Criminal Procedure, Pages 32–38

Katz v. United States

Supreme Court of the United States, 1967


Defendant illegally gambled over the phone from a public phone booth. The FBI placed a listening device on the exterior of the booth and recorded his conversation to use as evidence.

Procedural History:

  • Defendant was convicted.

  • Court of appeals affirmed because there was no physical entrance into the phone booth.


Did the FBI's listening in constitute a search?


Electronic surveillance constitutes a search under the Fourth Amendment when conducted on a person where he has a reasonable expectation of privacy, even if there was no physical trespass.


The issue is not whether or not the phone booth was a "constitutionally protected area," but whether the defendant had a reasonable expectation of privacy of his speech therein, as the Constitution protects people, not areas. Here, defendant did have such an expectation of privacy of his speech inside a phone booth. Our understanding of the Constitution has changed since Olmstead, where a trespass was held to be required, and an intrusion of privacy such as this should not be allowed.


The FBI's electronic listening constituted a search. Reversed.

Concurring Opinions:

  • Douglas: These electronic surveillance restrictions should even apply in matters of national security. Spies are people too.

  • Harlan: Like the majority said, for the Fourth Amendment to protect someone, they must expect privacy and that expectation must be reasonable. Paying to use a closed phone booth satisfies this. However, exceptions may come up in other similar cases.

  • White: A reasonableness test is appropriate here since it did not have to interfere with legitimate needs of law enforcement. If it was a matter of national security, the executive branch could reasonably wiretap people without a warrant.

Dissenting Opinion:

Black: The Constitution does not say wiretapping constitutes a search, and it should not be rewritten to include such a thing just because technology has developed and people want the Constitution to say that. Its language only considers searching and seizing tangible things, not overhearing conversations. Overhearing electronic conversations was certainly not envisioned as they were not invented yet when the Constitution was written. Yet, eavesdropping did exist, and the Fourth Amendment was not made to prevent that. Whether it is electronic or not, if the Framers wanted to prevent eavesdropping, they would have included it in the Bill of Rights.