Four months ago, when the nation's Roman Catholic bishops enacted a get-tough policy toward child sexual abuse, few commentators thought they had gotten it just right. Victims' groups said the bishops had not gone far enough. Groups devoted to priests' rights said they had gone too far.

But from the point of view of church leaders seeking to halt an avalanche of scandal that was burying diocese after diocese in lawsuits, the policy had at least one major advantage: clarity. The heart of it was a pledge to remove from public ministry -- though not necessarily to defrock -- any priest who had ever molested a child, no matter how long ago. "From this day forward, no one known to have sexually abused a child will work in the Catholic Church in the United States," declared Bishop Wilton D. Gregory, president of the U.S. Conference of Catholic Bishops.

The Vatican's partial rejection of the policy last week plunged that core promise into uncertainty.

The full impact will remain unknown until a joint commission of four U.S. bishops and four Vatican officials negotiates changes sought by the Holy See. But canon lawyers predict the Vatican will insist on the restoration of a statute of limitations on abuse charges, making it difficult or impossible for U.S. bishops to remove priests on the basis of allegations that often date back 20 or 30 years.

Paradoxically, the Vatican's stated motive is also clarity. Cardinal Giovanni Battista Re, head of the Vatican department for bishops, conveyed the decision in a two-page letter that said the policy adopted by the U.S. bishops in Dallas in June could cause "confusion and ambiguity" because it contains provisions that "are difficult to reconcile with the universal law of the Church." Some of the terminology in the policy, he added, is "vague or imprecise and therefore difficult to interpret."

Officials in Rome said the letter was referring to the policy's lack of a workable definition of sexual abuse and its stipulation that "for even a single act of sexual abuse of a minor -- past, present or future -- the offending priest or deacon will be permanently removed from ministry." Other Vatican objections, they said, include the establishment of lay review boards in each diocese that could usurp the local bishop's responsibility to investigate allegations, weigh any extenuating circumstances and mete out appropriate penalties.

In short, the Vatican was concerned that the U.S. bishops, in taking a blanket approach to an urgent problem, had abruptly thrown aside "due process" protections built up over centuries in canon law, the church's internal legal code.

The Rev. Thomas J. Reese, editor of the Catholic magazine America, said, "Parents should be assured that Re's letter does not mean that abusive priests will be back in parishes tomorrow."

Some U.S. church leaders, including Gregory and Cardinal Theodore E. McCarrick of Washington, cast the Vatican's decision as a welcome intervention that in the end would strengthen, not weaken, the so-called zero-tolerance policy. McCarrick spoke of the need for some "tinkering" with the policy before the U.S. bishops meet in Washington next month. Gregory emphasized the Vatican's overall support for the American bishops' efforts and said no one in Rome had told them to stop carrying out the Dallas policy.

Although Gregory and McCarrick argued that the policy remains in effect, several leading canon lawyers have argued that without a "recognitio," or formal approval, from the Vatican, the provisions that conflict with pre-existing church law are not binding on individual bishops and can be overruled by church courts. And although there is room for disagreement about which provisions depart from the church's universal law, the lack of a statute of limitations is certainly among them.

As a letter from the Vatican to all U.S. bishops last year reiterated, canon law specifies that for alleged incidents of child sexual abuse committed before Nov. 27, 1983, the clock runs for five years from the date of the offense; for offenses committed before April 25, 1994, it runs for five years after the victim's 18th birthday; and for offenses committed after April 25, 1994, it runs for 10 years after the victim turns 18.

Groups defending the rights of priests say that dozens of Catholic clergymen have appealed to church courts to overturn their punishment on sexual abuse charges, and that many more will now do so.

"Four or five years ago, a priest would just fall down and roll over. Not any more. They're starting to fight," said Michael Higgins, executive director of Justice for Priests and Deacons, a San Diego-based group. Higgins himself was dismissed from the clergy in 1999 for allegedly soliciting sex in the confessional, a charge he adamantly denies.

David Clohessy, executive director of a leading victims' group, the Chicago-based Survivors Network of Those Abused by Priests, said he is worried that bishops who have been uncomfortable with the zero-tolerance policy will now feel free to ignore it.

"I have always thought the Dallas policy was too weak," Clohessy said. "But the one reason many Catholics felt positively about Dallas was the clarity of the charter, and now it's gray."

People receive communion from Monsignor John Ferry, left, and the Rev. Michael Rajendian in New York on Friday, the day the Vatican rejected the U.S. Catholic Church's sex abuse policy.