The Private Search Doctrine After Jones

126 Yale L.J. F. 326 (2017)

12 Pages Posted: 8 Jan 2017

See all articles by Andrew MacKie-Mason

Andrew MacKie-Mason

University of Chicago, Law School, Students

Date Written: January 2, 2017


In United States v. Jacobsen, the Supreme Court created a curious aspect of Fourth Amendment law now known as the private search doctrine. Under the private search doctrine, once a private party has conducted an initial search independent of the government, the government may repeat that search, even if doing so would otherwise violate the Fourth Amendment. The private party’s search renders the subsequent government “search” not a search in the constitutional sense.

Jacobsen is based on the privacy theory of the Fourth Amendment introduced by the Court in Katz v. United States. According to the Court in Jacobsen, a private search — even if unauthorized — destroys an individual’s reasonable expectation of privacy. Thus, by merely repeating the search, the government does not further infringe on a person’s privacy. The private search doctrine is invoked by courts to justify police actions with somewhat surprising frequency.

In 2012 — twenty-eight years after Jacobsen — the Supreme Court restructured Fourth Amendment doctrine in United States v. Jones. In Jones, the Court held that the reasonable expectation of privacy test is not the only definition of a Fourth Amendment search. A search also occurs if the police trespass on a constitutionally protected area in order to obtain information, even if the trespass does not violate the property owner’s reasonable expectation of privacy. The full implications of Jones are still being explored. In this Essay, I argue that Jacobsen is irrelevant to the trespass definition of a search under Jones. A prior private search may destroy a person’s expectation of privacy, but it does not change whether the police trespassed on a constitutionally protected area in order to obtain information. Therefore, a government trespass that qualifies as a search under Jones is still a search even if its scope is limited to the scope of a prior private search. Jacobsen comes into play only if it is necessary to appeal to Katz to characterize the government action as a search.

Keywords: Fourth Amendment, Search, Private Search Doctrine, Jacobsen, Jones

Suggested Citation

MacKie-Mason, Andrew, The Private Search Doctrine After Jones (January 2, 2017). 126 Yale L.J. F. 326 (2017). Available at SSRN:

Andrew MacKie-Mason (Contact Author)

University of Chicago, Law School, Students ( email )

Chicago, IL
United States

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