Justice Brennan on no-knock raids, castle doctrine, and the Fourth Amendment in Ker v. California.
The recognition of exceptions to great principles always creates, of course, the hazard that the exceptions will devour the rule. If mere police experience that some offenders have attempted to destroy contraband justifies unannounced entry in any case, and cures the total absence of evidence not only of awareness of the officers’ presence but even of such an attempt in the particular case, I perceive no logical basis for distinguishing unannounced police entries into homes to make arrests for any crime involving evidence of a kind which police experience indicates might be quickly destroyed or jettisoned. Moreover, if such experience, without more, completely excuses the failure of arresting officers before entry, at any hour of the day or night, either to announce their purpose at the threshold or to ascertain that the occupant already knows of their presence, then there is likewise no logical ground for distinguishing between the stealthy manner in which the entry in this case was effected, and the more violent manner usually associated with totalitarian police of breaking down the door or smashing the lock.
Back in 1963, Brennan was prescient on no-knock raids and police militarization. See chapter four of Rise of the Warrior Cop for more.