POLICY ON DOCTOR'S NOTES
In order to be excused from an exam or assignment for a medical reason, you must provide a doctor's note. This note must clearly state that the doctor is certain that you were medically unable to function on the date(s) in question. The majority of notes that I've received over the years have not met this requirement and as a result, many such notes were not accepted. Here are a few common examples of unacceptable notes:
A more helpful note (but much less common) is one where the doctor says that the student is sick on Thursday and that the student is clearly so sick that s/he must have been sick on Wednesday too. But usually the doctor is unable to honestly write this.
So the best principle is - always see the doctor on the day that you are claiming to be too sick to work. I know this is difficult, for obvious reasons. But unfortunately, it is necessary.
If a note is questionable (eg if it is one of the types listed above), then I usually call the doctor to get more information. When obtaining your note, it will speed things up if you give the doctor permission to discuss your case with me. (Of course, this isn't mandatory.)