VATICAN CITY — The image must have been jarring for many American Catholics: Cardinal Bernard Law, the embattled former archbishop of Boston, on a throne atop the tomb of St. Peter, where Pope John Paul II so often sat.

Yesterday, Law celebrated one of the nine special Masses at St. Peter's Basilica mourning the late pope, and few of the worshippers in the vast basilica seemed to have any idea who he was.

Vatican officials downplayed his presence, saying that as an archpriest of one of the papal basilicas in Rome — a largely ceremonial role he received after resigning the Boston post — he automatically was slated to preside over the Mass.

But for some Americans, who have come to regard Law as a symbol of the wrenching priest-sexual-abuse scandal, his presence at the center of one of the church's most-solemn moments, more than two years after leaving Boston in disgrace, provoked strong reactions.

Two activists with a Chicago-based group for victims of priest sexual abuse traveled to Rome to protest Law's role. They intended to hand out leaflets, and they attracted many reporters but few passers-by before Vatican security escorted one of the women from St. Peter's Square.

"We believe that he should have recused himself" from celebrating the Mass for Pope John Paul II, said the woman, Barbara Blaine of Chicago. American cardinals should have intervened when Law did not withdraw, she added.

Law's appearance drew attention in part because there was little other news from the Vatican yesterday. But the curious episode also highlighted the gulf in understanding that often persists between Catholics in America and church leaders in Rome.

During the scandal's most-searing moments in 2002, many American Catholics could not understand why the Vatican remained so quiet, and seemingly unperturbed, about the growing crisis.

Some Catholic bishops and cardinals from other parts of the world, meanwhile, said the scandal was overblown and media-driven.

And many Vatican insiders pointed out that Americans make up only 6 percent of the world's Catholics, so their problems must vie with the troubles of other believers around the world for the attention of church leaders.

Law first offered his resignation in April 2002, feeling pressure from a series of disclosures that he had known of abuse allegations but kept them quiet as he transferred suspect priests to other parishes. The pope turned him down.

Only in December 2002, with the archdiocese of Boston in an uproar and facing financial ruin from more than 100 lawsuits, did the pontiff accept Law's resignation.

If that moment did not loom large at the Vatican, it does for Blaine.

"Cardinal Law is like the poster child for the sex-abuse scandal in the American church. When Catholics in the parishes see the image of Cardinal Law, they feel pain," Blaine, a leader of the Survivors Network of those Abused by Priests, said after arriving in Rome yesterday.

Cardinal Justin Rigali of Philadelphia celebrated yesterday's Mass jointly with Law, but few other American cardinals were there.

Some, including Cardinal Francis George of Chicago, declined to comment about the event, citing an agreement among the cardinals not to talk to the news media in the week leading up to the conclave that will choose the next pope.

George's spokeswoman said he did not attend the Mass because of the increasing demands of the cardinals' daily meetings.

Law did not allude to the scandal during the Mass and did not speak to reporters outside. His homily, delivered in Italian, focused on the bond between John Paul II and Rome, and the powerful effect his life, death and mourning had on people's faith.

Chicago Tribune correspondents Manya A. Brachear in Rome and Margaret Ramirez in Chicago contributed to this report.