Mike: "Kittredge, it may interest you to know that the so-called 'affair' consisted of exactly two kisses and a rather late swim …"

Tracy: "Why? Was I so unattractive, so distant, so forbidding … ?"

Mike: "You were extremely attractive. And as for distant and forbidding, on the contrary! But you also were a little the worse — or the better — for wine, and there are rules about that."

In Hollywood's classic 1940 comedy of manners, "The Philadelphia Story," Jimmy Stewart earned an Oscar playing Mike Connor, a hard-boiled magazine reporter who helps socialite Tracy Lord (Katherine Hepburn) shed her icy, elitist reserve.

The quaint story's climax comes the morning after their tipsy swim, when Mike reveals — not least to an almost disappointed Tracy, who doesn't remember a thing — that nothing untoward came of their starlit rendezvous.

And why? Because she was drunk, and in those primitive times there were "rules about that."

Jimmy Stewart and Katherine Hepburn in a scene from “The Philadelphia Story.”

This evidence excavated from Hollywood's golden age sheds flickering light on the continuing and intensifying controversy about how to restore order to what is reportedly something like sexual anarchy on America's college campuses.

Responding to growing alarms about what's described as an epidemic of sexual assault against college women, schools and legislatures across the country are imposing or considering a new disciplinary standard for sexual conduct called "affirmative consent."

California naturally has adopted the trailblazing law. It basically means that a guy could be in trouble unless the woman he had sexual contact with at last night's frat party explicitly — and repeatedly — consented to it. And it's no excuse, the law says, for him to claim he thought she consented if he knew she was drunk.

In short, it's the Jimmy Stewart rule, translated into legalistic language and thoroughly updated. ("It is the responsibility of each person involved in the sexual activity," California's legislation reads, "to ensure that he or she has the affirmative consent of the other or others.")

It's tempting to wonder whether today's college mixers need not chaperones but federal mediators to hammer out multilateral agreements. (The sexual activity approved herein shall include, but not be limited to, etc., etc. — and especially etc.)

Some prominent conservative pundits are ridiculing the whole idea of an epidemic of "sexual assault," the definition of which has been ludicrously overextended, they say. It's true that the affirmative-consent standard itself seems aimed at what might better be called "taking advantage." But an epidemic of that seems lamentable enough.

Meanwhile, affirmative-consent policies are inspiring an agonized debate among liberal commentators like Ezra Klein, Jonathan Chait, a phalanx of Harvard law professors and more. Many are concerned that "illiberalism" is triumphing within progressive academe in response to the sexual-misconduct crisis — that due process and the presumption of innocence can't survive under such a standard. Others see an attack on women's sexual liberation as they are returned to their pedestal and defined anew as helpless to assert their own wishes.

Klein has stirred a lot of reaction with his Vox.com commentary admitting all the flaws of affirmative consent but insisting that the new regime is still much needed "to create a world where men are afraid."

Here again, this sounds less like creating an enlightened new world than like recovering part of a world that once was — a world whose waning days people my age are just old enough to remember. A world with "rules about that."

And of course the "that" surrounded by rules in olden times was nonmarital sex in general — not just drunken sex or even just nonconsensual sex.

The sexual revolution, which my 1960s generation did so much to foment, brought many good things. It has freed female sexuality and contributed to women's broader social emancipation. And it has brought much enjoyment, not least by allowing a candor and comradeship between the genders that was difficult before.

But the apparently unhappy sexual scene on campus today looks a bit like the kind of consequence baby boomers' parents and grandparents warned us would result if sex were too far deregulated. They had a crazy conviction that men and women aren't exactly the same, and never will be, where sex is concerned.

Their generation knew, after all, how often Hollywood airbrushed their world. There were "rules about that," yes, but those rules frequently got broken.

There's not much danger that we'll go back to post-Victorian sexual mores. Is it possible to return just partway? Could formal regulations replace a few lost and lamented cultural norms — like the Jimmy Stewart rule?

Well, we may have to try. Because Klein is right to suppose that "fear" has always been key to containing male sexual behavior. And relaxed "rules" weren't the only thing that took such fear away. I remember a bit of subversive, holiday-themed doggerel from my youth celebrating another rather big change:

God rest ye Merry Gentlemen,

Let nothing you dismay,

For liking sexual intercourse,

No consequence you'll pay,

Science has the answer now,

The pill will save the day.

Oh, tidings of comfort and joy …

But some tidings, it seems, have turned out more complicated than that.

D.J. Tice is at Doug.Tice@startribune.com.