About 300 Catholic University students, many sporting bright yellow "Eleanor Smeal Day" buttons, cheered and applauded the feminist leader who addressed them last night at the Capital Hilton after she was barred from appearing at the school because of her support for legalized abortion.

Smeal, president of the National Organization for Women, clearly had the vast majority of the audience with her as she assailed the Catholic Church's opposition to birth control, abortion and sex education and the inequality of women in the church.

Noting that she had spoken without incident on other Catholic campuses, including the University of Notre Dame, Smeal said, "I feel [Catholic] University is making a tragic error. I feel the hierarchy is making a tragic error, for there are no walls high enough to ban a new idea," the concept of feminism.

Feminists "are everywhere," she said, adding that "a disproportionate number of feminists come from a Catholic heritage . . . . That's why I think the church wants to ban us. We are in the majority everywhere . . . including in Catholic lay thought."

When Smeal's scheduled appearance on the campus late last month was canceled, allegedly because of pressure from undergraduate antiabortion organizations, law students invited her to speak at the law school.

But after more than a month of negotiations, permission was not forthcoming from the administration, said John Gilmore, an officer of the campus chapter of the National Lawyers Guild, who was chairman of last night's session.

Faulting university administration for refusing permission to hold the lecture on campus, Gilmore said, "Our reward for trying to comply with all the regulations was betrayal."

The controversy has raised serious questions about academic freedom at CU, Gilmore said, adding that the Lawyers Guild and seven other law school student organizations were gathering signatures petitioning CU President William J. Byron to participate in a "campus-wide symposium" on academic freedom at the school.

"We can't sanction the return of medieval times," he said. "Academic freedom on campus must be preserved."

Smeal, who was brought up as a Catholic, told in emotional detail about her break with church teaching banning birth control. Suffering from Mediterranean anemia, she said her health was so impaired by her second pregnancy that she was bedridden for a year afterward.

"My husband and I decided we wouldn't risk a third pregnancy," she said, nor were they willing to "live as brother and sister," as she said her parish priest counseled her.

"I think this is a profoundly personal issue . . . . I think this is an issue the government and the church can't decide for all people."

When John Paul II, in his African tour last summer, condemned the use of birth control, Smeal said, "that was not the position of a compassionate man."

Smeal spoke for more than an hour, ending with an emotional appeal. "You are educated," she said to the students, about equally divided between men and women. "You are from a belief system that is very powerful in our society. You have a voice . . . . I hope it will be used."

Only a few students remained resolutely seated during the standing ovation that followed.