spokesperson for the Tennessee Attorney General's Office said they have no comment on Payne's petition.

In a news release from Payne's attorneys, Katie Powers, a past president of the Tennessee Disability Coalition, said the U.S. Supreme Court banned the execution of people with intellectual disability because it “recognized that people with intellectual disability present ‘a special risk of wrongful execution’ because they have trouble assisting their attorneys and make poor witnesses on their own behalf. This is precisely what happened to Pervis Payne.”

The U.S. Supreme Court declined to hear a similar case out of Tennessee in July. In that case, lawyers for David Keen said tests from 2008 and 2010 prove Keen’s intellectual disability, but there is no procedural mechanism to reopen Keen’s case and present the evidence to a court. Attorneys for the state opposed Keen’s petition, arguing, in part, that Keen was not intellectually disabled.