|Our Government is the potent, the omnipresent teacher. For good or for ill, it teaches the whole people by its example. Crime is contagious. If the Government becomes a law-breaker, it breeds contempt for law; it invites every man to become a law unto himself; it invites anarchy. To declare that in the administration of the criminal law the end justifies the means — to declare that the Government may commit crimes in order to secure the conviction of a private criminal — would bring terrible retribution. Against that pernicious doctrine this Court should resolutely set its face.
– Louis Brandeis (1856-1941)