You can't be too sure

In the 21st century American colleges have begun using criminal background checks as another way to evaluate applicants. In fact, 66% of colleges and universities conduct background checks as part of the admissions process. I guess I can understand why, in our age of over-sensitivity to crime, colleges want their campuses to be safe. However, the people doing the checking often have no idea as to how such a background check should be done or interpreted.In fact, 40%  of the schools doing checks do not train their staffs on how to conduct the checks. So, are some applicants unfairly rejected?