Discretion may be the better part of valor, as Falstaff noted in Shakespeare’s “Henry IV, Part 1,” but Ann Coulter’s canceling of her speech last week at the University of California at Berkeley out of very real fear for her own safety and that of those who wanted to hear her is a body blow to academic freedom everywhere.

“It’s a sad day for free speech,” Miss Coulter told The New York Times after canceling the visit.

The failure of liberal editorial pages and “progressive” TV talking heads to stand up for the conservative firebrand’s free-speech rights, despite whatever ideological disagreements they have with her, is just as sad.

The Washington Post, in its masthead, smugly proclaims “Democracy dies in darkness,” but its editorial silence in this matter suggests democracy is more likely to die in broad daylight on a college campus.

The concept of academic freedom has been reduced to a punch line when UC Berkeley, the very incubator of the academic free-speech movement of the 1960s, is now the antithesis thereof.

That irony is lost on those who fancy themselves as “anti-fascists” when they are in fact nothing more than latter-day brownshirts shutting down speech they disagree with “by all means necessary.”

That pet phrase of the militant left is a sanitizing euphemism for mob violence. In February, UC Berkeley students rioted and set fires to prevent a Feb. 1 speech by another flamboyant conservative, Milo Yiannopoulos

“Berkeley, you know, used to be the cradle of free speech,” Bill Maher, host of HBO’s “Real Time,” noted on his April 21 telecast, “And now it’s just the cradle for [expletive] babies.” Mr. Maher, despite being a liberal, describes himself as “a longtime critic of colleges shutting people up,” and Miss Coulter has appeared on his weekly talk show 12 times.

The anti-free-speech intolerance that pervades not just UC Berkeley, but all too many other college campuses these days, needs to be combated, not capitulated to. Otherwise, it will only get worse — if that’s even possible.

That’s why Miss Coulter must proceed with her lawsuit against UC Berkeley, which scheduled then canceled her speech and then rescheduled it at a time of day and in a campus venue that ensured few would actually hear her.

She and the Berkeley College Republicans filed suit April 24 against the university in U.S. District Court in San Francisco.

The lawsuit demands an appropriate and safe venue for her to speak and monetary damages, Miss Coulter said.

The Berkeley College Republicans’ and Miss Coulter’s refusal to take “no” for an answer should serve as a “teachable moment,” as liberals might say, for colleges generally and the anti-free-speech fascists on campus specifically.

Free speech is not only for speech that the leftist bullies approve of and agree with, nor is anything they disagree with ipso facto “hate speech.” They need to be told forcefully that the “tolerance” they claim to champion is a two-way street.

The cancellation of Miss Coulter’s appearance on the Berkeley campus and the threat of leftist violence and vandalism that prompted it could result in academia finally receiving a long-overdue analeptic.

That was hinted at by President Trump on Feb. 2, the day after Mr. Yiannopoulos’ silencing by many of those same censorious thugs at Berkeley.

“If U.C. Berkeley does not allow free speech and practices violence on innocent people with a different point of view — NO FEDERAL FUNDS?” the tweeter-in-chief wrote. [NOTE: upper-casing sic]

Mr. Trump was almost certainly watching last week, because Miss Coulter was among Mr. Trump’s earliest endorsers during the 2016 GOP presidential primary campaign.

The president should direct his education secretary to make good on his threat to withhold federal education funds from UC Berkeley — and the rest of the University of California system, whose president just happens to be Janet Napolitano.

Ms. Napolitano was Homeland Security secretary in the Obama administration, but apparently she’s either unwilling or unable to ensure security on campus for speakers who don’t toe the far-left line.

The 10-campus University of California system receives more than $2 billion in federal research funding, as well as $1.6 billion in federal student aid, according to its 2015-16 budget summary, the San Jose Mercury News reported.

Withholding even some of those funds would send an unmistakable message to colleges and universities nationwide that are complicit in allowing conservatives to be treated as second-class citizens of the campus community.

The governors of states where campus free-speech rights are being abridged by the brownshirted bullies should do likewise.

Conservative speakers silenced by leftist mobs have traditionally just grumbled and gone home, but the time for “tut-tutting” and “tsk-tsking” at the mob violence is long past. Hit these schools where it hurts.

Peter Parisi is a freelance writer-editor based in Northern Virginia. He was a writer and editor for The Washington Times for 17 years.