Northwestern University professor Laura Kipnis didn’t set out to become a martyr to free speech when she wrote a spirited essay in The Chronicle of Higher Education pushing back against “sexual paranoia” on college campuses.

To stir the pot, yes. But not to make an example of herself in the fight against the stultifying regime of political correctness that grips academia.

This is the chilling fact at the center of the Kipnis affair: Her university investigated her for something she wrote, and not even something that was remotely anti-feminist or traditionalist.

No one will mistake Kipnis, who teaches filmmaking, for Phyllis Schlafly. Publishers Weekly gushed that an evidently pro-adultery book she wrote combined “the slashing sexual contrarianism of Mailer” and “the scathing antidomestic wit of early Roseanne Barr” (sounds delightful).

This gets to another fact that should be chilling for liberals blase about the Jacobin campus atmosphere: If they can come after Kipnis, they can come after anyone.

Conservatives in academia have long traded stories of fear on campus, of keeping their heads down lest they get harassed or fired. Now, the illiberalism of the left is being turned against its own.

The groves of academe have become grim prosecutorial arenas where everything you say can and will be used against you. The potential McCarthyites sit in every lecture hall and seminar room, and they are children of the left, students who have been trained and encouraged to be whiny, litigious and censorious.

This is a dystopia of the left’s making. Its identity politics, feminism and hysteria about campus rape are ascendant on campus. On top of this, it is the Obama administration that weaponized Title IX in response to the alleged epidemic of campus rape and made it a clear and present danger to due process and freedom of expression.

In her essay, Kipnis argued that “in the post-Title IX landscape, sexual panic rules,” and the new campus codes are “intellectually embarrassing.”

Her critics could have argued back and hoped one day to be able to write as well as she does. Instead, they protested Kipnis (carrying mattresses, naturally) and reported her to the authorities.

In retrospect, Kipnis might as well have been a 13th-century monk taunting the Inquisition. She was duly accused of violating Title IX by writing an essay questioning the excesses of Title IX.

The university’s investigation of her was about what you would expect if Kafka’s Josef K. had provoked the shadowy Committee of Affairs by writing an uncongenial op-ed. It was difficult for Kipnis even to find out what she was accused of, which turned out to be violating a Title IX prohibition against retaliating against an accuser — even though all she did was write about a case that had nothing to do with her.

Kipnis was eventually cleared, but the process was the punishment. Her experience has caused liberal soul-searching. It’s all fun and games when, say, feminist-critic Christina Hoff Sommers gets protested, but when a film professor with high regard for Foucault is targeted, then clearly things have gotten out of hand.

If liberals are going to push back against the politically correct regime, they will have to do presumably unwelcome things: insist that students not treat speech they disagree with like a physical threat; acknowledge that campus rape, even if a serious issue, is not an out-of-control plague that requires dispensing with due process and other norms; and pressure the Obama administration to rescind its notorious April 2011 letter on Title IX that has roiled campuses and caught up innocent actors like Kipnis.

In its statement on her case, the campus free-speech group FIRE wrote, “The transmogrification of Title IX into an all-purpose excuse for knee-jerk overreactions to complaints about speech — sometimes only tangentially related to sex — is an unacceptable trend that endangers freedom of expression and undermines the purpose of higher education.”

Laura Kipnis just proved it.

Rich Lowry is a syndicated columnist. He can be reached via e-mail at: comments.lowry@nationalreview.com .