The Supreme Court (search), which two years ago abolished executions for the mentally retarded, said Monday it will now consider ending the execution of killers who were under 18 when they committed their crimes.

The court said it will reopen the question of whether executing very young killers violates the Constitution's ban on "cruel and unusual punishment." Currently, states that allow the death penalty may impose it on killers who were 16 or 17 at the time of their crimes.

The case, which will probably be deourt's reexamination of who belongs on death row and how the death penalty is carried out. The court's calendar for the current term is apparently full, with oral arguments scheduled through April.

The court agreed to hear the case of a Missouri man who was 17 when he robbed a woman, wrapped her head in duct tape and threw her off a railroad bridge in 1993. The state Supreme Court declared it unconstitutional to send people to their deaths for killings committed when they were younger than 18.

The 4-3 decision by the Missouri Supreme Court overturned the death sentence of Christopher Simmons (search), and sentenced him to life in prison instead.

Four Supreme Court justices are on record opposing the execution of very young killers, but the court has nonetheless stayed on the sidelines of a national and international debate about the practice. The court has turned aside several recent appeals brought by death row inmates challenging their executions for juvenile crimes. The court did not comment in agreeing to hear the issue now, in an appeal brought by state officials.

In 2003, the four-member liberal wing of the court 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 2002 ruling 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.

Also like the retardation question, this one will involve an examination of whether the country has changed its mind about what kind of punishment is appropriate.

The court relied heavily on the actions of state legislatures in deciding to ban executions of the retarded. On that issue, the court said the large number of states that had acted on their own to ban such executions showed that the nation no longer supported the practice.

The court majority said, in effect, that times change and that the constitutionality of such executions changes with them. The 6-3 ruling drew fierce dissents from the court's three most conservative members, who view the Constitution as a more rigid document.

Shortly after that ruling, Stevens predicted that juvenile killers would be the next major death penalty question before the court.

The issue has been there before. The high court upheld juvenile executions in 1989, and will now consider reversing that ruling.

Only the United States and a handful of other countries allow execution of juvenile killers, and death penalty opponents argue that such executions violate not only the Constitution but an international treaty signed by the United States.

Currently, 17 states that allow the death penalty for other people prohibit it for those who were under 18 when they committed their crimes. The federal government also prohibits the practice for juveniles prosecuted in federal court.

According to the Death Penalty Information Center (search), there are now 82 inmates on death row nationwide for crimes committed when they were under 18. States have put to death 22 such inmates in recent years.

The case is Roper v. Simmons, 03-633.