FILE - In this March 27, 2012 file photo, Monsignor William Lynn leaves the Criminal Justice Center in Philadelphia. Lynn served 18 months of his three-to-six-year term for child endangerment before the state Superior Court overturned his conviction on Thursday, Dec. 26, 2013. (AP Photo/Alex Brandon, File)

PHILADELPHIA - Lawyers for a Roman Catholic church official will demand his immediate release from prison Monday after an appeals court overturned his conviction in a novel priest-abuse case aimed squarely at the church hierarchy in Philadelphia.

Monsignor William Lynn, 62, is the first Catholic official ever prosecuted over his handling of priest sex-abuse complaints. He has served 18 months of the 3- to 6-year sentence handed down by a judge who said he helped predators remain in ministry, endangering new victims.

But the Superior Court threw out the conviction Thursday, ruling that the state's child-endangerment law did not apply in the late 1990s to church supervisors like Lynn. The Superior Court said the case never should have been filed.

"The laws at that time were inadequate to deal with this kind of problem. And I think that the judge and the prosecutor stretched the law, trying to find some way to punish somebody," the Rev. Thomas Reese, a Jesuit theologian and senior analyst with the National Catholic Reporter, said Friday. "They stretched the law too far, in the opinion of the appeals court."

The bail issue now moves back to the trial judge, Common Pleas Judge M. Teresa Sarmina, who had upheld the charges and ultimately blasted Lynn for failing to stand up to his bishops. Lynn won't be in court Monday to face her for the first time since his July 2012 sentencing.

However, his lawyers filed a bail petition seeking immediate action "in light of the unequivocal language of the Superior Court opinion, as well as the amount of time Msgr. Lynn has already served." Prosecutors vowed a fight to restore Lynn's conviction, and will oppose bail.

Even if Lynn goes free, his long ordeal offers "a warning, to every 'yes man' in the church, that that can get him in trouble," Reese said.

The three-month trial last year painted Lynn, the secretary for clergy, as a loyal if timid aide to Cardinals Anthony Bevilacqua and Justin Rigali. He documented hundreds of abuse complaints filed against dozens of priests at the archdiocese from the late 1950s through his 1992-2004 tenure, then locked the explosive files in a secret archives room. The accused priests were often transferred to new parishes without warning, although Lynn said he often tried to get them and their victims help.

Prosecutors tracked down many of the scarred victims from the secret files. Sarmina allowed 20 of them to testify about their sordid childhood encounters with trusted priests, even though the crimes were too old to prosecute. They described countless rapes, sadist religious rituals and failed attempts to get help from other adults.

The Superior Court never ruled on whether that graphic testimony was appropriate at Lynn's trial. But the testimony served as something of a "truth and reconciliation" panel for Catholics, Reese said.

The defence has long argued that Lynn was charged retroactively under a 2007 law that broadened the scope of the child-endangerment law to include those who supervise predators. Sarmina, though, had rejected the argument. The Superior Court found her ruling "fundamentally flawed."

Lawyers who represent victims suing the Philadelphia archdiocese doubt the reversal of Lynn's conviction, if it sticks, will affect their civil cases. They could cost the church millions, but had been on hold during the criminal case.

"This was a landmark prosecution based on landmark revelations," said lawyer Jeff Anderson of St. Paul, Minn., who represents scores of priest-abuse accusers. "As disappointing as the overturning of that conviction is, it really is a small piece in a larger picture that has now been revealed, like no place ever before."

News from © The Associated Press, 2013