Orin Kerr: trespass was never the exclusive Fourth Amendment test (2012) research Note

By Kristopher A. Nelson
in June 2018

300 words / 2 min.
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Orin Kerr explains how the modern assumption that traditional Fourth Amendment doctrine revolved around the law of trespass is wrong.


Orin Kerr, in “The Curious History of Fourth Amendment Searches,” reinvestigates the history of how courts interpreted “searches” under the Fourth Amendment—and realizes that the “widely shared assumption” of modern jurists that the “pre-Katz search doctrine was in fact based on trespass law” is, in actual fact, wrong.1

Neither the original understanding nor Supreme Court doctrine equated searches with trespass. … In short, the common wisdom is false. Before Katz, the Court did not use a specific formulation to identify what counted as a Fourth Amendment search. Supreme Court cases on the meaning of “searches” generally reasoned by analogy to the canonical example of home invasion. The Court began to focus on physical intrusion as a guide starting in the 1920s.2

It was really Olmstead v. United States, decided in 1928, that “physical penetration of a protected area”—still not quite trespass—became a key guide to decided when a search had occurred.3 And it was in Katz, which has become known for the idea that “privacy protects people, not places,” that the “Court further cemented the property-to-privacy myth.”4


  1. Orin S. Kerr, “The Curious History of Fourth Amendment Searches,” The Supreme Court Review 2012, no. 1 (2012): 68. See also United States v. Jones, 132 S. Ct. 945, 950 (2012) (“for most of our history the Fourth Amendment was understood to embody a particular concern for government trespass upon the areas (‘persons, houses, papers, and effects’) it enumerates”); Katz v. United States, 389 U.S. 347 (1967).
  2. Kerr, “Curious History,” 2-3 (emphasis added).
  3. Kerr, “Curious History,” 3; Olmstead v. United States, 277 U.S. 438 (1928).
  4. Kerr, “Curious History,” 3; Katz, 389 U.S. at 352-53.

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