A spokesman for the archdiocese declined to comment.
Hamilton declined Friday to detail the allegations until the suit was filed or to identify the accused priest in the latest case, except to say he is no longer a priest and had been named in the 2005 grand jury report of abusive priests.
A news release about the lawsuit described the defendant as a former pastor at Our Lady of Calvary Church. The 2005 report said one former pastor there, the Rev. Stanley Gana, "sexually abused countless boys."
Hamilton said that the lawsuit would name the plaintiff only as a John Doe, but that the plaintiff was considering publicly identifying himself during a news conference scheduled for Monday. Other abuse victims will also attend, she said.
Similar suits failed in the past, largely because of the statute of limitations. But the attorneys say they believe the grand jury's searing conclusions have given them new legal standing to pursue civil claims against the archdiocese.
Among other things, the panel concluded the church's victim-assistance program has at times appeared to be less interested in helping victims than in protecting priests and church leaders.
In the weeks since the grand jury report, church officials have acknowledged failings in the system, apologized, and pledged to improve. Cardinal Justin Rigali also announced new positions and procedures for handling abuse allegations, and hired a former sex-crimes prosecutor to review dozens of old claims.
Hamilton said the report has also stirred more victims to come forward. Asked if more lawsuits were looming, she said: "Many, many more."
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