Conflicting duties may occur in the law. This case from the American Medical News is an excellent example. A grand jury issued a subpoena to the Cleveland Clinic for medical records. The patient whose records were released sued for breach of privacy. The case is not settled.
While I assume that the Cleveland Clinic is a smart place with many able attorneys, it may be the case that in this matter, they were caught between conflicting duties. Apparently they were prohibited from notifying the subject of the subpoena of the inquiry, since it came from a grand jury. But it is likely that further steps may have taken place before complying. Anyone can issue a subpoena. They do not require or generally receive any sort of judicial review and may be inappropriate or overbroad, and can be objected to if not quashed. They may however not be ignored.
A key issue with any subpoena is that the subject of the subpoena ought to be notified and given the right to object, and the recipient of a subpoena on a patient ought not automatically comply without careful review as to privacy issues. Physicians ought to consider consulting their own attorney in such matters. Many times their malpractice carrier will provide assistance at no cost in such matters.