Now consider that one large survey showed that around 40 percent of undergraduates, both men and women, had sex while under the influence of alcohol. Are all these students rape victims? And what if both parties were under the influence? Asked this question, a Duke University dean answered, “Assuming it is a male and female, it is the responsibility in the case of the male to gain consent.” This answer shows more ideology than logic.

In fact, sex with someone under the influence is not automatically rape. That misleading statement misrepresents both the law and universities’ official policies. The general rule is that sex with someone incapacitated by alcohol or other drugs is rape. There is — or at least used to be — a big difference. Incapacitation typically means you no longer know what’s happening around you or can’t manage basic physical activity like walking or standing.

So where is this misleading statement coming from? It’s part of the revolution in sexual attitudes and college sex codes that has taken place over the last 50 years. Not long ago, nonmarital sex on college campuses was flatly suppressed. Sex could be punished with suspension or expulsion. This regime kept universities out of the business of adjudicating rape charges. Rape was a matter for the police, not the university.

Beginning in the late 1960s however, sex on campus increasingly came to be permitted. Only nonconsensual sex was prohibited. The problem then became how to define consent.

According to an idealized concept of sexual autonomy, which has substantial traction on college campuses today, sex is truly and freely chosen only when an individual unambiguously desires it under conditions free of coercive pressures, intoxication and power imbalances. In the most extreme version of this view, many acts of seemingly consensual sex are actually rape. Catharine A. MacKinnon took this position in 1983 when she argued that rape and ordinary sexual intercourse were “difficult to distinguish” under conditions of “male dominance.”

Today’s college sex policies are nowhere near so extreme, but they are motivated by a similar ideal of sexual autonomy. You see this ideal in play when universities tell their female students that if they say yes under the influence of alcohol, it’s still rape. You see it in Duke’s 2009 regulations, under which sex could be deemed coercive if there were “power differentials” between the students, “real or perceived.” You also see it in the new “affirmative” sexual consent standards, like the one recently mandated in California, or in Yale’s new policy, according to which sexual assault includes any sexual contact to which someone has not given “positive,” “specific” and “unambiguous” consent.

Under this definition, a person who voluntarily gets undressed, gets into bed and has sex with someone, without clearly communicating either yes or no, can later say — correctly — that he or she was raped. This is not a law school hypothetical. The unambiguous consent standard requires this conclusion.