Katz v. United States

Katz v. United States
Supreme Court of the United States
Argued October 17, 1967 Decided December 18, 1967
Full case name	Charles Katz v. United States, Leach-Lewis v. Bd. of Supervisors
Citations	389 U.S. 347 (more) 88 S. Ct. 507; 19 L. Ed. 2d 576; 1967 U.S. LEXIS 2
Case history
Prior	369 F.2d 130 (9th Cir. 1966); cert. granted, 386 U.S. 954 (1967).
Holding
The Fourth Amendment's protection from unreasonable search and seizure extends to any area where a person has a "reasonable expectation of privacy."
Court membership
Chief Justice Earl Warren Associate Justices Hugo Black · William O. Douglas John M. Harlan II · William J. Brennan Jr. Potter Stewart · Byron White Abe Fortas · Thurgood Marshall
Case opinions
Majority	Stewart, joined by Warren, Douglas, Harlan, Brennan, White, Fortas
Concurrence	Douglas, joined by Brennan
Concurrence	Harlan
Concurrence	White
Dissent	Black
Marshall took no part in the consideration or decision of the case.
Laws applied
U.S. Const. amend. IV
This case overturned a previous ruling or rulings
Olmstead v. United States (1928)

Katz v. United States, 389 U.S. 347 (1967), was a landmark decision of the U.S. Supreme Court in which the Court redefined what constitutes a "search" or "seizure" with regard to the Fourth Amendment to the U.S. Constitution.^[1][2] The ruling expanded the Fourth Amendment's protections from an individual's "persons, houses, papers, and effects," as specified in the Constitution's text, to include any areas where a person has a "reasonable expectation of privacy."^[3] The reasonable expectation of privacy standard, now known as the Katz test, was formulated in a concurring opinion by Justice John Marshall Harlan II.^[4]

The Katz test has since been used in numerous cases, particularly because of technological advances that create new questions about privacy norms and government surveillance of personal data.^[5]