Pennsylvania's Supreme Court on Monday issued a ruling that will make it far more difficult to sentence any juvenile to life without parole — a striking about-face in a state that is home to the largest population of juvenile lifers in the nation.

In the case of Qu'eed Batts, who has twice been sentenced to life in prison with no possibility of parole, the court ruled that there is a presumption against life sentences for juveniles — and that in order to sentence a minor to life, prosecutors must prove beyond a reasonable doubt that he or she is incapable of rehabilitation.

Batts was 14 and in a gang when he shot and killed another teen in Easton,. He appealed following a pair of U.S. Supreme Court decisions: Miller v. Alabama, which found automatic life-without-parole sentences unconstitutional, and Montgomery v. Louisiana, which ruled that states like Pennsylvania that had declined to apply the Miller ruling retroactively must do so.

"What we won is really fundamental to giving these kids a fair shot, and also to really enforcing Miller and Montgomery in Pennsylvania," said Marsha Levick, deputy director of the Philadelphia-based Juvenile Law Center, who argued the case for Batts. "Initially ruling that Miller wasn't retroactive in 2013 was a misstep by the court, to stay the least. Now that we are conforming as a consequence of Montgomery, I think the Pennsylvania Supreme Court has recognized the nature of those decisions and is ensuring those sentences are only imposed in the rarest of circumstances."

In the U.S. Supreme Court rulings, the justices connected the impulsiveness associated with youth to diminished culpability, and said "children who commit even heinous crimes are capable of change."

About two-thirds of the more than 300 juvenile lifers from Philadelphia are still awaiting new sentences. The Philadelphia District Attorney's Office has said it will seek life sentences in just a handful of those cases.

The rest are being re-sentenced to terms guided by a state law passed in 2012 that set minimums ranging from 20 years to life to 35 to life, depending on the nature of the crime and on the perpetrator's age at the time. The state Supreme Court's decision Monday affirmed that minimum sentences should be guided by the current state law.

One Philadelphia man who could face life without parole once again is Andre Martin, who was 15 when he shot and killed a police officer, John Trettin, in 1976. Louis Natali, who is representing Martin, declined to speak to the ruling's effect on his client's case.

Ronald Eisenberg, deputy of the law division at the Philadelphia District Attorney's Office, said the ruling would likely trigger some procedural changes in rare cases like Martin's.

But, he added, "the defense had asked the court to go further and have a whole separate proceeding, like you have to do in capital case with a jury. The court rejected that proposal."

Batts' case was precedent-setting for juvenile lifers across the state; however, many more legal questions are still to come before the court, according to Bradley Bridge, who is leading the representation of more than 200 juvenile lifers for the Defender Association of Philadelphia.

For one, he is challenging the life-imprisonment maximum sentence being imposed on all juvenile lifers on behalf of his client Joe Ligon, who is 80 and was re-sentenced to 35 years to life after 64 years in prison.