By MARK SHERMAN
Associated Press

WASHINGTON - The U.S. Supreme Court appears divided over whether the drugs commonly injected to execute prisoners risk causing excruciating pain in violation of the U.S. Constitution's prohibition of "cruel and unusual punishment."

Several justices indicated a willingness to preserve the three-drug cocktail that is authorized by three dozen states that allow executions. Such a decision would allow lethal injections, on hold since late September, to resume quickly.

Hon. Antonin Scalia said states have been careful to adopt procedures that do not seek to inflict pain and should not be barred from carrying out executions even if prison officials sometimes make mistakes in administering drugs.

"There is no painless requirement" in the Constitution, Scalia said. Chief Justice Hon. John Roberts and Hon. Samuel Alito also indicated their support for the states' procedures.

Other members of the court, who have raised questions about lethal injection in the past, said they are bothered by the procedures used in Kentucky and elsewhere in which three drugs are administered in succession to knock out, paralyze and kill prisoners.

The argument against the three-drug protocol is that if the initial anesthetic does not take hold, a third drug that stops the heart can cause excruciating pain. The second drug, meanwhile, paralyzes the prisoner, rendering him unable to express his discomfort.

"I'm terribly troubled by the fact that the second drug is what seems to cause all the risk of excruciating pain, and seems to be almost totally unnecessary," said Hon. John Paul Stevens.

Hon. Anthony Kennedy, who often plays a decisive role on the closely divided court, gave little indication of his views.

The case before the court comes from Kentucky, in which two death-row inmates are not asking to be spared execution or death by injection. Instead, they want the court to order a switch to a single drug, a barbiturate that causes no pain and can be given in a large enough dose to cause death.

At the very least, they are asking for tighter controls on the three-drug process to ensure that the anesthetic is given properly. A decision should come by late June.

Hon. Stephen Breyer seemed to capture the discomfort of the court, which has upheld the constitutionality of capital punishment.

"There is a risk of human error generally where you're talking about the death penalty, and this may be one extra problem," Breyer said. "But the question here is, can we say that there is a more serious problem here than with other execution methods?"

Donald Verrilli, a Washington lawyer who is a veteran of capital cases, offered the court examples of executions in California and North Carolina in which inmates appeared to suffer pain as they were being put to death.

He said the best way to avoid repetition was to switch to a single drug, as veterinarians commonly use in ending animals' lives.

Lawyer Roy Englert said on behalf of Kentucky that the one-drug method has never been used in executions. The Bush administration also took Kentucky's side.

The state's lone execution by lethal injection did not present any obvious problems, both sides agreed.

The court may decide that the Kentucky case is not the right one to settle the constitutionality of the three-drug procedure.

Hon. David Souter urged his colleagues to take the time necessary to issue a definitive decision about the three-drug method in this case, even if it means sending the case back to Kentucky for more study.

Scalia said such a move would mean "a national cessation of executions" that could last for years. "You wouldn't want that to happen," he said.

Recent executions in Florida and Ohio took much longer than usual, with strong indications that the prisoners suffered severe pain in the process.

Natasha Metzler contributed to this report.