The rights of parties litigant being subordinate to the rights of the public at large, there are some matters of public interest into which courts may not pry. The disclosure of secrets of state, such as communications between public officers, transactions between heads of departments of state and their subordinates, or between a governor and his military officer, the report of a military commission of inquiry to the Secretary of War, information obtained for the purpose of the enforcement of the criminal law, would be highly prejudicial to the public welfare. And where an attorney for a party litigant pushes his examination of witnesses to a point where the divulgence of state secrets is sought, the witness may refuse to answer on the ground of privilege. The privilege not only extends to public officers, but their subordinates as well, and any person who may have knowledge of such public matters, even though not in office.