Most controversially, OCR said colleges must judge Title IX cases under a standard of "preponderance of evidence." That standard, common in civil law cases, means schools must conclude only that there is a 50.1 percent chance the accused is guilty to find him responsible.
Courts have long granted colleges leeway to use lower standards of proof because they are conducting educational proceedings, enforcing college rules, not criminal laws. And in fact, even before the recent guidance, most colleges were already using the standard of "preponderance" to judge sexual assault cases.
Without the preponderance standard, it can be difficult for colleges to remove rapists.
"To get to proof beyond a reasonable doubt, which is the criminal standard, when you have two people who did something behind closed doors where there were no eyewitnesses and probably a lot of alcohol, it's incredibly hard to prove," said Brett Sokolow, managing partner of the National Center for Higher Education Risk Management, which advises colleges on Title IX.
Still, until recently, roughly 20-30 percent of colleges, including most elite institutions, maintained a higher burden of proof. Typically they required "clear and convincing" evidence to convict, a standard they felt better protected the rights of the accused.
The OCR letter prompted virtually all such colleges to scrap that standard and change to preponderance. In one case, at Stanford University, sexual assault proceedings were already underway against a student under a higher standard when the letter came down. Stanford concluded it had to apply preponderance and switched midway through the proceedings. The student was found responsible.
Civil liberties groups, as well as the AAUP, the country's main faculty union, are alarmed at what they consider a quasi-criminal proceeding that lacks constitutional protections.
Other than a college campus, "there is no other place in America where a body can determine you're guilty of rape, particularly a body that is run by the government, based on a more-likely-than-not standard," said Robert Shibley, an attorney with FIRE, the Foundation for Individual Rights in Education.
Hans Bader, an attorney who worked at OCR under the Bush administration, says OCR's guidelines "stack the deck against the accused." He and other critics contend that OCR is misreading the law. They argue preponderance is an appropriate standard for determining if a college has violated Title IX. But for an individual student, a higher standard should be required — or at least allowed.
"You're talking about effectively convicting somebody and saying they're a rapist," said Shibley, who notes such a charge is potentially life-altering now that colleges, reluctant to pass problem students on to other schools, are increasingly affixing disciplinary notes to the transcripts of students they expel, rather than simply letting them walk away. "You take a really huge stigma with you your entire life."
The preponderance standard amounts "to a 50-50 guess on credibility," he said. "There's a reason we don't run our real courts that way, because you can do so much damage to somebody."
Sherry Warner-Seefeld, Caleb Warner's mother, says she can understand how those hearing the case, faced with irreconcilable stories and a tearful complainant, might have sided with the accuser's version of events. "It's pretty easy to get to 50.1 percent surety in your mind that something might have happened," she said
But she cannot understand why the process had to be rushed, or how such a guess could be solid enough to devastate her son's life. She was worried if he were convicted on campus, a criminal case would follow.
"I went to sleep at night worrying that my son was going to be in the Bismarck prison. I had a vision of him in an orange jumpsuit and handcuffs," she said. "You don't put somebody in peril of going to prison on a 50.1 percent standard."
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