PHILADELPHIA — A Roman Catholic monsignor could leave prison after 18 months after a Pennsylvania appeals court reversed his unusual conviction in the clergy-abuse scandal.

Monsignor William Lynn is the first church official ever convicted over his handling of abuse claims. However, an appeals court has thrown out his case, saying he was tried under a child-endangerment law that didn’t apply to him.

His lawyers will be in court today to ask Common Pleas Judge M. Teresa Sarmina to release the priest.

Lynn is the former secretary for clergy in the Philadelphia archdiocese, a post he held from 1992-2004.

Philadelphia prosecutors vow to appeal last week’ decision and restore Lynn’s conviction.