Pennsylvania's Supreme Court agreed Thursday to resolve the contested key legal theory underpinning the landmark 2012 prosecution of the first Catholic Church official charged in the clergy child-sex-abuse scandal.

The state's highest court will thus decide the future of Msgr. William J. Lynn, the former Archdiocese of Philadelphia official responsible for investigating and recommending punishment for priests accused of sexual and other misconduct.

It could also dictate the standards for prosecutors to bring future charges against any church officials accused of covering up misconduct by clergy they supervise.

The court did not set a date for oral argument or even a briefing schedule for what will be months of legal filings by the Philadelphia District Attorney's Office and lawyers for the archdiocese and Lynn.

"I'm a little disappointed," said Thomas A. Bergstrom, Lynn's lead attorney, who had asked the court to let stand last year's Superior Court decision reversing Lynn's conviction on a count of child endangerment. "On the other hand, the fight goes on and we'll see."

Tasha Jamerson, spokeswoman for the District Attorney's Office, said there was no comment on the Supreme Court decision.

It came about two months after District Attorney Seth Williams formally asked the court to reinstate Lynn's conviction, involving his supervisory role over a known predator priest who went on to assault another child in 1999.

In July 2012, after a 13-week trial and 121/2 days of deliberations, a Common Pleas Court judge sentenced Lynn to three to six years in prison. Lynn immediately went into custody.

The jury found that Lynn allowed the Rev. Edward V. Avery, who had a history of sexually abusing children, to live in a Northeast rectory, where he assaulted a 10-year-old altar boy. Avery pleaded guilty in 2012 and was sentenced to 21/2 to five years in state prison.

But on Dec. 26, a three-judge Superior Court panel reversed Lynn's conviction, agreeing with his lawyers that it could not be affirmed under the original child-endangerment law or the amended version enacted in 2007.

Bergstrom argued that the pre-2007 version required direct personal supervision of a child. As the archdiocese's secretary of clergy, he said, Lynn was just a "supervisor of a supervisor."

And the post-2007 law, which enabled prosecution of church officials for crimes committed by priests they supervised, could not be retroactively applied to Lynn, who left the clergy secretary post in 2004 after 12 years, he said.

The District Attorney's Office argued that Superior Court wrongly interpreted the original statute to mean "direct supervision."

In accepting the appeal, the justices asked the lawyers to argue the direct-supervision question under the pre-2007 law.

But they also asked them to address whether Lynn could be convicted as an "accomplice" to a scheme in which sexually deviant priests were reassigned to places they could prey on other children.

Following the Superior Court ruling, the 63-year-old cleric was released from prison Jan. 2, after the archdiocese of posted bond for his $250,000 bail. He lives in the rectory of St. William, a parish in Lawncrest, on electronically monitored house arrest.