A search is not justified by what it reveals. Any search requires the existence of probable cause and may require a warrant. Delay, vehicle searches, and safety issues trigger additional requirements. Prior consent validates a search. Silence is not consent. An “open field” search of unoccupied or undeveloped areas not part of a dwelling or its immediate surroundings is valid, as is surveillance from the air. A “plain touch” frisk allows seizure of weapons or contraband if it is “immediately apparent” that such exists. Issuance and execution of warrants is almost always governed by detailed regulations. The “exclusionary rule” forbids use of what is revealed by improper searches, but there are exceptions.