Which case allowed police to search automobiles upon probable cause but without a search warrant?

• A. Mapp v. Ohio
• B. Carroll v. United States
• C. Katz v. United States
• D. Terry v. Ohio

Answer: (B)

The rule being tested is the automobile exception to the Fourth Amendment: police can search a car without a warrant if they have probable cause to believe it contains evidence or contraband, because a vehicle can quickly move out of reach and the evidence might be destroyed or lost. This concept was established in Carroll v. United States, which held that the mobility of vehicles creates a practical need for a warrantless search when there is probable cause to believe the vehicle contains illicit items. The search can cover parts of the car where such evidence could be hidden, given the probable cause, without requiring a warrant beforehand.

Mapp v. Ohio deals with the exclusionary rule and state court applicability, not the automobile search exception. Katz v. United States focuses on privacy expectations in electronic surveillance, not vehicle searches. Terry v. Ohio concerns stop-and-frisk based on reasonable suspicion, not warrantless automobile searches based on probable cause.