When the federal Supreme Court in June declared mandatory life-without-parole sentences unconstitutional for juveniles, experts expected Pennsylvania's more than 500 juvenile lifers to flood the courts with requests to reconsider their sentences.

The floodgates will close Friday, the deadline under the state's Post-Conviction Relief Act, which gives inmates 60 days from the time of such rulings to file appeals.

Advocates believe most of the state's juvenile lifers have filed for reconsideration. Pennsylvania has more juvenile lifers than any other state in the country.

"We have done everything we could do to educate, inform and mobilize this community," said attorney Marsha Levick, deputy director of the Juvenile Law Center.

The state Supreme Court will hear arguments Sept. 12 on two cases whose outcomes are expected to serve as precedent.

Pennsylvania has a fifth of the country's 2,500 juvenile lifers, a distinction resulting from tough, mandatory sentencing. Anyone arrested for murder in Pennsylvania automatically is charged as an adult, and a conviction of first- or second-degree murder carries a mandatory life-without-parole sentence.

Supreme Court justices in June, citing scientific research showing that juveniles don't fully mature until their mid 20's, declared that sentence inhumane for juveniles and recommended it be used sparingly. The decision followed an earlier ruling that banned life-without-parole sentences in nonhomicide offenses.

Contact Dana DiFilippo at difilid@phillynews.com or 215-854-5934. Follow her on Twitter @DanaDiFilippo. Read her blog at phillyconfidential.com.