The Myth of Fourth Amendment Circularity

67 Pages Posted: 24 Feb 2017

Date Written: February 22, 2017


The Supreme Court’s decision in Katz v. United States made peoples’ reasonable expectations of privacy the touchstone for determining whether state surveillance amounts to a search under the Fourth Amendment. Ever since Katz, Supreme Court justices and numerous scholars have referenced the inherent circularity of the expectations of privacy framework: People’s expectations of privacy depend on Fourth Amendment law, so it is circular to have the scope of the Fourth Amendment depend on those same expectations. Nearly every scholar who has written about the issue has assumed that the circularity of expectations is a major impediment to having the scope of the Fourth Amendment depend in any way on what ordinarily people actually expect. But no scholar has tested the circularity narrative’s essential premise, which is that when salient, well-publicized changes in Fourth Amendment law occur, popular sentiment falls into line.

Our paper conducts precisely such a test. We conducted surveys on census-weighted samples of US citizens immediately before, immediately after, and long after the Supreme Court’s landmark decision in Riley v. California. The decision in Riley was unanimous and surprising. It substantially altered Fourth Amendment law concerning the privacy of peoples’ cell phone content, and it was a major news story that generated relatively high levels of public awareness in the days after it was decided. We find that immediately after the Riley decision the public began to expect greater privacy in the contents of their cell phones, though the effect was small and appears to have been confined to the 40% of our sample that reported having heard of the Riley decision. One year after Riley, these heightened expectations had disappeared completely. There was no difference from baseline two years after Riley either, with privacy expectations remaining where they were prior to the decision. Our findings suggest that privacy expectations are far more stable than judges and commentators have been assuming. Even in the ideal circumstance of a clear, unanimous, and widely reported decision, circularity in Fourth Amendment attitudes is both weak and short-lived. In the longer term, Fourth Amendment circularity appears to be a myth. The paper concludes by comparing the public’s response to Riley with its reaction to the Supreme Court’s contemporaneous Hobby Lobby decision and situates our results within the political science literature on attitudinal responses to significant Supreme Court decisions.

Keywords: Fourth Amendment, Search and Seizure, Constitutional Law, Privacy, Surveillance, Norms, Expectations, Public Opinion, Judicial Behavior, Katz, Riley, Hobby Lobby

Suggested Citation

Kugler, Matthew B. and Strahilevitz, Lior, The Myth of Fourth Amendment Circularity (February 22, 2017). 84 University of Chicago Law Review (Forthcoming), University of Chicago Coase-Sandor Institute for Law & Economics Research Paper No. 797, U of Chicago, Public Law Working Paper No. 617, Available at SSRN:

Matthew B. Kugler

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States

Lior Strahilevitz (Contact Author)

University of Chicago Law School ( email )

1111 E. 60th St.
Chicago, IL 60637
United States
773-834-8665 (Phone)
773-702-0730 (Fax)

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