GREENBELT, Md. — The University of Maryland's policy of limiting public speakers and leafleting to two specific campus locations violates the right of its students to free expression, according to a lawsuit filed by the American Civil Liberties Union.

The college says the "free-speech zones" are a way to reduce litter and preserve order. But some students claim the restrictions squelch free speech.

"When you come to college, you want to hear other viewpoints," said plaintiff Dan Sinclair, a junior from Baltimore. "I was expecting to hear free and impassioned debate, I expected to have the campus buzzing."

The suit, filed yesterday in U.S. District Court in Greenbelt, is the latest challenge to free-speech zones at colleges across the country.

West Virginia abolished its zones last year after students were barred from handing out anti-sweatshop leaflets outside a campus corporate recruiting event. Zones at the University of Texas and New Mexico State University have also been dropped because of similar challenges.

University spokesman George Cathcart says the school believes its policies are fair.

"We're not aware of anyone who feels that their ability to speak out on campus has been impaired by our policies," Cathcart said.

Maryland's policy, which has been in effect for decades, limits public speaking to the Nyumburu Amphitheater stage. Leafleting is limited to the sidewalks outside Stamp Student Union. Both require reservations, the lawsuit states.

The ACLU has tried for several years without success to get the university to change its policy, said David Rocah, an attorney with the group.

"There is no legitimate justification for rules like this," Rocah said.