Court documents show Vatican lawyers plan to argue that the Pope has immunity as a head of state, that American bishops who oversaw abusive priests were not employees of the Vatican, and that a 1962 document is not the "smoking gun" that provides proof of a cover-up.
The Holy See is trying to fend off the first US case to reach the stage of determining whether victims actually have a claim against the Vatican itself for negligence for allegedly failing to alert police or the public about Roman Catholic priests who molested children.
The case was filed in 2004 in Kentucky by three men who claim they were abused by priests and claim negligence by the Vatican. Their lawyer, William McMurry, is seeking class-action status for the case, saying there are thousands of victims across the country.
Mr McMurry said: "This case is the only case that has been ever been filed against the Vatican which has as its sole objective to hold the Vatican accountable for all the priest sex abuse ever committed in this country.
"There is no other defendant. There's no bishop, no priest."
But the Vatican is seeking to dismiss the suit before Pope Benedict XVI can be questioned or documents subpoenaed.
The preview of the legal defence was submitted last month in US District Court in Louisville. The Vatican's strategy is to be formally filed in the coming weeks. Vatican officials have refused to comment.
Plaintiffs in the Kentucky suit argue US diocesan bishops were employees of the Holy See and Rome was therefore responsible for their alleged wrongdoing in failing to report abuse.
They say a 1962 Vatican document mandated that bishops not report sex abuse cases to police but the Vatican has argued that there is nothing in the document that prevented bishops from doing so.
With the US scandal revived by reports of abuse in Europe and scrutiny of Benedict's handling of abuse cases when he was archbishop of Munich in Germany, the Kentucky case and another in Oregon have taken on greater significance.
Lawyers as far away as Australia have said they plan to use similar strategies.
But the hurdles remain enormously high to force a foreign government to turn over confidential documents, let alone to subject a head of state to questioning by US lawyers.
The US considers the Vatican a sovereign state – the two have had diplomatic relations since 1984.
"They will not be able to depose the Pope," said Joseph Dellapenna, a professor at Villanova University Law School and the author of Suing Foreign Governments And Their Corporations.
"But lower level officials could very well be deposed and there could be subpoenas for documents as part of discovery."
Mr McMurry last week filed a new court motion seeking to depose the Pope; Cardinal Tarcisio Bertone, currently Vatican secretary of state but for years the Pope's deputy at the Congregation for the Doctrine of the Faith; Cardinal William Levada, an American who currently heads the congregation; and Archbishop Pietro Sambi, the Vatican's US representative .
Yesterday, Mr McMurry filed a memorandum in support of his demand to question Benedict based on court documents unearthed last week detailing the role of the congregation in shutting down a canonical trial for a Wisconsin priest who allegedly molested up to 200 deaf boys.