Liberal students attempted to shut down an event at the University of California-Berkeley earlier this month by resorting to one of the worst kinds of censorship tactics: mob violence.

The event featured a discussion between notable people, including Metallica drummer Lars Ulrich. Ulrich's elderly father participated in the forum, as did wealthy entrepreneur Marc Benioff.

Members of the Student Labor Committee, the group that crashed the event, didn't object to these specific speakers. Rather, they have urged a boycott of all speakers until the administration agrees to their demands, which concern the allegedly subpar conditions endured by contract workers on campus.

Ulrich, who hosted the event, went so far as to allow a protester to speak at the beginning of the event. This was not sufficient for the aggrieved. Eventually protesters stormed the stage and even assaulted Benioff. The police were forced to intervene.

In an op-ed for The Daily Californian, shocked members of the UC community described the spectacle as "violence dressed up as protest." According to the op-ed:

This disruption, however, emblemized neither. More than just an attempt to exercise the heckler's veto, this was a planned, violent, bullying act, with the express purpose of destroying a core activity of the campus.

All groups at UC Berkeley have the right to free expression, but none have the right to prevent others from doing likewise, least of all by using violence. The disruption last week was not an example of protest, it was not the exercise of free speech.

The Foundation for Individual Rights in Education's Nico Perrino put it this way:

Nobody has a First Amendment right to engage in mob censorship to shut down a speaker. Assault in any context is a crime—not the kind of expressive conduct the First Amendment protects.

The behavior of the protesters was shameful, censorious, and even dangerous. If would-be visitors to campus—including interesting figures like Ulrich and Benioff—fear for their safety, they will decline invitations to speak. Such an outcome would deprive students of one of the main benefits of attending university in the first place.

Watch video footage of the assault, below.