The suit was filed Wednesday in the Philadelphia Court of Common Pleas by the family of a man identified as "Ben" in a scathing grand jury report that alleges the archdiocese covered up sex abuse cases.
The lawsuit says "Ben" was abused in the 1980s by the Rev. Joseph Gallagher, a priest who had previously been accused of sex abuse.
"Ben" killed himself after the archdiocese deemed his allegations not credible in 2008.
Gallagher was suspended in February. An archdiocese spokesman declined to comment on the suit.