Four avenues have been proposed to protect free speech on campus. Only one will work: discourage donations to schools that refuse to implement the First Amendment.

Avenue one: mandate free speech on campus. Most faculty would pay attention to this edict, but many students wouldn’t. Their continuing disruptions in auditoriums would impede or stop lectures. These student disruptors could be expelled from school for the semester, but I don’t see administrators now doing this.

Avenue two: inform students that so-called hate and even racist speech on public campuses is protected by the First Amendment. Most students, we learn from polls, do not believe that hate speech is protected. But if a public school takes government money, it is required to comply with the First Amendment. The U.S. Supreme Court has said this often.

The late Justice Antonin Scalia stated, “If you stop speech that hurts other peoples’ feelings, the First Amendment will become a dead letter.” Similarly, when Samuel Alito was an appellate judge, he opined: “There is no ‘harassment exception’ in the First Amendment’s free speech clause.”

The Supreme Court decision in Matal v. Tam held that “viewpoint discrimination”—against insensitive viewpoints—is unconstitutional. And in Terminiello v. Chicago, Justice William O. Douglas wrote in the majority opinion, “The function of free speech under our system of government is to invite dispute.... Speech is often provocative.”

But most college students—and even some faculty members and administrators—don’t know about these Supreme Court decisions and still believe that hate speech can be suppressed. Even the “N”-word is protected. But it is a moral, not legal, matter for these protestors.

Avenue three: to have wider intellectual diversity, require universities to hire more center-right professors. Professors, we know from endless polls, are predominantly left-leaning. But more right-leaning professors can’t be hired because administrators can’t ask applicants, “What is your political persuasion?” That would be inappropriate and probably illegal. Professors are hired to be professors, not politicians. Nevertheless, I still subscribe to John Stuart Mill’s position that “he who knows only his own side of the case knows little of that.” Open, honest debate on campus is intellectually and morally healthy.

Avenue four: Take or keep some money from universities. This, to be sure, would get their attention. President Trump is considering denying federal research funds to universities that fail to protect free speech. I personally believe this is too punitive. Similarly, withholding Pell grants would be too punitive to both students and universities.

So what funds could be kept from universities for not enforcing free speech? The following proposal would force many, if not most, universities to do something about student protestors: deny federal tax exemption for donations to schools that don’t protect free speech. Such donations are now generally untaxed. If schools did not enforce the First Amendment, they would do so at their own peril because donors might give less if they get no tax deduction. But there would be an easy way for them to keep their full donations: follow the law.