You may remember the term carte blanche from reading The Three Muskateers. Cardinal Richeleau issued a carte blanche to Milady de Winter. It read only, "By my word and for the good of the state, the bearer has done what has been done." This gave her unlimited power to do anything, break any law, without any consequences to herself. She was, effectively, above the law.
Of course, such a thing can, and did, backfire. When the carte blanche fell into the hands of D'Artagnion, he used it to justify Milady's execution.