At the University of North Carolina, three incoming freshmen sue over a reading assignment they say offends their Christian beliefs.
In Colorado and Indiana, a national conservative group publicizes student charges of left-wing bias by professors. Faculty get hate mail and are pictured in mock "wanted" posters; at least one college says a teacher received a death threat.
And at Columbia University in New York, a documentary film charging that teachers intimidate students who support Israel draws the attention of administrators.
The three episodes differ in important ways, but all touch on an issue of growing prominence on college campuses.
Traditionally, clashes over academic freedom have pitted politicians or administrators against instructors who wanted to express their opinions and teach as they saw fit. But increasingly, it is students who are invoking academic freedom, claiming biased professors are violating their right to a classroom free from indoctrination.
In many ways, the trend echoes past campus conflicts -- but turns them around. Once, it was liberal campus activists who cited the importance of "diversity" in pressing their agendas for curriculum change. Now, conservatives have adopted much of the same language in calling for a greater openness to their viewpoints.
Similarly, academic-freedom guidelines have traditionally been cited to protect left-leaning students from punishment for disagreeing with teachers about such issues as American neutrality before World War II and U.S. involvement in Vietnam. Now, those same guidelines are being invoked by conservative students who support the war in Iraq.
To many professors, there's a new and deeply troubling aspect to this latest chapter in the debate over academic freedom: students trying to dictate what they don't want to be taught.
"Even the most contentious or disaffected of students in the '60s or early '70s never really pressed this kind of issue," said Robert O'Neil, former president of the University of Virginia and now director of the Thomas Jefferson Center for the Protection of Free Expression.
Those behind the trend call it an antidote to the overwhelming liberal dominance of university faculties. But many educators, while agreeing students should never feel bullied, worry that they just want to avoid exposure to ideas that challenge their core beliefs -- an essential part of education.
Some also fear teachers will shy away from sensitive topics, or fend off criticism by "balancing" their syllabuses with opposing viewpoints, even if they represent inferior scholarship.
"Faculty retrench. They are less willing to discuss contemporary problems and I think everyone loses out," said Joe Losco, a professor of political science at Ball State University in Indiana who has supported two colleagues targeted over accusations of bias. "It puts a chill in the air."
Conservatives say a chill is in order.
A recent study by Santa Clara University researcher Daniel Klein estimated that among social science and humanities faculty members nationwide, Democrats outnumber Republicans by at least seven to one. In some fields, it's as high as 30 to one. And in the last election, the two employers whose workers contributed the most to the presidential campaign of Sen. John Kerry, Massachusetts Democrat, were the University of California system and Harvard University.
Many teachers insist personal politics don't affect teaching. But in a recent survey of students at 50 top schools by the American Council of Trustees and Alumni, a group that has argued there is too little intellectual diversity on campuses, 49 percent reported at least some professors frequently commented on politics in class even if it was outside the subject matter.
Thirty-one percent said they felt there were some courses in which they needed to agree with a professor's political or social views to get a good grade.
Leading the movement is the group Students for Academic Freedom, with chapters on 135 campuses and close ties to David Horowitz -- a Marxist radical activist as a college student in the '60s, but now a prominent conservative commentator. The group posts student complaints on its Web site about reputed episodes of grading bias and unbalanced, anti-American propaganda by professors -- often in classes, such as literature, in which it's off-topic.
Instructors "need to make students aware of the spectrum of scholarly opinion," Mr. Horowitz said. "You can't get a good education if you're only getting half the story."
Conservatives claim they are discouraged from expressing their views in class, and are even blackballed from graduate school slots and jobs.
"I feel like [faculty] are so disconnected from students that they do these things and they can just get away with them," said Kris Wampler, who recently publicly identified himself as one of the students who sued the University of North Carolina. Now a junior, he objected when all incoming students were assigned to read a book about the Koran before they got to campus.
"A lot of students feel like they're being discriminated against," he said.
So far, his and other efforts are having mixed results. At UNC, the students lost their legal case, but the university no longer uses the word "required" in describing the reading program for incoming students [the plaintiffs' main objection].
At Columbia, anguished debate followed the screening of a film by an advocacy group called the David Project that accuses some faculty of violating students' rights by using the classroom as a platform for anti-Israeli political propaganda. (One Israeli student claims a professor taunted him by asking, "How many Palestinians did you kill?") Administrators responded this month by setting up a new committee to investigate students complaints.
In Colorado, conservatives withdrew a legislative proposal for an "academic bill of rights" backed by Mr. Horowitz, but only after state universities agreed to adopt its principles.
At Ball State, the school's provost sided with professor George Wolfe after a student published complaints about Mr. Wolfe's peace studies course, but the episode has attracted local attention. Mr. Horowitz and backers of the academic bill of rights plan to introduce it in the Indiana legislature -- as well as in up to 20 other states.
Ball State senior Brett Mock published a detailed account accusing Mr. Wolfe of anti-Americanism in a peace studies class and of refusing to tolerate the view that the U.S. invasion of Iraq might have been justified. In a telephone interview, Mr. Wolfe vigorously disputed Mr. Mock's accusations.
Mr. Horowitz expressed little sympathy when asked if Mr. Wolfe deserved to get hate e-mails from strangers.
"These people are such sissies," he said. "I get hate mail every single day. What can I do about it? It's called the Internet."