Rene,
Aside from the issue (mentioned earlier) of students not being asked to provide documentation to YOU, and YOU not being held responsible for making decisions based on that documentation, I think the problem you describe runs deeper. I don't think you should be held responsible for defending the academic integrity of the nursing program. You are only in a position to explain why the student is or is not succeeding in YOUR class.
Oh... wait. I made an assumption that you are an instructor. If you are a counselor or an admissions rep then my answer would be slightly… >>>