law unto oneself

[law unto oneself] {n. phr.}, {literary} A person who does onlywhat he wishes; a person who ignores or breaks the law when he doesn'tlike it.

Everybody in Germany feared Hitler because he was a lawunto himself.

Mr. Brown told Johnny that he must stop trying to bea law unto himself.

Compare: TAKE THE LAW INTO ONE'S OWN HANDS.