We understand the University of Wyoming's reluctance to discuss litigation against it. Bill Ayers' threat of a lawsuit for not being allowed to speak on campus will likely become a reality this morning when it's filed in federal court in Cheyenne.

But UW has a broader responsibility to explain to the public why it has banned Ayers. This action is much different than what happened earlier this month, when the UW Social Justice Research Center rescinded its invitation to Ayers to speak at a conference on education.

That decision was made by the center's director, Francisco Rios, over security concerns. News that the former radical-turned-education professor was coming to Laramie prompted hundreds of e-mails and phone calls to UW officials expressing outrage that someone with Ayers' past was invited to the university. According to Rios, some people made threats of violence. Others said they would stop donating money to UW.

Meg Lanker, a UW student upset about the cancellation, invited Ayers to UW to lecture. She was joined by the Secular Student Alliance, a UW-recognized student organization. The group booked a Classroom Building room for April 28, but when UW officials learned that Ayers was going to be the speaker, Lanker was notified by UW attorney Susan Weidel that he could not speak anywhere on campus. She did not provide a reason.

David Lane, a Denver attorney representing Ayers and Lanker, gave UW a deadline of "high noon" Wednesday to allow Ayers to speak or face a federal lawsuit for violating his First Amendment right to free speech. While the deadline was overly dramatic, it came and went with no response from the university.

We don't know who would prevail in such litigation, but do take the free speech issue seriously, as should all Wyoming residents. A university should be a place where a diverse range of opinions is encouraged, not restricted. UW has welcomed speakers of all political stripes in the past, from Dick Cheney and Henry Kissinger on the right to Angela Davis and Bobby Seale on the left. As far as we can tell, no one has ever been banned on campus except Bill Ayers. An explanation is needed.

In 1969 Ayers founded the Weather Underground, an anti-war group that set off bombs at the Pentagon and U.S. Capitol that didn't kill anyone. He has never been convicted of a crime, and has been a distinguished professor for many years. His UW talk is scheduled to address education, not his radical past.

To ban Ayers flies in the face of UW President Tom Buchanan's response to those opposed to Cheney's UW appearance last September. He said good universities operate on principle, that tolerance and diversity cut many ways, and everyone is welcome on UW's campus no matter their political or religious beliefs, race or sexual orientation.

"The real danger to institutional integrity comes from persons, on either end of the political spectrum, who would bend us to adopt to their particular perspective and purpose," Buchanan wrote in a Star-Tribune column. "And we simply won't have that."

Absent any explanation, it appears that's what happened in Ayers' case. Do UW officials not give students credit for being able to listen to diverse opinions and make up their own minds?

In a democracy, free speech is a right. Who is allowed to speak isn't decided by the majority or those who donate to an institution or those who have different beliefs. It certainly must not be based on the will of those who threaten violence.

UW has a choice. It can do the right thing and stand up for free speech and academic freedom, or it can cave in to special interests and spend money on a lawsuit to defend a position that denies both.

As Buchanan correctly said, it's a matter of institutional integrity.