The United States Supreme Court determined juvenile offenders serving life sentences for homicides without parole should be granted the opportunity to “show their crime did not reflect irreparable corruption.”

The decision clarified a ruling issued in the 2012 case Miller v. Alabama, which prohibited life without parole sentences for juveniles who commit homicides. It established such sentences violate the Constitution’s Eighth Amendment prohibition on “cruel and unusual punishment.”

Henry Montgomery was 17 years-old when he killed a deputy sheriff in Louisiana. He is now 69 years-old and has spent most of his life in prison. After the decision in 2012, Montgomery sought what is known as “collateral relief” and maintained his sentence was illegal.

In the decision written by Justice Anthony Kennedy, the Supreme Court determined [PDF], because of prior decisions which found “children are constitutionally different from adults in their level of culpability,” offenders like Montgomery must be given the opportunity to show they have changed or matured. If they have changed, they must have “their hope for some years of life outside prison walls must be restored.”

According to the decision, states should extend parole eligibility to juvenile offenders, which would offer “someone like Montgomery, who submits that he has evolved from a troubled, misguided youth to a model member of the prison community,” the opportunity to demonstrate children responsible for committing heinous crimes are capable of change.

The Supreme Court decision points out that when Montgomery was sentenced, it was automatic. He had no chance to present mitigation evidence, such as his age at the time of the crime, expert testimony related to his incapacity for “foresight, self-discipline, and judgment,” and his potential for rehabilitation.

States may attempt to avoid obeying the new ruling, suggested Lyle Denniston of SCOTUSBlog. A state may choose to not allow inmates the “legal right to use federal law in state courts to attack life without parole sentences, once their convictions have become final in state courts.” Denniston added, “If states take that option, the impact of Monday’s ruling would fall on federal courts and the habeas process in those courts for reviewing convictions that are final.”

The Juvenile Justice Information Exchange described the decision as “potentially sweeping,” but even with the prospect of a new hearing, it would be typical for a judge to deny parole to someone who was a juvenile offender. Until it is unconstitutional for a judge to issue a discretionary life without parole sentence, judges are able to re-sentence individuals to life without parole.

A briefing from The Sentencing Project from October 2015 [PDF] indicates “approximately 2,500 individuals are serving a life sentence without possibility of parole for crimes committed as teenagers.” Around 2,100 of these individuals were “sentenced mandatorily” to life without parole. [Note: The Sentencing Project brief does not state how many of the 2,500 were sentenced for crimes other than homicide.]

In 2012, The Sentencing Project conducted a survey, which found 79 percent of juveniles sentenced to life without prison had “witnessed violence in their homes.” Around a third “grew up in public housing.” Forty percent were “enrolled in special education classes.” Less than half attended school “at the time of their offense.” Nearly half survived physical abuse. Eighty percent of girls reported “histories of physical abuse,” and 77 percent reported “histories of sexual abuse.”

“While 23.2 percent of juvenile arrests for murder involve an African-American suspected of killing a white person, 42.4 percent of [juvenile life without parole] sentences are for an African-American convicted of this crime,” according to The Sentencing Project.

The age range for juvenile offenders is not consistent across states, but most states define a juvenile delinquent as someone under the age of 17.

Jasmine Heiss, senior campaigner with Amnesty International U.S.A., reacted to the Supreme Court’s decision, “While every other country in the world rejects the punishment of life without parole for children, the U.S. remains the only country that locks up kids and throws away the key.”

“This decision represents an opportunity for the United States to chart a bold new direction toward reform in juvenile justice, and for the U.S. criminal justice system as a whole,” Heiss continued. “This ruling comes as the United States is grappling with the very real human rights crisis of mass incarceration. It should not stop here.”

Human Rights Watch called the Supreme Court’s decision “encouraging” but pointed out that much more was needed to “ensure that children who commit crimes in the U.S. are held accountable fairly.”

“All U.S. states should abolish [juvenile life without parole] sentences for all children in all cases, end the practice of trying children as adults unless in exceptional circumstances and after the careful consideration of judges, and stop incarcerating child offenders in adult prisons. Congress should pass a broader, pending sentencing reform bill that includes provisions to eliminate federal [juvenile life without parole] sentences,” Human Rights Watch’s Alison Parker wrote.

Hours after the Supreme Court decision, President Barack Obama’s op-ed against solitary confinement appeared online at the Washington Post. Obama announced a ban on solitary for juveniles in federal prisons.

Yet, as the Post added, only a handful of juveniles are recommended for solitary each year. “Between September 2014 and September 2015, federal authorities were notified of just 13 juveniles who were put in solitary in its prisons.” The bigger issue is what to do for the juveniles in prisons, which are not under the control of the federal government.