Middlebury College—ground zero for one of the most sordid censorship episodes of last year, the physical attack on Charles Murray and Alison Stanger—has announced a new policy regarding guest speakers. Proposed events will be evaluated by a Threat Assessment and Management Team; if the team feels that an event attracts an "imminent and credible threat to the community," it could be cancelled.

The policy, described an "interim" measure by campus officials, attracted criticism from at least one prominent alumnus, former White House Press Secretary Ari Fleischer, who wrote on Twitter that Middlebury will "actually legitimize the heckler's veto."

He has a point. If protesters who oppose a certain speaker know that Middlebury will shut down the event if they threaten the community, this gives them an incentive to issue such threats. This is the heckler's veto: giving the hecklers the power to choose whether an event proceeds.

The policy suggests that such measures would only be put in place for "exceptional cases." But what's an exceptional case? The views Murray intended to articulate at Middlebury last year were perfectly conventional. He's no Milo Yiannopoulos—and in fact, he has specifically refused to share a platform with the former Breitbart writer. And yet students resorted to explicit violence to silence him.

"There are some places where the policy leaves open the possibility of censorship and could be improved to diminish that possibility," says Adam Goldstein, a legal fellow at the Foundation for Individual Rights in Education. "The policy says event cancellations may occur when there is an 'imminent and credible threat,' but doesn't specify what they mean by a 'threat.' People may interpret 'threat to the community' differently. Protests aren't a threat justifying suppression of speech, nor is speech offensive to some (or all) of the community a 'threat' that a university can suppress. If Middlebury intends to limit its policy to credible threats of imminent violence, it should say so. A university should make it clear that it will only cancel a speech, if ever, only as an absolute last resort to stop violence."

Goldstein is also concerned that the policy does not explain where the funds for increased security are supposed to come from. If Middlebury intends to pass these costs along to the students who wish to invite a controversial speaker, then officials would be inadvertently chilling speech.

It would be better for Middlebury to explain how it will protect speakers like Murray in the future—and what steps it will take to impress upon students the value of a robust exchange of ideas. Instead they may be enshrining a literal heckler's veto in the campus rules.