When several Catholic bishops argued last year that they had a responsibility to deny Holy Communion to politicians who support abortion rights, Baltimore's Cardinal William H. Keeler was not among them. He instead offered that taking the sacrament was a personal matter, saying, "We don't need bishops to get into the act."

Keeler said yesterday that he was not doing a turnabout in boycotting Loyola College of Maryland's commencement ceremony today. Keeler is not attending because of the abortion-rights stance of the keynote speaker, former New York Mayor Rudolph W. Giuliani.

In each instance, the cardinal said, he was supporting church guidelines.

Catholic experts said yesterday that a policy adopted in June by U.S. bishops discouraging colleges from honoring abortion rights supporters, such as Giuliani, is subject to wide interpretation.

"It's not entirely clear" who should be barred from honors, said the Rev. James L. Heft, a professor of faith and culture at the University of Dayton.

But most observers doubted that Keeler was reacting to any pressure from the new conservative papacy of Pope Benedict XVI.

"This is a man who believes in the right to life, period," said George Weigel, a theologian and senior fellow at the Ethics and Public Policy Center in Washington. "No one should be surprised that [Keeler's] taken a firm, strong stand on this issue."

The cardinal is chairman of the U.S. Conference of Catholic Bishops' Committee for Pro-Life Activities and has delivered speeches before the annual Right to Life march in Washington.

In a letter Tuesday to Loyola's interim president, David Haddad, Keeler said: "There will be no representative of the Archdiocese participating in any event honoring former Mayor Giuliani."

Archdiocese spokesman Sean Caine said Keeler's absence, and his refusal to send a representative, was intended to convey "his disappointment in [the college's] decision to honor Mr. Giuliani," who has publicly backed abortion rights.

Keeler has, in fact, never attended a Loyola commencement ceremony but has often sent a representative.

Caine said Keeler decided on the boycott because of the policy he helped write for the bishops conference.

The policy, drafted after last year's commencement season, states: "The Catholic community and Catholic institutions should not honor those who act in defiance of our fundamental moral principles. They should not be given awards, honors or platforms which would suggest support for their actions."

The bishops wrote the policy as more and more prominent Catholic politicians, and sought-after commencement speakers, described themselves as supporting abortion rights.

With Keeler's decision, he became one of two bishops in the country to take action this year against a Catholic college's commencement, even as 17 church schools are hosting speakers and degree recipients that conservative Catholics deem inappropriate.

Keeler said he would not take further action against the school, even as it went forward with plans to host Giuliani. . The pledge came after anti-abortion activists gathered outside the Baltimore Archdiocese's offices yesterday and asked Keeler to revoke Loyola's religious status.

Keeler, as local bishop, has that authority.

"The cardinal's very disappointed, but he thinks his actions and the letter he sent to the administration yesterday are sufficient," Caine said.

A Catholic activist group applauded the cardinal's boycott.