Four Supreme Court justice want to ban the execution of very young killers, but they apparently cannot persuade their colleagues to reopen the debate.

The high court did not comment in turning down an appeal Monday from an Oklahoma death row inmate who was 17 when he helped burn a young couple alive in the trunk of their car.

Death penalty opponents had hoped the court would use the case to broaden an ongoing review of how the punishment is carried out and who belongs on death row.

The four-member liberal wing of the court knows the time is not right to revisit the question of whether 16- and 17-year-olds are as culpable as adult killers, and know they could be outvoted if the nine-member court took on the issue now, lawyers said.

"We're not there yet," said Steven Hawkins, executive director of the National Coalition to Abolish the Death Penalty. For now, he said, "There is not a fifth vote for change."

In October, the four issued an unusual statement calling it "shameful" to execute juvenile killers.

"The practice of executing such offenders is a relic of the past and is inconsistent with evolving standards of decency in a civilized society," Justice John Paul Stevens wrote then. He was joined by Justices David H. Souter, Ruth Bader Ginsburg and Stephen Breyer.

The rhetoric echoed the court's ruling last year that it is unconstitutional to execute the mentally retarded. In both instances, the constitutional question turns on the defendants' ability to understand their situation, and their level of culpability.

The court's 6-3 ruling excluding the retarded from the death penalty relied heavily on the premise that public attitudes had changed on the subject in the 13 years since the court had last upheld such executions.

In 1989, two states that used capital punishment outlawed the practice for retarded defendants. In 2002, 18 states prohibited it.

The shift was apparently enough to win the votes of swing voters Sandra Day O'Connor and Anthony M. Kennedy, who joined Stevens and the other three.

Death penalty opponents say they need the same kind of momentum among state legislatures on the question of young killers, and said the high court will get involved when more states outlaw the death penalty for those under 18.

Of the 38 states that allow the death penalty, 16 prohibit it for those who were under 18 when they committed their crimes. The federal government also bans capital punishment for juveniles prosecuted in federal court.

"This means we press on," said Stephen K. Harper of the Juvenile Death Penalty Initiative, a coalition of death penalty opponents and the American Bar Association that is working to change state laws. "We have to make a stronger a stronger argument with respect to changes in state legislatures ... so we can make a more convincing case to the Supreme Court."

Bills to eliminate the death penalty for those who were juveniles when they committed their crimes are already before legislators in Wyoming, Pennsylvania and Mississippi, with several more states expected to review the issue this year or next, lawyers said.

Dianne Clements of the victims' rights group Justice For All said capital punishment opponents may be overly optimistic.

"A majority of the Supreme Court ... is saying they still believe that capital murderers who commit their crimes when they are (under 18) are culpable," she said.

State juries tend to impose the death penalty for young killers only in the most horrific cases, she said.

The current case of Washington-area sniper suspect Lee Boyd Malvo, 17, may dampen any momentum to treat young killers more lightly, she added.

Whatever the high court's next move, it may come too late for Scott Allen Hain, the Oklahoma inmate in Monday's case. Hain is near the end of his appeals, and he could be put to death soon unless the court steps in.

"He's just going to miss out," said George Kendall of the NAACP Legal Defense and Educational Fund.