WASHINGTON — With an inmate spared execution yesterday in Virginia, America is headed for the fewest executions in a year since the mid-1990s because of concerns over lethal injections and the Supreme Court’s pending review of the issue.

The 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.

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 September 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 David Dow, who runs the Texas Innocence Network out of the University of Houston Law Center.

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. “This is a last-ditch effort by fervent death penalty opponents who have lost every other battle,” Mr. Marquis said. “They’re literally at the death house door.”