Fr Lawrence Murphy died in 1998 with no official blemish on his record
The Vatican says a lawsuit brought against Pope Benedict and two Church officials by a US man who says he was abused by a priest is "without merit".
Vatican lawyer Jeffrey Lena said the lawsuit, filed in a Milwaukee court, "rehashes old theories already rejected by US courts".
Lawyers for the alleged victim want the Church to release any files it has on sexual abuse cases involving priests.
The man says he was sexually abused by the late Father Lawrence Murphy.
Fr Murphy has been accused of abusing up to 200 children during his 20 years at a school for deaf children in Milwaukee.
Mr Lena said in a statement: "While legitimate lawsuits have been filed by abuse victims, this is not one of them."
He said the lawsuit was "an attempt to use tragic events as a platform for a broader attack" on the Church.
The statement added that the Pope, as head of a sovereign state, has diplomatic immunity from prosecution in other countries.
'Failed to act'
The US lawsuit alleges that the Pope - in his former role as Cardinal Joseph Ratzinger - and two senior Vatican officials failed to act when the US Church reported the alleged abuse by Fr Murphy in the 1990s.
The Vatican has defended the role of the Pope during the abuse scandal
The other officials named are Vatican Secretary of State Cardinal Tarcisio Bertone and former secretary of state Cardinal Angelo Sodano.
At that time the Pope - as Cardinal Ratzinger - was the head of a Vatican department that considered the Murphy case.
Jeff Anderson, the lawyer of the alleged victim, who has not been named, says his client suffered "severe emotional distress" because of a lack of action.
He said the Vatican had been negligent.
"What we want the Vatican to do is step up to disgorge the secrets that they have in their files," he told the BBC.
He said his client was not seeking money but wanted the Church "to fundamentally come clean, to come forth with all documents that have evidence of crimes against children for decades".
In recent months the Vatican has become embroiled in a wave a sexual abuse allegations against Catholic priests around the world.
On Friday the bishop of the Belgian city of Bruges resigned after admitting sexually abusing a boy earlier in his career.
Bishop Roger Vangheluwe, 73, said the abuse had happened when he was a priest and continued when he started as a bishop, a Vatican statement said.