While the machinery of law enforcement and indeed the nature of crime itself have changed dramatically since the Fourth Amendment became part of the Nation's fundamental law in 1791, what the Framers understood then remains true today - that the task of combating crime and convicting the guilty will in every era seem of such critical and pressing concern that we may be lured by the temptations of expediency into forsaking our commitment to protecting individual liberty and privacy.
William J. BrennanThe concept of military necessity is seductively broad, and has a dangerous plasticity. Because they invariably have the visage of overriding importance, there is always a temptation to invoke security "necessities" to justify an encroachment upon civil liberties. For that reason, the military-security argument must be approached with a healthy skepticism.
William J. BrennanUse of a mentally ill person's involuntary confession is antithetical to the notion of fundamental fairness embodied in the due process clause.
William J. Brennan