Hours after staying the execution of a Florida inmate who was already strapped to a gurney, the Supreme Court said Wednesday it would hear his arguments that the drug cocktail used in lethal injections can cause excruciating pain.

Lethal injections are used in most states that have capital punishment, and there's been a growing dispute over the way they are carried out.

The Supreme Court has never found a specific form of execution to be cruel and unusual punishment, and the latest case from Florida does not give court members that opportunity. The justices could, however, spell out what options are available to inmates with last-minute challenges to the way they will be put to death.

Florida inmate Clarence Hill, who filed the appeal, had been strapped to a gurney with intravenous lines running into his arms Tuesday night when he won a temporary Supreme Court stay, Hill's lawyer said. The stay was signed by Justice Anthony M. Kennedy.

The full court announced Wednesday that the stay would be permanent until justices decide whether an appeals court was wrong to prevent Hill from challenging the lethal injection method.

The argument is expected April 26, with a ruling before July.

"What a fantastic day. What a fantastic day," said Hill's attorney D. Todd Doss, who relayed the news to his client. "He was happy we get to go and present this to the U.S. Supreme Court."

Hill is on death row for killing a Pensacola, Fla., police officer after a bank robbery in 1982.

A Florida Department of Corrections spokeswoman said Hill would be moved off death watch, a cell block adjacent to the execution chamber, and back to death row.

Hill argues that the doses of three chemicals used in Florida executions — sodium pentothal, pancuronium bromide and potassium chloride — can cause pain. The first drug is a pain killer. The second one paralyzes the inmate and the third causes a fatal heart attack.

The final drug, potassium chloride, "burns intensely as it courses through the veins toward the heart," Doss wrote in the appeal. He said there is "a foreseeable risk of the gratuitous and unnecessary infliction of pain."

Hill's case allows the court to revisit a 2004 ruling in an Alabama death case, in which justices said 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 cocktail of drugs used by Florida and other states.

"The court may be willing to broaden what can be considered as a civil rights claim," said Richard Dieter, executive director of the anti-capital punishment Death Penalty Information Center.

Dieter predicted that inmates facing executions in coming months will requests delays, based on the Hill case.

Justice Sandra Day O'Connor, who is retiring, wrote the 2004 decision, which said that although Nelson had exhausted his traditional appeals, he should not have been barred from pursuing the issue that came up in the final days before the scheduled execution.

O'Connor said in the unanimous 2004 ruling that the court was not going to "open the floodgates to all manner of method-of-execution challenges."

If appeals court Judge Samuel Alito is confirmed, as expected, to replace O'Connor, he will hear arguments and help decide the case.

The case is Hill v. Florida, 05-8794.