Five months after approving what many hailed as a groundbreaking policy on sexual abuse by clergy, U.S. Catholic bishops are gathering today in Washington to consider revisions that some call mere fine-tuning - but that critics say will water the policy down.

The revisions were crafted by a joint commission of Vatican officials and U.S. bishops after the zero-tolerance policy failed last month to win final approval from Rome.

Unlike at the June meeting in Dallas, where the bishops deliberated for four agonizing days under unprecedented news media scrutiny, the revised policy is merely one item on a full agenda and will receive considerably less attention. Many observers believe that if the sexual abuse policy is passed in its present form when it comes up for debate and vote Wednesday, it will easily win Vatican approval.

"The people I've talked with feel very positive about it. I feel very positive about it," said Baltimore's Cardinal William H. Keeler. "So I don't anticipate a great deal of heat about it. I think we have a lot of light now, and we're going to move in that direction. I don't anticipate a great deal of debate."

But critics are lining up. Protesters are expected to be a constant presence outside the Hyatt Regency on Capitol Hill, where the bishops are meeting for the next four days. Several groups have planned a candlelight vigil tonight.

"My sense is that the proposed norms take the wind out of the sail of the Dallas document and leave it almost meaningless," said Barbara Blaine, president of the Survivors Network of those Abused by Priests (SNAP).

Some of the changes that have troubled critics include:

While the original policy removed a priest from ministry who committed a single act of abuse, no matter how long ago, the joint commission reinstated the 10-year statute of limitations in church law, which allows an abused minor to make a complaint up to age 28. The revised policy does allow a bishop to petition the Vatican for a dispensation from the statute of limitations.

"One of biggest disappointments is it potentially allows that perpetrators can return to ministry or remain in ministry," Blaine said.

The revised policy makes clear that the review boards that are to be set up in every diocese, with a membership composed primarily of lay people, are to be merely advisory. Final authority in reviewing sexual abuse allegations, it says, must lie with the bishop.

"The laity have a wealth of time, talent and treasure to offer diocesan bishops as they attempt to address the sexual abuse crisis," said Steve Krueger, interim director of Voice of the Faithful, a Boston-based lay group organized in response to the sexual abuse crisis. "Reducing the proposed role of a collaborative ... board to a minor advisory role - and then only after an assessment has already been made by a bishop - is a momentous departure from the envisioned spirit of Vatican II."

The policy as approved in June required church officials to report any allegation of sexual abuse of a minor to secular authorities. The revised policy holds that each diocese must comply with civil law. Clergy are required to report abuse in only about half the states.

Many canon lawyers, specialists in the law that governs the Roman Catholic Church, say the revisions have sharpened and improved the policy. These experts were troubled by what they considered an overly vague definition of sexual abuse in the original policy, which did not even require physical contact.

For one canon lawyer, that brought to mind former President Jimmy Carter's infamous 1976 interview in which he answered a question about adultery by saying he had lusted after women in his heart.

"The old definition would have made Jimmy Carter guilty of sexual abuse," said the Rev. Arthur J. Espelage, executive secretary of the Washington-based Canon Law Society of America.

Espelage also applauded changes that allow a priest to remain in ministry until after a bishop has conducted a preliminary investigation into an allegation and provisions that require bishops to follow procedural rules for church trials, including rules for gathering evidence and evaluating witness testimony.

"It levels the playing field in this sense, that with rule by law and judicial process you have to prove an accusation," Espelage said. "One can never prove a negative, but you should be able to prove a positive."

Likely to be overshadowed by the sexual abuse policy are other significant documents the bishops will consider.

They will vote on the first joint statement by U.S. and Mexican Catholic bishops on migration, which argues that while countries have the right to protect their borders, people have the right to migrate to support themselves and their families. Furthermore, the bishops are expected to say that human dignity and rights of undocumented migrants should be respected.

The bishops will also weigh calling the first "plenary council" - an extraordinary gathering of bishops with binding legislative power -since the last one convened in Baltimore in 1884. Last summer, a group of bishops circulated a petition calling for such a council to reaffirm traditional church teachings, including celibacy for priests.