Almost everyone "fails" the HGN test. The problems with the HGN test are numerous, but the main issues are 1) it's validity and accuracy depend tremendously on the officer performing it correctly (most don't), 2) the results are very subjective (see No. 1), 3) it is nearly impossible to verify independently. We could all watch a walk-and-turn or one-legged stand test on the police video and generally tell if someone passed or not, but only the performing officer can see the subject's eyes. Too often, the officer moves the focus object too quickly, doesn't keep it in place long enough at the max deviation and is either too close or too far. Also, the test is far too often performed with the subject having the police strobes in view, leading to optokinetic nystagmus, caused by the eyes trying to focus on the flashing lights. Passing traffic can cause this also.
In theory, UIPD is supposed to stick to campus property and the public roadways immediately abutting that property. Not sure what UI property is at the corner of Linn and Prentiss.