Also known as: Katz test · Katz v. United States · Katz privacy test · reasonable expectation of privacy test
Written by attorneys · grounded in primary & secondary sources — see below
A Fourth Amendment doctrine that protects individuals rather than places by determining whether government action violates a person's reasonable expectation of privacy. The doctrine inquires first whether the individual exhibited an actual subjective expectation of privacy and second whether that expectation is one society is prepared to recognize as reasonable.
Kylie Kerr entered a public phone booth, closed the door behind her, and spoke in a lowered voice while discussing personal financial matters. Officers attached a listening device to the exterior of the booth and recorded her conversation without a warrant. The recording captured statements that formed the basis for later charges against her. Because Kerr took steps to shield her words from public hearing, the surveillance intruded on a protected privacy interest.
Isaiah and fellow managers met in an unlocked conference room during lunch breaks to discuss manufacturing changes. They closed the door and lowered their voices but left the door ajar on other occasions and allowed coworkers to enter for documents. Agents attached a listening device to the exterior wall and recorded the discussions without a warrant. The recordings were admissible because the open workplace practices prevented any reasonable expectation that the conversations would remain private.
Select any source to read its text and confirm it supports the definition.
The doctrine requires first that the person exhibit an actual subjective expectation of privacy and second that the expectation be one society recognizes as reasonable. Both prongs must be satisfied for Fourth Amendment protection to attach.
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When a person invites others into the space or leaves doors open, any subjective expectation of privacy is undermined and society will not regard the expectation as reasonable. The doctrine therefore supplies no Fourth Amendment protection for conversations knowingly exposed in that manner.
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Yes. The guest's repeated instructions and use of the deadbolt demonstrate a subjective expectation of privacy, and society recognizes privacy in a rented hotel room as reasonable for the duration of the stay. Covert electronic surveillance therefore constitutes a search under the doctrine.
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Protection is denied when physical features such as glass walls or thin partitions allow visual or auditory exposure to others who hold legitimate access. Society will not recognize an expectation of complete privacy as reasonable under those circumstances.
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