Clarence Hill's lawyer said that he had been strapped to a gurney with IV lines running into his arms Tuesday night when Justice Anthony M. Kennedy issued a temporary stay.
The full court made the stay permanent, and ordered both sides to file more arguments.
Hill argues that the three chemicals used in Florida's lethal injection method of execution cause pain, making his execution cruel and unusual punishment. His lawyer also contends that Hill is mentally retarded.
He is on death row for the Oct. 19, 1982, slaying of Pensacola police Officer Stephen Taylor, 26, and the wounding of his partner, Larry Bailly, when they responded to a silent alarm of a bank robbery.
Hill's case allows the court to revisit a 2004 ruling in an Alabama death case, in which justices said that David Larry Nelson could pursue a last-ditch claim that his death by lethal injection would be unconstitutionally cruel because of his damaged veins.
While Hill does not have damaged veins, his appeal cites medical studies about the drug cocktail used by Florida and other states.
"The question now is whether this result impacts other death penalty cases, says CBSNews.com Legal Analyst Andrew Cohen "Will the Supreme Court allow many other legal injection executions to go forward while it decides whether the mix of chemicals is cruel and unusual punishment?"
An appeals court had said Hill brought the challenge too late.
His lawyer, D. Todd Doss, told justices that there is a risk that he will not be properly anesthetized at the time of his death.
"The Court has become more and more curious about whether lethal injections are humane enough to comply with the Eighth Amendment and its prohibition against cruel and unusual punishment," says Cohen. "So it isn't a terrible shock that the Justices would take this sort of a case. And you can bet that attorneys all over the country will be making similar claims on behalf of their death row inmates."