The U.S. Supreme Court's rejection yesterday of a challenge to how lethal injections are conducted clears the way for executions to resume in Virginia and across the country.

But opponents of the procedure in Virginia and elsewhere say the high court's 7-2 decision, which involved seven different opinions, also leaves open the way for more challenges.

Virginia Gov. Timothy M. Kaine, who delayed one execution this month and promised to halt others until the court ruled, said yesterday that lethal injections can resume in Virginia.

"The governor will continue to review any clemency requests on a case-by-case basis," said Kaine spokesman Gordon Hickey.

According to authorities, killers Kevin Green, Percy Walton and Edward Bell are scheduled to be executed May 27, June 10 and July 24, respectively.

There had been a de facto moratorium on lethal injections nationwide since September, when the justices agreed to hear the constitutional challenge to lethal injection from two Kentucky inmates.

At least 29 other states -- including Virginia -- use the same combination of drugs as Kentucky: The first induces unconsciousness, the second paralyzes, and the third stops the heart.

Critics claim that if the procedure is not performed properly, an inmate can be conscious, aware he is dying and in great pain but be immobilized and unable to convey it. Kentucky's procedures had been upheld in lower courts, as have Virginia's.

Among other things, the Kentucky inmates said an execution from a massive dose of the first drug, a barbiturate, was preferable to the three-drug mix.

Virginia has executed 98 killers -- 70 by injection -- since the justices allowed executions to resume in 1976. Condemned inmates have been able to choose between injection or electrocution here since 1995.

The last Virginia execution was that of John Yancey Schmitt on Nov. 9, 2006. On April 1, Kaine delayed the April 8 execution of Bell until July 24.

Kaine, though personally opposed to the death penalty, has said he believes the way Virginia conducts lethal injections is constitutional.

Nevertheless, he promised to delay executions until the justices ruled, to prevent the need for 11th-hour stays such as the one the U.S. Supreme Court granted Christopher Scott Emmett in October hours before he was to die.

Virginia Attorney General Bob McDonnell, who was critical of Kaine's actions on April 1, said in a statement yesterday, "Now that the court has ruled, the governor has rightly lifted his moratorium on executions in Virginia."

Chief Justice John G. Roberts Jr. wrote in his opinion that the Kentucky inmates "have not carried their burden" of showing that the risk of pain from the improper administration of a "concededly humane lethal injection protocol" constituted cruel and unusual punishment.

Two other justices joined Roberts' opinion. In all, seven justices wrote opinions. Only two of them, Ruth Bader Ginsburg and David H. Souter, dissented.

The ruling does not put to rest issues over lethal injection, Justice John Paul Stevens said. He wrote: "When we [agreed to hear] this case, I assumed that our decision would bring the debate about lethal injection as a method of execution to a close.

"It now seems clear that it will not," he said, even though he sided with the majority.

Stevens wrote that the court and legislatures should re-examine the question of whether it is time to end the death penalty, a move his opinion makes clear he now favors.

Richard Dieter of the Death Penalty Information Center said yesterday's holding does not prevent challenges to lethal-injection procedures in other states.

Emmett's case, set to be argued May 14 in the 4th U.S. Circuit Court of Appeals, could have an impact on Virginia's scheduled executions.

Rob Lee, executive director of the Virginia Capital Representation Resource Center, said yesterday's ruling sets the standard for proving an 8th Amendment violation by showing there is a "substantial risk" of serious harm.

In Emmett's case, a federal judge held that to prove his claim, Emmett had to show the state put procedures in place with "deliberate indifference" to the risk of harm -- a much higher standard than "substantial risk."

Lee said that, in Emmett's case, "it's clear the correct standard wasn't applied" when Virginia's lethal-injection procedures were considered by the lower court. Lee said the appeals court may decide to resolve the differing standards, which could delay other executions.

Carl Tobias, a professor at the University of Richmond's School of Law, said there likely will be more litigation over lethal injection. But, he said, "I think the splintering makes it very difficult to tell what will happen."

Contact Frank Green at (804) 649-6340 or fgreen@timesdispatch.com.