WASHINGTON (AP) — The U.S. Supreme Court on Tuesday freed Alabama to try again to execute a convicted killer who has been on death row for 30 years and had seven execution dates postponed.

The justices turned down an appeal from inmate Tommy Arthur. The decision came after the court in November issued a last-minute stay to block Arthur's execution as he sat in a holding cell outside the state's lethal injection chamber.

Chief Justice John Roberts said Arthur's appeal "does not merit the court's review."

Justices Sonia Sotomayor and Stephen Breyer said they would have heard the appeal, which centered on a requirement that condemned inmates challenging their method of execution name a feasible alternate method that is also allowed by state law. Arthur argued to the high court that it is virtually impossible to challenge Alabama's lethal injection procedures after a federal judge said inmates must identify an alternate source of execution drugs and a detailed plan for carrying out the execution.

The effect of Tuesday's action is to allow the state to try again to put Arthur to death by lethal injection. It is anticipated that the state attorney general's office will seek an eighth execution date for him.

Arthur's attorney Suhana Han declined to comment on the court's decision.

Arthur was convicted of killing Troy Wicker in 1982 as the man slept inside his Muscle Shoals home. Investigators said Arthur was having an affair with Wicker's wife and she paid him $10,000 to kill her husband. Arthur was in a prison work-release program in Decatur at the time of the slaying after being convicted of the 1977 murder of his sister-in-law in Marion County.

Arthur has maintained his innocence.

Sotomayor said in an 18-page opinion that Arthur had presented considerable evidence that Alabama's lethal injection procedures "will result in intolerable and needless agony" and had suggested a firing squad as an alternative.

She noted that the court has twice said in death-penalty cases that it has never ruled that a state's execution method violated the Constitution's ban on cruel and unusual punishments.

"We should not be proud of this history. Nor should we rely on it to excuse our current inaction," Sotomayor wrote, joined by Breyer.

The decision in the Arthur case was handed down as the Supreme Court also rejected an attempt by Arkansas inmates to stop their executions over claims that their deaths would be "intolerably painful."

The nine inmates asked the justices to review an Arkansas Supreme Court decision upholding a law that keeps the source of the lethal injection drugs secret. Arkansas has not executed an inmate since 2005 because of legal challenges and the difficulty of obtaining execution drugs. A batch of one of Arkansas' execution drugs expired New Year's Day and an agency spokesman said Tuesday that it had not acquired additional doses of potassium chloride.