Also known as: Katz v. United States · reasonable expectation of privacy test
Written by attorneys · grounded in primary & secondary sources — see below
A two-part inquiry used to determine whether government action constitutes a search under the Fourth Amendment. The first prong asks whether the individual exhibited an actual subjective expectation of privacy. The second prong asks whether that expectation is one that society is prepared to recognize as reasonable.
Kevin Kane entered a public telephone booth, closed the door, and spoke in a low voice while discussing private business. Federal agents attached a listening device to the exterior of the booth and recorded the conversation without a warrant. The recording captured details that formed the basis for charges against Kane.
Kurtis Kaiser and colleagues met regularly in an unlocked conference room at their manufacturing plant to discuss trade secrets. Agents attached a listening device to the exterior wall and recorded the conversations without a warrant. The recordings led to charges against Kaiser after other employees had entered the room on multiple occasions.
Select any source to read its text and confirm it supports the definition.
Keisha Kincaid used a leased warehouse office on several occasions for private meetings and left personal notes inside. Agents searched the office under a warrant issued for the larger factory and seized documents belonging to Kincaid. Kincaid moved to suppress the evidence on the ground that the search violated her own privacy interest.
Kieran Kelly stored a container in a third-party warehouse. Agents installed a beeper inside the container before it was placed there and monitored its movements without a warrant. The monitoring revealed the container's location inside a private residence and led to charges against Kelly.
Karina Kovacs rented a hotel suite and instructed staff not to enter while using the deadbolt. Officers arranged for the manager to install a concealed microphone in a vent and recorded conversations without a warrant. The recordings supplied the sole evidence for trafficking charges against Kovacs.
Kira Kapoor placed calls from her home telephone to suspected accomplices. Police obtained the numbers dialed from the telephone company without a warrant and used the list to link Kapoor to the scheme. The records formed key evidence at trial after Kapoor moved to suppress them.
The first prong requires the individual to exhibit an actual subjective expectation of privacy. The second prong requires that the expectation be one society is prepared to recognize as reasonable.
Supporting sources
No. When the room lacks locks, signs restricting access, or consistent efforts to exclude others, society does not recognize an expectation of privacy as reasonable even if participants close the door and lower their voices.
Supporting sources
No. A person without a lease, keys, or formal right to exclude others from a space lacks a legitimate expectation of privacy that society recognizes as reasonable, even after repeated invited use.
Supporting sources
Yes. Repeatedly inviting outsiders into a room, leaving the door ajar, and failing to install locks or post signs show that the individual did not consistently treat the space as private, so any expectation fails the objective prong.
Supporting sources
Yes. A guest who instructs staff not to enter and uses the deadbolt exhibits a subjective expectation that society recognizes as reasonable in the interior of a rented room.
Supporting sources
…Stanley v. Georgia , 394 U.S. 557, 564 (1969); in the Fourth and Fifth Amendments, Terry v. Ohio , 392 U.S. 1, 8-9 (1968), Katz v. United States , 389 U.S. 347, 350 (1967), Boyd v. United States , 116 U.S. 616 (1886), see Olmstead v. United States , 277 U.S. 438, 478 (1928) (Brandeis, J., dissenting); in the penumbras of the Bill…