THE uproar about sexual assaults on American college campuses is growing louder. Barack Obama has called them “an affront to our basic humanity”. Several universities—including Johns Hopkins, San Diego State, Emory, MIT, Clemson and the University of Virginia—have shut down or suspended parties at their fraternities in recent months. This week Wesleyan University in Connecticut banned a fraternity from holding social events for a year following two allegations of assaults at booze-fuelled revels. Meanwhile, 90 schools in 35 states are under investigation by the federal Department of Education for mishandling cases of sexual violence. Rape and sexual assault in America have declined sharply since the mid-1990s, to 1.1 per 1,000 women per year (see chart). And students are no more likely to be assaulted than non-students of the same age, according to the Bureau of Justice Statistics (though its numbers are somewhat out of date). Yet activists insist that American campuses—and especially fraternities—nurture a “rape culture”.

They often cite an estimate that one woman in five will be sexually assaulted during her time in college, which comes from a report prepared for the Justice Department in 2007. Sceptics doubt this estimate, noting that it was based on a small sample (an online survey of two universities) and used a broad definition of sexual assault, which included everything from rape to any kind of “unwanted sexual contact”, as well as any encounter where one party was too intoxicated by alcohol or drugs to give informed consent.

Reports of horrific individual cases have brought extra attention to the issue.

Rolling Stone

recently published an account of an alleged gang-rape at the University of Virginia, where a student says she was attacked by seven men while lying on shards of a broken glass-topped table. The magazine appears not to have interviewed the (un-named) alleged perpetrators, so it is unclear how they respond to the charges*.

In 2011 the Department of Education sent colleges a letter warning that if they did not take steps to curtail sexual violence, they could be in violation of Title IX, a federal anti-discrimination law. It urged schools to set up committees to adjudicate complaints of sexual wrongdoing, even of heinous crimes such as rape. These committees often consist of untrained professors, administrators and students. The director of a campus bookstore served on a judgment panel for one college last year.

Under this system, defendants and victims have no right to legal counsel and no opportunity to cross-examine witnesses. Colleges typically determine guilt based on the civil “preponderance of the evidence” standard, meaning it is more likely than not that the perpetrator committed the crime, rather than the far tougher “beyond a reasonable doubt” standard, which is used in criminal courts. Panels cannot jail wrongdoers, but they can expel them.

Students on both sides of the fence have complained that these amateur tribunals are inept. A lawsuit this year alleged that Columbia University unfairly allowed perpetrators to remain on campus. Meanwhile male students at Vassar, Duke, and the University of Michigan have sued their schools, claiming that campus committees found them guilty of sexual misconduct when they were innocent. At Harvard 28 law professors recently criticised the university’s new sexual-assault procedures as lacking “the most basic elements of fairness and due process”.

Critics of the system argue that crimes should be dealt with by the police and the courts. In colleges as in the wider world, most rape victims never report the attack to the police. Studies suggest that the vast majority of campus assaults are committed by a small fraction of college men who tend to rape over and over again. So campuses would be safer if these habitual offenders were swiftly identified and arrested, rather than just expelled—leaving them free to go to another college and rape again.

Other critics think that colleges—and the government—should regulate alcohol more realistically. Binge-drinking is common on campuses, and cited in many complaints of sexual transgressions. But because students under 21 have no legal way to obtain alcohol, they tend to party in places where there is no adult supervision nearby, such as in fraternity houses, which are not technically part of the university. The head of the University of Virginia notes that students at frat parties often have no idea how strong their drinks are. (At some parties, the hosts mix everything up in a trash can.)

The lack of adult supervision has had dire consequences: men in fraternities are three times more likely to rape than other men on campus, according to John Foubert of Oklahoma State University. If the drinking age were lowered, parties could be held on campus and colleges could supervise them better, critics say.

* On December 5th Will Dana, the managing editor of Rolling Stone, issued a note to readers saying that the gang rape story they published may have been inaccurate.