Mapp v. Ohio,
The ignoble shortcut to conviction left open to the State tends to destroy the entire system of constitutional restraints on which the liberties of the people rest. [n11] Having once recognized that the right to privacy embodied in the Fourth Amendment is enforceable against the States, and that the right to be secure against rude invasions of privacy by state officers is, therefore, constitutional in origin, we can no longer permit that right to remain an empty promise. Because it is enforceable in the same manner and to like effect as other basic rights secured by the Due Process Clause, we can no longer permit it to be revocable at the whim of any police officer who, in the name of law enforcement itself, chooses to suspend its enjoyment. Our decision, founded on reason and truth, gives to the individual no more than that which the Constitution guarantees him, to the police officer no less than that to which honest law enforcement is entitled, and, to the courts, that judicial integrity so necessary in the true administration of justice
Mapp v. Ohio
Michigan Department of State Police v. Sitz
Petitioners concede, correctly in our view, that a Fourth Amendment "seizure" occurs when a vehicle is stopped at a checkpoint. Tr. of Oral Arg. 11; see Martinez-Fuerte, supra, at 556 ("It is agreed that checkpoint stops are ‘seizures' within the meaning of the Fourth Amendment"); Brower v. County of Inyo, 489 U.S. 593, 597 (1989) (Fourth Amendment seizure occurs "when there is a governmental termination of freedom of movement through means intentionally applied" (emphasis in original)). The question thus becomes whether such seizures are "reasonable" under the Fourth Amendment.
It is important to recognize what our inquiry is not about. No allegations are before us of unreasonable treatment of any person after an actual detention at a particular checkpoint. See Martinez-Fuerte, 428 U.S. at 559 ("claim that a particular exercise of discretion in locating or operating a checkpoint is unreasonable is subject to post-stop judicial review"). As pursued in the lower courts, the instant action challenges only the use of sobriety checkpoints generally. We address only the initial stop of each motorist passing through a checkpoint and the associated preliminary questioning and observation [p451] by checkpoint officers. Detention of particular motorists for more extensive field sobriety testing may require satisfaction of an individualized suspicion standard. Id. at 567.
Michigan Dep't of State Police v. Sitz
