Updated

The Supreme Court was urged Wednesday to keep mentally retarded killers off state death rows by declaring those executions unconstitutionally cruel and unusual punishment.

The case turns on whether the public's attitudes about those executions have changed since 1989, when the court upheld them by a 5-4 vote. Since then, the number of states banning executions of the mentally retarded has increased from two to 18.

Justices are reviewing the death sentence of Daryl Renard Atkins, convicted of carjacking and killing an airman in Virginia to get money for beer. One test showed Atkins had an IQ of 59. People who test 70 or below generally are considered mentally retarded.

If the court overturns his sentence, other death row inmates with mental retardation claims could pursue appeals.

The question that most interested the court during Wednesday arguments was whether there is now a national consensus that those executions are cruel.

"We have to be very careful about finding a new consensus. We can't go back," Justice Antonin Scalia said.

James Ellis, representing Atkins, said there is a growing concern that mentally retarded defendants might be more likely to face the death penalty.

Virginia's Legislature debated a ban, but decided to await the outcome of this case.

Pamela A. Rumpz, an assistant attorney general in Virginia, said many of the state bans are relatively new.

"That's a blip in the radar screen of public opinion," she said. "It may change in two years. It may change in three years."

Steven Hawkins, executive director of the National Coalition to Abolish the Death Penalty, said up to one-fourth of death row inmates may have mental retardation claims. There are more than 3,700 people on death row, some in states with bans.

"This is one of the most important death penalty cases to come to the Supreme Court in the last quarter century," Hawkins said.

Kent Scheidegger, legal director for the pro-death penalty Criminal Justice Legal Foundation, said the decision in the Atkins case, like the 1989 case, will likely be close.

Justices face many questions, he said. "How do you define retarded? Where do you draw the line? Who determines that?"

The victim in the case, 21-year-old Eric Nesbitt, was kidnapped in 1996 outside a convenience store and forced to withdraw money from an automatic teller machine. Atkins, then 18, and an accomplice were accused of taking Nesbitt to a deserted field and shooting him eight times. Nesbitt was stationed at Langley Air Force Base in Hampton, Va. He was robbed of $260.

President Bush has said he opposes executing the retarded.

"We should never execute anybody who is retarded," Bush said last June. "And our court system protects people who don't understand the nature of the crime they committed."

Texas is one of the states that does not have such a ban and the state has executed six retarded defendants since 1982, two of them while President Bush was governor, according to the Death Penalty Information Center. Prosecutors have disputed the IQ of some of those inmates.

The states that generally ban executions of the mentally retarded are Arizona, Arkansas, Colorado, Connecticut, Florida, Georgia, Indiana, Kansas, Kentucky, Maryland, Missouri, Nebraska, New Mexico, New York, North Carolina, South Dakota, Tennessee, and Washington.

The case is Atkins v. Virginia, 00-8452.