Last week, several members of the newly formed Youth for Western Civilization invited Tom Tancredo to the University of North Carolina-Chapel Hill to speak against permitting undocumented immigrants to enter state community colleges on the same basis as other North Carolina high school graduates. Former Congressman Tancredo was invited because of his well-known nativist views against immigration.

A hostile crowd of protesters thwarted his speech with catcalls and placards. Someone threw a rock and smashed a window. Campus police cleared the protesters with pepper spray. Tancredo quietly slipped away.

And earlier this week, a panel discussed the legal implications of racist graffiti in the Free Speech Tunnel at N.C. State University, including one epithet that announced on Election Night 2008 that President Barack Obama should be shot.

These events have raised several questions: What is the line between hate speech and free speech? And how should we responsibly and effectively protest against views we roundly despise?

First, the rowdy protest at UNC is not the Carolina way. Ours is a history of participation in current events through civil discourse with all manner of controversial speakers—and peaceful protests.

I learned of this history when in 1957 I refused to sign a "loyalty oath" and lost my job teaching law at the University of Arkansas. This made me suspect in the Cold War era of Joe McCarthy and I feared my academic career was over. But possibly because of my principled stance, I was offered jobs at UNC, Missouri and Pennsylvania. I chose UNC.

Students invite whomever they choose to hear, and we even provide a safe haven for those shunned elsewhere. When Martin Luther King Jr. was in his early bitterly controversial march for equality, the student group at the University Baptist Church invited him to speak at evening Vespers. On the appointed day, church elders revoked the invitation. The Rev. King was immediately invited to give his speech at UNC. He gave a provocative, but thoughtful, talk across from the church to a packed audience in Hill Hall.

Malcolm X came to UNC under similar circumstances. Authorities at N.C. Central University cancelled a scheduled speech at the last moment. Durham Mayor Evans invited him to speak at a city auditorium, but City Council met and subsequently overruled him. WRAL announced these fast moving events, and that Malcolm X had put a curse on the city.

Malcolm X was invited to UNC with his message, and except for the first question ("Please show us how you put a curse on Durham"), there was a no-holds-barred, spirited but friendly conversation with the overflow audience.

Prominent Ku Kluxer David Duke spoke here; silent protesters lining the walls and the back of the stage at Memorial Hall sent a far louder message than anything Duke could say.

Yet such free speech on campus has not always been welcome—or legal. In 1963, the state legislature enacted the Speaker Ban Law, banning known Communists and other subversives from speaking on the campus.

In response, UNC Student Body President Paul Dickson, joined by other student leaders, invited known Communist Herbert Aptheker and free speech activist Frank Wilkinson to speak on campus. UNC Chancellor J. Carlyle Sitterson, citing the Speaker Ban laws, cancelled the invitation. Aptheker and Wilkinson came anyway. Unable to speak on the campus, they stood on the Franklin Street sidewalk bordering UNC and spoke over a small stone wall to a large crowd of students.

Dickson and other student leaders sued Sitterson and N.C. Gov. Dan K. Moore (he was charged with enforcing the law), claiming the ban violated Aptheker's right to speak under the First Amendment—and their right to listen. A three-judge federal court ruled for the students; Sitterson did not appeal.

When the Speaker Ban ended, peaceful protests continued. For example, when the UNC Law School invited right-wing Supreme Court Justice Clarence Thomas to speak, some faculty arranged a "teach-in" to fully discuss Thomas' opinions and public life, to inform the public about his philosophy.

On another occasion, students picketed outside the law school office where military recruiters were interviewing prospective soldiers. Students wanted UNC to prohibit recruitment on campus by employers who discriminate against homosexuals—comparable to UNC's ban on recruitment by employers who discriminate on the basis of race, religion or gender. The protest was peaceful, but the interviewers moved the interviews off-campus to their motel.

Apart from controversial speakers, students protested UNC investments in companies conducting business with apartheid South Africa by erecting a "shanty village" on the campus. And recently, to protest homelessness students spent the night at the Pit sleeping in cardboard boxes.

To protest what Tancredo had to say (not his saying it), students held a Dance Party for Diversity in the Pit. This, not the smashed window and pepper spray, is what makes Carolina so appealing.

Now what about N.C. State University's Free Speech Tunnel and the childish hate scrawl threatening to kill President Obama? First, the constitutional right of free expression is powerful medicine, and under that founding document, we have a "profound national commitment" that debate on public issues should be "uninhibited, robust, and wide open."

It may well include vehement, caustic and unpleasantly sharp attacks on government and public officials. Even false and misleading statements must be protected "if the freedoms of expression have the breathing space they need to survive," the Supreme Court has ruled.

In a later decision, the Court went further in holding that what it called a "scurrilous epithet" (the man was arrested for wearing a jacket with the slogan "Fuck the Draft") cannot be "excised from the public discourse because much linguistic expression is chosen as much for their emotive as their cognitive force."

Billboards may urge "Impeach Earl Warren" or "Welcome to Klan Country," or an anti-abortion sign may display ruptured fetuses. They may offend some travelers but are equally protected. So too, some may salute the flag, others may burn it, still others may fold it into a bikini. Again, in our disputatious society, all are protected.

Of course, there are limits. Courts have ruled one can't use "fighting words"—those "likely to cause an average addressee to fight." If the offending words come from afar, they probably pass constitutional muster. And government may regulate the time, place or manner of the speech.

In this case, the Free Speech Tunnel seems to have few limitations. While threatening to kill the U.S. president is a serious federal crime, it must be a "true threat," holds the Supreme Court. An 18-year-old at an anti-Vietnam War rally at the Washington Mall once said, "If they ever make me carry a rifle, the first man I want to get in my sights is L.B.J." The Supreme Court held that this was not a "true threat" but "political hyperbole," a "kind of very crude offensive method of stating a political opposition to the President."

When President Ronald Reagan was shot in 1981, a Texas deputy constable was fired when she told a co-worker, "Shoot, if they go for him again, I hope they get him." The Supreme Court ordered her reinstated because her words must be weighed against the consideration of our First Amendment heritage: that public debate must be free and uninhibited, including sharp attacks on public officials. The same could be said of the threats in the tunnel.

In a case about the right of students to demonstrate, the court wrote that any word that deviates from the views of another may cause a disturbance, but "Our Constitution says we must take this risk, and our history says that it is this sort of hazardous freedom—this kind of openness—that is the basis of our national strength, and of the independence and vigor of Americans who grow up and live in this relatively permissive, and often disputatious society."

So let it be.

Disclosure: Professor Dan Pollitt was one of the three lawyers representing the students in the Speaker Ban case.