Short term disability question

So my friend had surgery and was only planning on being out of work for 2 or 3 weeks. As of today the Dr. said that she needed to take another 4 weeks off before she returned to work. What information does her insurance company have the right to get if the Dr. says she cannot go back to work. They are giving her the run around and her work is almost demanding her to return to work on monday. Does anyone know what the insurance company has the right to ask her in terms of information and any laws that will help her in this situation? If you find some info can you let me know where i can locate it for my friend.