Fair trafficking rules of medical school admission

I woke up early today and stopped by the post office on my way to work to mail my signed paperwork and deposit check reserving my spot in the University of Colorado School of Medicine class of 2013. It sounds very final, but it's not. In fact, it's quite possible that I might not know where I'll be going to medical school for several months yet. The uncertainty is bearable because I know that, regardless of what happens, I am already in.

Medical school applicants and admissions committees abide by a set of rules that are designed to facilitate the process of figuring out who goes where. Granted, I haven't yet gone through the entire process, but my perspective at this time is that these rules actually do work well.

I can accept as many offers of admission as I like, so long as by a certain date (this year, May 15), I withdraw my acceptance to all schools but one. Likewise, admissions committees are required, by a certain date (this year, March 30), to make enough offers of admission to fill their freshman class. As applicants withdraw their acceptances, admissions committees then make more offers of admission until the freshman class is filled. This means that, even if I haven't yet heard from a school by March 15, I might still be offered admission.

In fact, so long as an applicant has not matriculated (e.g. formally started a program by going to orientation or classes), an applicant is free to switch from one school to another. This has even been known to happen on the day before the first day of classes. What this means to me is that, hypothetically, I could move up to Denver expecting to start medical school up there only to find out at the last minute that UCSD is offering me admission. What would I do in that situation? We'll cross that bridge when we come to it.