The Real Problem with Katz Circularity

12 Pages Posted: 6 Apr 2021 Last revised: 9 May 2022

See all articles by Raff Donelson

Raff Donelson

Chicago-Kent College of Law - Illinois Institute of Technology

Date Written: April 3, 2021


The Fourth Amendment protects people against "unreasonable searches" by police. To operationalize this protection, courts must have a workable definition of a search. Since 1967, the Supreme Court has used the two-step Katz test as a primary measure of when a search has occurred. Under Katz, a court will find that something has been subject to search when (1) the individual in question has a subjective expectation of privacy in that thing and (2) such an expectation of privacy would be reasonable. From early on, commentators have decried the Katz test as circular and have urged courts to adopt something else. This Essay explains what the circularity worry really amounts to: the worry is about courts using improperly reduced expectations of privacy as a reason to withhold Fourth Amendment protection. This worry is much broader than most commentators have seen, and this broader framing allows one to deflect recent concerns that Katz circularity (more narrowly construed) is a myth. With the ‘circularity’ worry properly understood, the Essay offers a way to deal with it: courts could simply drop Step One of Katz.

Keywords: privacy, Katz test, Katz circularity, policing, search and seizure, Fourth Amendment

Suggested Citation

Donelson, Raff, The Real Problem with Katz Circularity (April 3, 2021). 65 St. Louis University Law Journal 809 (2021), Available at SSRN:

Raff Donelson (Contact Author)

Chicago-Kent College of Law - Illinois Institute of Technology ( email )

565 W. Adams St.
Chicago, IL 60661-3691
United States

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