WASHINGTON - The Supreme Court’s decision to review the constitutionality of lethal injection procedures has slowed the annual number of executions to the lowest level in a decade amid renewed concerns about whether it’s too cruel.

On Wednesday, the high court blocked Virginia’s plans to kill Christopher Scott Emmett, 36, hours before he was to die by lethal injection. Courts in Nevada and Texas this week also postponed executions scheduled before the end of 2007, making it one of the quietest years so far for executions since the mid-1990s.

“Some courts are being prudent by waiting to see how the Supreme Court will go,” said Lisa McCalmont, a consultant to the death penalty clinic at the University of California at Berkeley law school.

Fewer than 50 executions will take place this year, even if several states pushing ahead with lethal injections defeat legal efforts to stop them. The last time executions numbered fewer than 50 was in 1996, when there were 45.

Since executions resumed in this country in 1977 after a Supreme Court-ordered halt, 1,099 inmates have died in state and federal execution chambers. The highest annual total was 98 in 1999, according to the Death Penalty Information Center, which opposes capital punishment.

So far this year, 42 people have been executed. Texas, where 26 prisoners have been executed this year, plans no more executions in 2007 after federal and state judges stopped four death sentences from being carried out.

Executions also have been delayed in Alabama, Arizona, Arkansas and Oklahoma since the court announced Sept. 25 it would hear a challenge to Kentucky’s lethal injection method. Courts in California, Delaware, Missouri, North Carolina and Tennessee have previously cited problems with lethal injections procedures in stopping executions.

The last person executed in this country was Michael Richard, 49, who died by lethal injection in Texas the same day the Supreme Court agreed to consider the constitutionality of lethal injection procedures in Kentucky. A Texas state judge refused that day to accept an appeal from Richard’s lawyers, saying it had arrived after office hours.

Kentucky’s method of lethal injection executions is similar to procedures in three dozen other states. The court will consider whether the mix of three drugs used to sedate and kill prisoners has the potential to cause pain severe enough to violate the constitutional ban on cruel and unusual punishment.

“The U.S. is clearly in what amounts to a de-facto death penalty moratorium,” said Allen Bridgers’ attorney David Dow, who runs the Texas Innocence Network out of the University of Houston Law Center. Bridgers’ execution date has been delayed in Texas three times.

Josh Marquis, the district attorney in Clatsop County, Oregon, and a death penalty supporter, said executions should continue even while the Supreme Court looks at lethal injection.

Marquis distinguished the lethal injection issue from court reviews that led to banning execution of the mentally retarded and people younger than 18 when they committed their crime. “The court’s response is not going to be ban all lethal injections. At most, it’s going to be reformulate the protocol,” Marquis said.

The reprieves for the dozen or so men whose dates to die had been set are likely to be only temporary. Even the lawyers for the Kentucky inmates concede that there are alternative drugs and procedures available that lessen the risk of pain.

Justice Antonin Scalia also has suggested that people are reading too much into the court’s decision to take up the Kentucky case. Scalia said Tuesday night he would have allowed Arkansas to proceed with the execution of Jack Jones.

The 8th U.S. Circuit Court of Appeals had earlier put off Jones’ execution because of the high court review. That decision “was based on the mistaken premise” that the high court wants state and federal judges to intervene every time a defendant raises a court challenge to lethal injection, Scalia said in a statement accompanying the Supreme Court’s order that kept the appeals court ruling in place.

State officials in Florida, Georgia and Mississippi are continuing with plans to carry out death sentences despite the high court’s review.

Georgia has an execution scheduled for Friday and the Supreme Court again could be asked to step in on behalf of Jack Alderman, sentenced to die in the 1974 killing of his 20-year-old wife, Barbara.

The state Supreme Court and pardons and paroles board have so far turned down Alderman’s pleas to be spared. Another Georgian, Curtis Osborne, also is scheduled to die this month.

In Florida and Mississippi, state high courts are considering pleas for a delay from condemned inmates.

Lawyers for Mississippi are arguing that there is no reason to wait for the Supreme Court lethal injection ruling. Earl Wesley Berry has an Oct. 30 execution date for the 1987 killing of Mary Bounds, who was beaten to death after leaving her weekly church choir practice.

In Florida, Mark Dean Schwab, 38, is scheduled to die Nov. 15 for the rape and murder of 11-year-old Junny Rios-Martinez. Executions had been suspended since December after it took twice as long as usual — 34 minutes — for a convicted killer to die. Gov. Gov. Charlie Crist lifted the moratorium in July by signing Schwab’s death warrant.