HARRISBURG, Pa. (AP) - Changes are coming to Pennsylvania's sex offender registry as a result of a Pennsylvania Supreme Court decision issued this week, but experts say it's unclear exactly how they will play out.

The justices said 2012 changes to the registry that expanded and toughened reporting rules under the state's Megan's Law can't be applied retroactively, ruling in favor of Jose Muniz, convicted in Cumberland County of two counts of indecent assault of a 12-year-old girl.Under the state's Megan's Law, offenders had to register and report for either 10 years or life, but the 2012 enactment of the Sex Offender Registration and Notification Act changed that to 15 years, 25 years or life, causing many offenders who had been in the midst of a 10-year reporting period to have to remain registered for life.The court said Muniz was not subject to the harsher penalties of the Sex Offender Registration and Notification Act, and now agencies are trying to sort out what that means for other convicted sex offenders.Ryan Tarkowski, a spokesman for the state police, which run the Megan's Law website, said the court's decision may result in the removal from the registry of sex-crime offenders who committed their crimes before the new version of the law took effect five years ago.He called the ruling "a complex decision" that will "undoubtedly impact" management of the registry. Tarkowski said it it's too soon to know how many offenders will be removed.The 55-page decision, which was accompanied by a concurring opinion and a dissent, is now being reviewed by department lawyers and other agencies, including the Board of Probation and Parole, Tarkowski said.State police are assessing the decision's impact and working on "an appropriate course of action" to comply with the new court decision, as well as state and federal laws.When the new law took effect in December 2012, there were just over 12,000 registrants in the system, and about half of them had to register for life, said Aaron Marcus, an appellate lawyer with the Defender Association of Philadelphia. Marcus, who wrote a friend-of-the-court brief in the Muniz case, said that by this time last year, there were nearly 20,000 registrants, and about three-quarters of them had to register for life.He estimates that about 4,500 offenders who were already on the Megan's Law registry in 2012 were reclassified. It's likely that many will seek to return to a 10-year registration period."You can be assured that our office will be looking at these cases very closely and ensuring that all of the rights of our clients are protected," Marcus said. "You can't punish somebody that had no idea punishment would exist at the time of the offense."Part of the Supreme Court's decision was that the registration requirement constitutes a form of punishment, a distinction that legal experts said could have implications for how the system will work in the future.Cumberland County District Attorney Dave Freed, whose office prosecuted Muniz, said the decision raises questions about whether the current law provides the sorts of procedures normally required when a court is handing down punishment."What do we have to do in order to impose it? I don't know that we know the answer to that question," Freed said. "Does that have to be decided by a jury? What sort of notification requirement is there?"Marcus said offenders might also use the classification of the registry as punishment to argue they have a right to try to convince a court that they are not dangerous and not at risk of re-offending."The conviction alone doesn't mean future dangerousness," Marcus said.The decision also has drawn attention from the victims of sex offenders, said Jennifer Storm, the state's victim advocate. Her office currently keeps more than 3,900 victims notified about the status of Megan's Law registry offenders, including changes in their jobs or where they live."The majority want these notifications, because for them it is a matter of their safety and their peace of mind," Storm said. "I think we're going to need to look at legislatively, what can we do to ensure the registry is beyond reproach."