Turncoat
Part of speech: noun
Definition: a traitor; one who turns against a previous affiliation or allegiance; a defector, renegade or apostate
Renegade
Part of speech: noun
Definition: An outlaw or rebel.A disloyal person who betrays or deserts his cause, religion, political party, friend, etc.
Example sentence: Chairman Chaffetz was an enthusiastic supporter of the 'USA Freedom Act,' designed to rein in the allegedly renegade NSA and its wanton depredations of American privacy.