The international controversy surrounding the printing of cartoons depicting the Prophet Mohammed has been historic in scale: dozens have been killed, riots and protests have taken place all over the world, death threats have been issued against the cartoonists and some newspapers have openly admitted that they will not publish the cartoons for fear of violent reprisal. It was only a matter of time before a controversy of such magnitude reached America's college campuses. In recent weeks, students, professors and student publications have not only reprinted the controversial cartoons, but even created their own satirical cartoons depicting Mohammed.

Despite all the fear and confusion surrounding these cartoons, there can be no question that they constitute protected speech — legally speaking, this is not a close call. The First Amendment does not tolerate censorship merely because an image might be offensive to some viewers. The Supreme Court showed great prescience in 1949, when it wrote in Terminiello v. Chicago that free speech "may indeed best serve its high purpose when it induces a condition of unrest, creates dissatisfaction with conditions as they are, or even stirs people to anger. … There is no room under our Constitution for a more restrictive view."

One "exception" to the First Amendment that has emerged as a possible rationale for censoring the cartoons is that they may constitute an "incitement to violence." This argument, however, misunderstands the nature of "incitement." Legally defined, "incitement," happens when a speaker encourages imminent lawless action in a context where it is likely to take place immediately. For example, a speaker exhorting an angry, violent crowd to attack a government office could be found guilty of incitement. However, if a speaker's words result in violence because people despise what that speaker said and wish to silence him or her, that is a different matter entirely. Telling a speaker that he or she cannot speak because it might provoke an angry mob to violence is called granting a "heckler's veto." If society punished people on the basis of how harshly others might react to their words, it would create an incentive for those who disagree to react violently. This would therefore confer a veto on speech to the least tolerant members of society. Lest we embark upon a downward spiral to mob rule, it is extremely dangerous to all of our freedoms to ever grant a heckler's veto.

The Foundation for Individual Rights in Education understands that the fear of violence is powerful, but such a fear must not lead universities to forget that their primary duty is to defend the rights of students and faculty to hold and express their opinions and to promote the perpetual search for truth, not to placate those who would silence them. The First Amendment confers upon authorities both a "positive" and "negative" duty: a "negative" duty not to censor, as well as a "positive" duty to protect speakers from being silenced by the mob. This second aspect of free speech may be the hardest element to implement, but without it, the crudest forms of tyranny could result.

In 1943, when the United States' success in the battle against totalitarianism was far from certain, the U.S. Supreme Court upheld the highest principles of a free society in West Virginia State Board of Education v. Barnette. As Justice Robert Jackson so eloquently wrote:

"Freedom to differ is not limited to things that do not matter much. That would be a mere shadow of freedom. The test of its substance is the right to differ as to things that touch the heart of the existing order. If there is any fixed star in our constitutional constellation, it is that no official, high or petty, can prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion or force citizens to confess by word or act their faith therein. If there are any circumstances which permit an exception, they do not now occur to us."

These brave words should remind us that the battle for free speech is often a deadly serious one. The campus free speech debates of the last two decades may give one the false impression that those debates have primarily revolved around issues like politeness, sensitivity or hurt feelings. But if one looks at the great free speech debates of American history, one discovers that often the concerns of the censors were quite real and serious: they feared riots, bloodshed, threats to global or national security, and even civil war. Even under these fearsome circumstances, American society has time and time again chosen liberty and sunlight over repression. Free speech has not been an easy path, but it is one worth following. Living with liberty often requires courage, but when this most sacred of American principles is threatened, we always seem to find the courage to defend it.

Greg Lukianoff is an attorney and the interim president of the Foundation for Individual Rights in Education.