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Privacy Rights in the Digital Age

Katz v. United States, 389 U.S. 347 (1967)

by Ethan P. Fallon

A 7–1 decision, with a majority opinion by Justice Potter Stewart, in which the U.S. Supreme Court ruled that the government's activities in electronically listening to and recording Charles Katz's telephone conversations violated his right to privacy and constituted a search and seizure in violation of the Fourth Amendment. The Court's landmark decision announced that the Fourth Amendment “protects people, not places.” This rationale rejected long-standing precedent whereby the primary Fourth Amendment inquiry was whether the government had committed a physical trespass. Justice John Marshall Harlan II's concurrence would later be used as the touchstone for Fourth Amendment analysis. Following Katz, the primary Fourth Amendment inquiry became whether the government intruded upon an individual's reasonable expectation of privacy.

Charles Katz was seen making phone calls in public telephone booths during certain hours of the day and on a nearly daily basis. Federal Bureau of Investigation (FBI) special agents subsequently attached microphones on top of two public telephone booths that Katz was known to frequent. The microphones had wires attached to them that led to a voice recorder. The microphones were capable of recording one end of telephone conversations conducted within the booths.

FBI agents obtained multiple audio recordings of Katz's telephone conversations. The recorded conversations revealed that Katz was placing bets and obtaining gambling information. The FBI then directed an agent to rent a room next to Katz's apartment, where the agent proceeded to listen to conversations through the common wall without the use of any electronic devices. The agent's notes and the audio recordings were used to obtain a warrant to search Katz's apartment. The agents seized items related to materials and instrumentalities involved with placing bets and wagers. Katz was subsequently arrested and charged with an eight-count indictment for violating a federal statute that prohibited the interstate transmission by wire communication of bets or wagers, or information assisting in the placing of bets or wagers by a person engaged in the business of betting or wagering.

At trial, the government sought to introduce into evidence the audio recordings and physical evidence they obtained against Katz. Katz sought to suppress the evidence, arguing that it was obtained from an illegal search and seizure in violation of the Fourth Amendment. The trial court disagreed and convicted Katz on all counts. The Ninth Circuit affirmed the district court, noting that the FBI agents did not physically intrude into the area occupied by Katz in the telephone booth, therefore precluding any possible Fourth Amendment violation.

The U.S. Supreme Court agreed to review the issue of whether the government's electronic surveillance of Katz's telephone conversations violated the Fourth Amendment. As an initial matter, the Court rejected the parties' contention that the proper inquiry should be whether a public telephone booth was a “constitutionally protected area.” Rather, the inquiry should be focused on the individual because the Fourth Amendment protects people, not places.

Justice Stewart also noted that the Fourth Amendment cannot be interpreted as a general “right to privacy.” Instead, the Fourth Amendment protects individuals from certain types of governmental intrusions, some of which may not implicate privacy concerns at all. The protection of an individual's general right to privacy is largely left to state law.

In analyzing Katz's privacy expectations, the Court stated that an individual in a telephone booth retains the protection of the Fourth Amendment, just as he would at a friend's apartment, in a taxicab, or in a business office. By entering a telephone booth and shutting the door behind him, Katz sought to exclude the “uninvited ear” and rightly assumed that his conversations would not be broadcast publicly. The Court also explained that public telephones played a vital role in private communication.

The government argued that the surveillance technique it used to record Katz did not involve a physical penetration of the telephone booth, thereby foreclosing the possibility of a Fourth Amendment violation. The Court acknowledged that that the absence of a physical intrusion would have normally precluded a Fourth Amendment violation, citing Olmstead v. United States, 277 U.S. 438 (1928) and Goldman v. United States, 316 U.S. 129 (1942). The Court nonetheless departed from the narrow view that property interests control the right of the government to search and seize and rejected the “trespass” doctrine as articulated in prior cases.

The Court reasoned that, once the proper focus was placed on the person and not the area searched, the Fourth Amendment cannot turn on whether a physical intrusion occurred. Consequently, the government's surveillance of Katz's telephone conversations violated his privacy and constituted a search and seizure within the meaning of the Fourth Amendment.

The Court nonetheless acknowledged that the investigation of Katz was narrowly confined and noted that a neutral and detached magistrate could have constitutionally authorized, with appropriate safeguards, the surveillance of Katz. Here, however, the agents did not rely on a warrant to record Katz's conversations, and the government could not point to any exigent circumstances justifying the warrantless search. Consequently, the U.S. Supreme Court reversed the Court of Appeals.

While the Supreme Court reversed the Court of Appeals' decision 7–1, three justices wrote separate concurrences and one justice dissented. Most notably, Justice John Marshall Harlan penned a concurrence that would later become the benchmark for Fourth Amendment analysis. Justice Harlan wrote that whether a government search constitutes a search under the Fourth Amendment rests on a two-part test: (1) that the individual had a subjective expectation of privacy and (2) that the individual's expectation of privacy is one that society is prepared to recognize as reasonable. Justice Harlan's “reasonable expectation of privacy” test was explicitly adopted in Smith v. Maryland, 442 U.S. 735 (1979), and it remains as the primary inquiry for courts to consider when analyzing Fourth Amendment issues.

Further Reading

1 

Kerr, Orin S. “Four Models of Fourth Amendment Protection.” Stanford Law Review 60, no. 2 (2007): 503–551.

2 

LaFave, Wayne R. Search and Seizure: A Treatise on the Fourth Amendment, 5th ed. St. Paul: West Publishing, 2014.

3 

Stuntz, William J. “Privacy's Problem and the Law of Criminal Procedure.” Michigan Law Review 93, no. 5 (1995): 1057–1062.

4 

Winn, Peter. “Katz and the Origins of the ‘Reasonable Expectation of Privacy’ Test.” McGeorge Law Review 40 (2009): 1–9.

See also: Constitutional law; Criminal justice (criminal procedure); Electronic surveillance; Fourth Amendment to the U.S. Constitution; Olmstead v. United States; Privacy Laws, Federal; Privacy Laws, State; The Right to Privacy; Supreme Court of the United States; Wiretapping

Citation Types

MLA 9th
Fallon, Ethan P. "Katz V. United States, 389 U.S. 347 (1967)." Privacy Rights in the Digital Age, edited by Christopher T. Anglim & JD, Salem Press, 2016. Salem Online, online.salempress.com/articleDetails.do?articleName=PRDA_0127.
APA 7th
Fallon, E. P. (2016). Katz v. United States, 389 U.S. 347 (1967). In C. Anglim & JD (Ed.), Privacy Rights in the Digital Age. Salem Press. online.salempress.com.
CMOS 17th
Fallon, Ethan P. "Katz V. United States, 389 U.S. 347 (1967)." Edited by Christopher T. Anglim & JD. Privacy Rights in the Digital Age. Hackensack: Salem Press, 2016. Accessed May 30, 2026. online.salempress.com.