The U.S. Supreme Court on Monday expanded its ban on mandatory sentences of life in prison without parole for people who committed a crime before age 18, siding with a 69-year-old Louisiana man convicted in the 1963 murder of a sheriff’s deputy.

The 6-3 ruling, with conservative justices Anthony Kennedy and John Roberts joining the court’s four liberals, was the latest by the high court to protect juvenile offenders from the harshest sentences.

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The court in 2012 had ruled that mandatory life sentences violated the U.S. Constitution’s ban on cruel and unusual punishment. The justices, in their ruling on Monday, said that their 2012 ruling could be applied retroactively to inmates convicted before that decision was issued.

In a ruling that will affect other prisoners in similar positions, the court sided with black inmate Henry Montgomery, convicted of killing a white sheriff’s deputy in 1963 in East Baton Rouge at a time when racial tensions in the region were boiling over.

Montgomery and up to 2,300 people serving similar sentences around the United States could be resentenced or given the chance to apply for parole in light of Monday’s ruling, according to John Mills, an attorney at the Phillips Black Project, a public interest law firm.

Justice Antonin Scalia dissented from the ruling along with fellow conservatives Clarence Thomas and Samuel Alito. Scalia described the ruling as “a devious way of eliminating life without parole for juvenile offenders.”

Lower courts had been divided over whether inmates who have already gone through the appeals process can benefit from the high court’s decision in the 2012 case, Miller v. Alabama.

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The court held then that the Constitution forbids such mandatory life sentences without parole for juveniles convicted of murder.

In 2005, the Supreme Court banned capital punishment for those under 18 at the time of their crimes. In 2010, the justices prohibited sentences of life without parole for juveniles’ crimes short of murder. In 2012, it ruled against mandatory life without parole for any offense including murder.

In Monday’s ruling, authored by Kennedy, the court said the 2012 ruling could be applied retroactively because it was a substantive change to the law.

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Although the court in 2012 had not altogether barred mandatory life without parole sentences, it was reserved for crimes reflecting “irreparable corruption,” Kennedy said.

Therefore, the 2012 ruling “did more than require a sentencer to consider a juvenile offender’s youth,” he added.

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Kennedy said Montgomery himself had showed “his evolution from a troubled, misguided youth to a model member of the prison community.”

(Reporting by Lawrence Hurley; Editing by Will Dunham)