Imagine serving on the campus equivalent of a jury in a sexual-assault case.

The accused testifies, "I thought I was reading all the signals right. Once we started kissing it felt like things progressed naturally, like we were both into it. Neither of us said, 'Yes, let's do this,' but I definitely wanted to hook up. I felt sure we both did." The accuser says, "I was totally comfortable when we started kissing, but as things progressed I felt more and more uncomfortable. I didn't say stop or resist, but I didn't consent to being groped or undressed. I wasn't asked. I didn't want that." If both seem to be telling the truth as they perceive it, what's the just outcome?

Last week, I spent some time at UCLA asking students about California's new "affirmative-consent" law. In our conversations, I described the law and asked them whether they supported it or not. I also posted this scenario to them. I was surprised by how common it was for students to express support for the law and then to say a few minutes later that they wouldn't feel comfortable convicting the accused in that example. But there were also students who opposed affirmative-consent laws and later said that they would find the accused guilty.

That conflict fit with a larger theme that ran through my conversations with undergraduates, from freshmen to seniors. Asked about California's law, many supporters focused on how affirmative consent squared with their notion of what campus norms, values, and culture ought to be, rather than its effect on disciplinary cases, which they treated as a tangentially related afterthought. Opponents expressed abstract concerns about unjust convictions and due process, yet some felt that convicting the accused in that hypothetical would be just.

In short, forcing both sides to confront a specific scenario made them see a thornier issue than they'd imagined. And it increased the conflicted feelings of many of those who had no definite position.

Most of the commentary about how affirmative-consent laws might change campus culture has come from people who graduated years if not decades ago. I wondered how students felt, though. Had things changed? What were journalists missing? I was reminded in my conversations with underclassmen how little experience they have to draw on. It takes a moment to register that the youngest students are actually parroting what they perceive to be the conventionally accepted insights on a subject as often as they're expressing insights of their own. They aren't authorities on college culture. They just arrived. They're still figuring it out.

Students like the ones I met are fully capable of grasping affirmative consent in the abstract. But will they apply the concept to real-world situations? Or will they go to a party, end up kissing someone to whom they're attracted, and suddenly feel in their gut that it would be awkward to ask or be asked about, say, breast-touching?

If excited, inexperienced, and self-conscious (or intoxicated), I suspect they won't be thinking about affirmative consent in that moment. It is pretty tough to imagine a world in which the earliest college hookups begin with thoughtful deliberation and confidence, where both parties are empowered agents who feel comfortable explaining exactly what is or isn't desired. Some lucky few will go through their late teens just that way. But many consensual encounters will feature young people whose inexperience manifests in a muddle of nervous excitement, daring, and fear of being in somewhat over one's head. Some will feel terrified at the idea of forthrightly stating exactly what they desire, because to do so is to make oneself more vulnerable, or so it can seem. Alas, campus predators will occasionally exploit this dynamic. A culture of affirmative consent would likely be an improvement. But is there any way to create such a culture?

I spoke to a dozen UCLA freshmen, all of whom went through orientation mere weeks ago, and while I am certain affirmative consent was covered, just half of them recalled it. Some of the others were hazy on what exactly it meant. The standard has long been in place at UCLA. The culture, however, is not in place, nearly everyone agreed. I came away pessimistic about its prospects, though of course I spoke to too few people to form a definitive judgment. How the freshmen behaved in sexual situations had been powerfully shaped by their high-school experiences, values in their families, TV, their expectations of college, and their perceptions of UCLA culture as they entered it—perceptions shaped more by frats, sports teams, and dorm life than by orientation. Watching these sponges as they soaked up the schizophrenic ethos of a gigantic university in the middle of L.A. made me appreciate how gargantuan a task it is to nudge hookup culture in any deliberate direction.

When I wandered to a part of campus with more upperclassmen, that impression softened slightly. Here were people whose experiences at UCLA had changed them significantly in just two or three years. College is uncommonly formative, and norms there have changed radically before. The 21- and 22-year-olds seemed so much older than the 18- and 19-year-olds. Already they were looking back on their own freshman years, able to see the chasm separating initial impressions from realities that took time to discern.