The Supreme Court for the first time on Monday put a strict constitutional limit on prison terms, ruling it is cruel and unusual punishment to send a young criminal to prison for life with no chance for parole for a crime that does not involve murder.

The ruling is the second in recent years to greatly expand the constitutional protections for juveniles. And once again, the justices in the majority said they agreed with international critics who say the United States is out of step when it comes to treatment for the young.

There has been a "global consensus" among all nations but the United States that juvenile criminals should not be locked up for life with no chance to rehabilitate themselves, said Justice Anthony M. Kennedy.

"From a moral standpoint, it would be misguided to equate the failings of a minor with those of an adult," he wrote, quoting his 2005 opinion that rejected the death penalty for underage murderers.

That ruling spared several dozen young murderers from possible execution.

Monday's ruling gives new hope - although no guarantee of release - to at least 129 prisoners nationwide who were given life terms for crimes such as robbery or assault that took place before they were 18.

California has 249 juveniles sentenced to life without possibility of parole, but only two that did not involve a murder, according to a preliminary review by state corrections officials.

Conservatives in Congress have sharply criticized Kennedy for citing international legal norms. They said the interpretation of the Constitution should be unaffected by foreign views.

Undaunted, Kennedy said again on Monday that the "judgment of the world's nations" deserved to be considered when U.S. judges decided what was cruel and unusual punishment. These international norms are not "binding or controlling," he said, but they can "provide respected and significant confirmation for our own conclusions."

The ruling came in the case of Terrance Graham, who at 16 pleaded guilty to taking part in the armed robbery of a barbecue restaurant in Florida. A year later, he was arrested for a home-invasion robbery.

The judge, acting on a Florida law that allowed juveniles to be treated as adults, gave him life in prison with no chance for parole.

Justices John Paul Stevens, Ruth Bader Ginsburg, Stephen G. Breyer and Sonia Sotomayor agreed with Kennedy that such a life term for a young offender is always unconstitutional. Young criminals may be locked up for years, but they deserve "some realistic opportunity" to seek their release, they said.

This ruling, Graham vs. Florida, struck down the laws in California and 36 other states that permit such life sentences with no parole.

Chief Justice John G. Roberts Jr. agreed that Graham's sentence was unconstitutionally cruel. It was "grossly disproportionate" to the crime, he said, since burglary and robbery usually result in about five years behind bars. But he did not agree that such prison terms were unconstitutional in all cases. He cited the case of a 17-year-old who raped an 8-year-old girl and buried her alive, and another involving a group of juveniles who raped a woman in front of her young son.

The dissenters - Justices Clarence Thomas, Antonin Scalia and Samuel A. Alito Jr. - said the court should not impose "its own independent moral views" that these life prison terms are cruel and unusual punishment. Thomas said the justices should let states set the proper prison terms for criminals.

A Washington lawyer representing the National District Attorneys Assn. denounced the ruling. The court's decision "creates a whole new category of constitutionally protected criminals, essentially a 'get out of jail free' card for underage criminals repeatedly convicted of adult heinous violent crimes," said attorney Gene Schaerr.

But others saw it as a step forward.

"None of us are the same people we were as teenagers," said Marsha Levick, deputy director of the Juvenile Law Center in Philadelphia. "When it comes to sentencing youth, we should not make irrevocable decisions."

Human Rights Watch says the United States has 2,574 inmates serving life terms for crimes they committed before age 18. The vast majority of young criminals who get life terms were involved in homicides.

Of the 129 prisoners directly affected by Monday's ruling, 77 are in Florida. In addition to California, the other states with at least a few such prisoners are Delaware, Iowa, Louisiana, Mississippi, Nebraska, Nevada, Oklahoma, South Carolina and Virginia.