Updated

The number of death sentences handed out in the United States dropped in 2006 to the lowest level since capital punishment was reinstated 30 years ago, reflecting what some experts say is a growing fear that the criminal justice system will make a tragic and irreversible mistake.

Executions fell, too, to the fewest in a decade.

"The death penalty is on the defensive," said Richard Dieter, director of the Death Penalty Information Center, a Washington organization that looks at problems with the capital punishment system.

Death sentences fell in 2006 to 114 or fewer, according to an estimate from the group. That is down from 128 in 2005, and even lower than the 137 sentences the year after the U.S. Supreme Court reinstated the death penalty in 1976. It is also down sharply from the high of 317 in 1996.

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A total of 53 executions were carried out in 2006, down from 60 in 2005. Executions over the past three decades peaked at 98 in 1999.

Among the many causes given by prosecutors, lawyers and death penalty critics: the passage of more state laws that allow juries to impose life without parole; an overall drop in violent crime; and a reluctance among some authorities to pursue the death penalty because of the high costs of prosecuting a capital case.

But above all, many said, is the possibility of a mistake, made dramatically clear in recent years. Since the death penalty was reinstated, 123 people have been freed from death row after significant questions were raised about their convictions — 14 of them through DNA testing, according to the Death Penalty Information Center.

"The fact is they've gotten a lot of the wrong guys," said Deborah Fleischaker, director of the American Bar Association's Death Penalty Moratorium Implementation Project. "There's no question that has, in the public, created a lot of doubt about how the death penalty is working."

The turn away from the ultimate punishment also reflects a changing sentiment among juries and prosecutors, too, said Arthur Green, district attorney in Bessemer County, Alabama, outside of Birmingham. He said he considers the risk of executing an innocent person in deciding whether to pursue the death penalty.

"That's one reason I don't do it, except in very, very rare circumstances — one, that I'm convinced he or she did it, and number two, it's a horrible crime," Green said. He has sought and won two capital cases since becoming district attorney in 2001.

Thirty-seven of the 38 U.S. states that have the death penalty on their books now also allow for life without parole. Texas enacted such a law in 2005. Life-without-parole laws give another option to jurors who fear that the death penalty is the only way to keep a killer from getting out on the streets again.

The death penalty has also received more scrutiny from lawmakers around the U.S. and the courts.

Illinois is in the seventh year of its moratorium on executions, and executions are effectively halted in New York because of a 2004 court ruling.

Also, questions about whether lethal injection is inhumane have put executions on hold in nine states — Arkansas, California, Delaware, Florida, Maryland, Missouri, New Jersey, Ohio and South Dakota — and in the federal system.

This week in New Jersey, a special commission recommended that the state become the first to abolish the death penalty legislatively since 1976, citing "increasing evidence that the death penalty is inconsistent with evolving standards of decency."

Backers of capital punishment say support for the death penalty remains strong, despite the drop-off in death sentences.

"It's a refinement. I don't think it's an abandonment of the death penalty, but a recognition that the death penalty should be reserved for the worst of the worst," said Joshua Marquis, district attorney in Clatsop County, Oregon, and a vice president of the National District Attorneys Association.

"From prosecutors, there's a more discriminating attitude about which cases to bring," he said. "Juries have been much more picky about allocating the death penalty and I think that's an appropriate thing to do."

A Gallup poll in May found that two-thirds of Americans 18 and older support the death penalty. But when asked which is the better penalty for murder, roughly half said life without parole and about half said the death penalty.

For more news on the death penalty, click here.