Katz v. United States

389 U.S. 347 (1967).

One-Sentence Takeaway:  The Fourth Amendment protects people, not places, and, therefore, its prohibition against unreasonable searches and seizures applies to all places (even those accessible by the public) where the person has a “reasonable expectation of privacy.”

Katz v. United States
The case involved Defendant’s use of an enclosed public telephone booth.

Katz was convicted in a federal court for transmitting wagering information via telephone across state lines.  The evidence against Katz included telephone recordings obtained by the FBI agents by placing an electronic listening device on the outside of the enclosed telephone booth used by Katz.  During his trial, Katz moved to suppress this evidence, but the trial court overruled his objection.  The court of appeals affirmed the trial court’s ruling by reasoning that the Fourth Amendment was not implicated because there was no “physical entrance into the area occupied.”

The issue presented to the U.S. Supreme Court was whether the Fourth Amendment was violated where the law enforcement officials placed an electronic listening recording device to the top of a public telephone booth without a warrant.

In a 7-1 opinion, the Court ruled that Katz’s Fourth Amendment rights against unreasonable searches and seizures were violated and a physical trespass by the law enforcement officers was not required to implicate the protections of the Amendment.

The Court reasoned that, “Fourth Amendment protects people, not places [and what] a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection [while] what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.”  Id. at 351-352 (emphasis added).  Thus, the Court held that any form of electronic surveillance such as wiretapping that violates a person’s reasonable expectation of privacy constitutes a search under the Fourth Amendment, even if no actual physical trespass took place.

By so holding, the Court overruled its decision in Olmstead v. United States, 277 U.S. 438 (1928) that Fourth Amendment is not violated unless there is some trespass into a “constitutionally protected area.”

After Katz, the inquiry into whether a search is covered under the Fourth Amendment involves determining whether the person searched had a reasonable expectation of privacy in the area where, and at the time, he/she was searched.

Further Reading

Supreme Court Syllabus:

Petitioner was convicted under an indictment charging him with transmitting wagering information by telephone across state lines in violation of 18 U.S.C. § 1084. Evidence of petitioner’s end of the conversations, overheard by FBI agents who had attached an electronic listening and recording device to the outside of the telephone booth from which the calls were made, was introduced at the trial. The Court of Appeals affirmed the conviction, finding that there was no Fourth Amendment violation, since there was “no physical entrance into the area occupied by” petitioner.


1. The Government’s eavesdropping activities violated the privacy upon which petitioner justifiably relied while using the telephone booth, and thus constituted a “search and seizure” within the meaning of the Fourth Amendment. Pp. 389 U. S. 350-353.

(a) The Fourth Amendment governs not only the seizure of tangible items, but extends as well to the recording of oral statements. Silverman v. United States, 365 U. S. 505, 365 U. S. 511. P. 389 U. S. 353.

(b) Because the Fourth Amendment protects people, rather than places, its reach cannot turn on the presence or absence of a physical intrusion into any given enclosure. The “trespass” doctrine of Olmstead v. United States, 277 U. S. 438, and Goldman v. United States, 316 U. S. 129, is no longer controlling. Pp. 389 U. S. 351, 389 U. S. 353.

2. Although the surveillance in this case may have been so narrowly circumscribed that it could constitutionally have been authorized in advance, it was not in fact conducted pursuant to the warrant procedure which is a constitutional precondition of such electronic surveillance. Pp. 389 U. S. 354-359.

369 F.2d 130, reversed.

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