Difference Between Terry Stop and a Usual Traffic Stop
The Supreme Court compared the usual traffic stop to a "Terry stop," rather than to a formal arrest. Id.
A Terry stop is not an arrest requiring probable cause; rather it is an investigative seizure made with a reasonable suspicion of criminal activity. Terry v. Ohio (1968), 392 U.S. 1, 88 S. Ct. 1868, 20 L. Ed. 2d 889.
The Court found the traffic stop exception to Miranda to be constitutionally valid because a traffic stop is temporary, brief, public and substantially less police-dominated than the type of interrogation at issue in Miranda itself. Id. at 437-439.
The Court stated that although a traffic stop curtails freedom of movement by the detainee and imposes some pressure to answer questions, the pressure does not sufficiently impair the privilege against self-incrimination to warrant a Miranda warning. Id. at 436-437.
Thus, the Court determined that an officer making a traffic stop can "ask the detainee a moderate number of questions to determine his identity and to try to obtain information confirming or dispelling the officer's suspicions." Id. at 439.