More than 50 people sentenced to life in prison in Arkansas when they were younger than 18 could get those sentences reconsidered, thanks to a new court decision.

The Arkansas Supreme Court ruled Friday that a U.S. Supreme Court decision three years ago applies retroactively in the state, the Arkansas Democrat-Gazette reported.

In 2012 the U.S. Supreme Court held in Miller v. Alabama that imposing an automatic life sentence without parole on someone younger than 18 was cruel and unusual punishment and a violation of the Eighth Amendment.

Arkansas is now the 12th state to rule the Miller decision retroactive, according to the Juvenile Law Center — with potentially life-changing consequences for inmates in those states. Since March, Florida and Connecticut have also ruled the decision retroactive, said Emily Keller, staff attorney with the Juvenile Law Center.

In the remaining states, thousands of inmates who committed crimes before they were 18 do not have the same redress. More than 1,000 inmates are in the seven states, including Louisiana and Pennsylvania, that have held that the Miller decision does not apply retroactively, Keller said.

The Supreme Court has agreed to take up the question in the case Montgomery v. Louisiana. It will hear the case in its next term, which begins in October, with a ruling expected within a year, she said.

The Juvenile Law Center estimates that 2,100 people across the country, sentenced when younger than 18, are serving mandatory life sentences without parole.

“Pennsylvania has the biggest population of people serving juvenile life without parole sentences in the country,” Keller said. She estimates the number there to be more than 500.

The Miller case was brought on behalf of Evan Miller, who was 14 when he and another boy set fire to a mobile home. They had bought drugs from a neighbor who lived there. Miller and the friend were convicted of murder and sentenced — at that age — to life without parole.

“Mandatory life without parole for a juvenile precludes consideration of his chronological age and its hallmark features — among them, immaturity, impetuosity, and failure to appreciate risks and consequences,” Justice Elena Kagan wrote in the court’s majority opinion.

“It prevents taking into account the family and home environment that surrounds him — and from which he cannot usually extricate himself — no matter how brutal or dysfunctional,” she wrote.

The U.S. Supreme Court considered the case alongside an Arkansas case, Jackson v. Hobbs. Kuntrell Jackson, 14, received a life sentence for a murder in which he did not pull the trigger. Jackson took part in an armed robbery of a video store. He waited outside and then entered the store just before his companion shot and killed the clerk.

In these cases, the Supreme Court did not forbid life sentences for juveniles. It ruled that judges must consider their youth and the nature of the crime before handing down life without parole.