Accusing state lawmakers of "religious gerrymandering," the Roman Catholic Church is asking a federal judge to declare unconstitutional the California law that opened courthouse doors to hundreds of victims of decades-old sexual abuse by priests.

Lawyers for the Roman Catholic Diocese of Davenport, Iowa, are asking a federal judge in San Diego to void the 2003 statute because they say it violates the church's 1st Amendment right to the free exercise of religion, due process and other constitutional rights.

The case involves a Colorado man who says he was molested by his parish priest, James Michael Janssen, now 83, while the two vacationed in the San Diego area in 1967 and 1968.

"It could potentially lead to the dismissal or invalidation of roughly 800 cases that have been filed in California that previously would have been time-barred," said Susan L. Oliver, a San Diego lawyer representing the Diocese of Davenport.

It also could save the Catholic Church hundreds of millions of dollars that the plaintiffs' lawyer says must be paid to resolve -- through settlement or trial -- the lawsuits.

State lawmakers lifted the statute of limitations for a year, ending Dec. 31, 2003, so victims of childhood sexual abuse could sue institutions that failed to protect them from known molesters in their employ. Hundreds of lawsuits were filed against the Catholic Church and other organizations, such as the Explorers, Salvation Army and Seventh-day Adventist Church.

J. Michael Hennigan, lawyer for the Archdiocese of Los Angeles, said he plans to file a motion this week to intervene in the Davenport case.

"We've thought for a long time there were constitutional problems with those claims," he said, adding that he does not expect the legal challenge to affect settlement talks. He said he hopes the archdiocese will have settled all of the estimated 500 child- molestation claims against it before the constitutionality issue is resolved.

But lawyers for victims are skeptical about the church's legal tactics.

"To me, it seems like kind of a desperate attempt," said Laurence Drivon, a Stockton lawyer who represents 450 alleged victims in pending civil suits against the Catholic Church. "The courts have consistently ruled that retroactivity of the statute of limitations in civil cases is exclusively within the jurisdiction of the Legislature."

The law is a near duplicate of another state statute that reopened a one-year filing window for homeowners to sue insurers for property damage from the 1994 Northridge earthquake. The constitutionality of the quake law has been upheld by state and U.S. appellate courts.

In contrast, diocesan lawyers in their court papers cite the U.S. Supreme Court decision last year that struck down a 1994 California law allowing retroactive prosecution involving older sex crimes against children. But plaintiffs' lawyers say the ex post facto clause of the U.S. Constitution, on which the high court relied in that case, does not apply to civil cases.

Lawyers for alleged victims and the Southern California dioceses have been locked in secret mediation for the past 18 months, trying to resolve the cases without litigation. That has delayed until now any efforts by the Catholic Church to challenge the law's constitutionality.

L.A. County Superior Court Judge Marvin Lager ruled last year on the constitutionality of the 2003 state law. Lager rejected a due- process argument by lawyers for the Seventh-day Adventist Church in an abuse case.

The San Diego claim by the Catholic Church, filed May 25, devotes more pages to scrutinizing possible motives of the plaintiffs' lawyers and their relationships to state lawmakers -- including Sens. Martha Escutia (D-Whittier), John Burton (D-San Francisco) and Joe Dunn (D-Santa Ana) -- than to its constitutional arguments.

In court papers, diocesan lawyers accused legislators, who unanimously approved the legislation in June 2002, of being influenced by the flood of media coverage on the national clergy sex- abuse scandal, including 599 stories in the Los Angeles Times that year on the alleged molestation of hundreds of children by priests.

"The Free Exercise Clause protects the defendants from being the targets of legislation designed to burden and punish them because of their religious beliefs or practices," the claim states. "The history, text and structure of [the law] show it to be a 'religious gerrymander' designed to single out and punish Catholic institutions."

The diocesan lawyers also argue that many of their potential witnesses are dead, making it impossible for them to defend against the allegations.

But Drivon said the plaintiffs' lawyers have the burden of proving their cases, and under the law in question the additional burden of providing collaborative evidence that the abuse took place.

Mary Grant, a regional director of the Survivors Network of Those Abused by Priests, said she is not surprised by the church's latest efforts to shift the blame to others.

"They are always putting the responsibility on the victim, the victim's parents, then they blamed the media for exposing the abuse," she said. "They want to act like the victim. Their words sound good, but their actions are totally opposite of what they are doing."

Tod M. Tamberg, a spokesman for the Los Angeles Archdiocese, said the archdiocese's legal decision to intervene in the case would not interfere with its prevention and outreach efforts, including mediation to try to settle the claims.

He said the archdiocese has released the names of 211 of the 244 priests -- including some still in active ministry -- accused of molestation.