This was something that surprised me a bit when I was teaching. Colleges typically only expel students when they meet one of two criteria: The student poses an immediate danger to the people or facilities, or the student has demonstrated that are not legitimately pursuing an academic degree (i.e., they are trying to cheat their way through). Even in situations where those criteria are met, the system is generally designed to work with the students as much as possible to keep them on campus and allow them to finish their educations. Colleges and universities are classic liberal institutions, and try to be inclusive of everyone. Over the course of my classroom time, I taught a number of felons who had committed fairly terrible crimes. I once learned, halfway through a semester, that one of my students was a serial pedophile who had only recently been paroled, for example. I was a victim of another serial pedophile when I was a kid, and had a huge problem with having this guy in my classroom. In spite of my history, my dean informed me that he wouldn't be removed, and that any attempt to marginalize him or out him to the class would result in MY termination (as an adjunct, I could be fired for nearly anything). In academia, the prevailing mindset is that education should be available to everyone, no matter what you have done with your life.

In most of these sexual violence cases, the student accused of the crime simply withdraws. Once the accused is no longer a student on campus, the colleges and universities don't pursue expulsion because the former student no longer meets either of the criteria.

Part of the reason for the hesitation is idealistic. Because the student is no longer on their campus, there is no longer a danger to their students or staff. The immediate problem has been resolved, and they don't want to close the door on that person getting an education later. Part of it is also practical...in many of the cases where universities have expelled students, the accused students later sued the schools. Legally, it's like an ex employer badmouthing you to a potential new employer. If there is no legal evidence to back up their claim, then it's a libel. If you're going to publicly label someone a rapist, then you MUST be able to prove that they are a rapist in a court of law. Colleges and universities have learned that lesson the hard way, paying out large sums of money to these accused former students in settlements. Unless they have large legal coffers to defend against these suits, most universities prefer to simply allow the student to withdraw, or to indefinitely suspend them, and reserve expulsion proceedings for the cases where there is either incontrovertible evidence of the assault, or a criminal case that they can point to in support of their claim.