An elderly nun, under questioning by a lawyer, recently said she could remember almost nothing about his client, a child who had been sexually molested by a Roman Catholic priest.
Lawyer Irwin Zalkin was puzzled because church records showed she had heard several complaints about the San Diego priest, and the file noted that she had reported them to higher authority.
Finally, Zalkin asked whether she was familiar with "mental reservation" -- a 700-year-old doctrine by which clerics may avoid telling the truth to protect the Catholic Church.
"She explained in her own way that it is 'to protect the church from scandal.' She said she subscribed to the doctrine," Zalkin said. "What are you going to do?"
Mental reservation is not sanctioned in canon law, experts say, and is infrequently invoked. But in litigation arising from clergy sex abuse cases in the Los Angeles Archdiocese, at least half a dozen lawyers representing victims report having encountered it.
The idea goes back to times when there were two separate court systems: ecclesiastical, or church courts, and civil courts run by the state. Today, all disputes are settled in civil courts.
The doctrine has been used in modern times to "claim that it is morally justifiable to lie in order to protect the reputation of the institutional church," said Thomas P. Doyle, a Virginia priest who is an expert in canon law and has been widely consulted by lawyers for people who say they were victims of abuse.
It has been misused "to justify lying," Doyle said last week. The doctrine is "not accepted church teaching" but has been widely discussed by scholars and moral theologians, Doyle said.
Zalkin's experience was unusual but not unique.
A lawyer preparing one of the more than 500 claims of abuse against the Roman Catholic Archdiocese of Los Angeles asked a priest giving a sworn statement the same question earlier this month. His lawyer quickly intervened, telling the priest not to answer.
Cardinal Roger M. Mahony in Los Angeles and Bishop Robert H. Brom in San Diego were asked about it while giving sworn statements.
In Boston, where the national scandal broke in 2002 and forced the resignation of Cardinal Bernard Law the following year, the doctrine of mental reservation was "a major concern," lawyer Jeffrey A. Newman said.
"Our concern was that there might have been an internal usage of the doctrine and an understanding of how it would be applied, and we would not be able to decipher it," said Newman, the lead attorney representing a group of 500 claims against 120 priests that was settled three years ago in Boston.
Newman questioned Law under oath before the cardinal resigned and said that Law downplayed the doctrine. Newman said he had received calls from many lawyers seeking consultation about the effect of the doctrine on clergy cases nationwide.
In Northern California, where the claims of 180 people against eight dioceses were settled for about $200 million, the doctrine rarely appeared, said Rick Simons, the Hayward lawyer in charge of litigation for the victims.
"But there were a lot of [priests] up here who did believe they don't answer to the civil authorities, that no one but the church has the power to discipline priests.
"Whether they lie because they think it is a constitutional right, whether they lie because they think it is church doctrine, or whether they lie because they think they'll be prosecuted -- I don't care," Simons said.
When Mahony made a sworn statement under questioning several years ago, he was asked by Irvine lawyer John Manly whether he was testifying under the doctrine. Church lawyers refused to allow Mahony to answer.
"Cardinal Mahony has always insisted and will always insist that honesty always prevails in giving testimony under oath," his spokesman, Tod Tamberg, said Friday. Tamberg said asking the question was "insulting and unprofessional" because it suggested that Mahony wasn't being honest.
Brom, the San Diego bishop whose diocese filed for bankruptcy protection Feb. 27, used a hypothetical to explain the doctrine during his deposition. About 140 claims of abuse are pending in San Diego, and the bankruptcy filing was designed to give the church time to settle those cases.
According to Zalkin, Brom said, "Let's assume we were in Nazi Germany. Let's assume I was harboring a Jewish family in my church. Some Nazis came and knocked on the door and asked me if there were Jews here. In invoking the doctrine of mental reservation, I would be able to say no, which would be a lie and a sin.
"By reserving unto my own mind that the real complete answer would be 'No, not here at this point in time,' or 'No, not standing here in this room.' With that qualification in mind, I'm not lying and I'm not a sinner."
"You really don't know," Zalkin said. "You put somebody under oath; you assume they understand that under civil law they would be committing perjury to lie. It complicates that process when there is a doctrine that allows for a lie to avoid scandal to the church."
How priests and church workers testify bears directly on what has become central to the lawsuits in Los Angeles: whether Mahony and his predecessors at the head of America's largest Catholic archdiocese failed to protect young congregants from known pedophile priests.
Both sides spent years trying to negotiate a settlement of claims, as was done successfully in Orange County two years ago. It has been only over the last several months that the investigation has resumed, resulting in depositions and the surrender of church files such as those that revealed differences in Mahony's descriptions of priestly wrongdoing to congregants here and to church officials in Rome.
Doyle has noted that the oath newly minted cardinals take before the pope includes the vow that they will never tell secrets "the revelation of which could cause damage or dishonor to the Holy Church."
The problem is lack of certainty. "You're never going to know the truth, one way or the other," Zalkin said. "If she says 'No,' you don't know. If she says 'Yes,' you don't know."