Decentralizing Fourth Amendment Search Doctrine

51 Pages Posted: 21 Nov 2017 Last revised: 17 Feb 2019

See all articles by Michael Mannheimer

Michael Mannheimer

Northern Kentucky University - Salmon P. Chase College of Law

Date Written: January 8, 2018


In examining the threshold question for Fourth Amendment analysis – what constitutes a search? – both courts and commentators have generally premised their analysis on a sharp dichotomy between an approach based on trespass to real or personal property, on the one hand, and one grounded in non-property-based expectations of privacy, on the other. The trespass-based regime seemed to have given way in 1967 to the “reasonable expectation of privacy” standard. But the resurgence of a trespass-based approach in recent Supreme Court cases has served to highlight the supposed distinction between the two methodologies.

When subjected to close scrutiny, the dichotomy between the two approaches becomes highly questionable. Whether analyzed in terms of trespass or reasonable expectations of privacy, the question in close cases concerning whether government conduct constitutes a Fourth Amendment search comes down to the same essential touchstone: social norms governing privacy and seclusion. Those social norms inform both when a particular expectation of privacy should be deemed reasonable and when an incursion on property should be deemed a trespass. This social-norm-based analysis of whether a Fourth Amendment search has occurred should not be surprising. The common law governing rights to security in one’s person and property stems from longstanding custom, which is inextricably linked with social norms: the practices of a people become their social norms, which harden into custom, and custom in turn evolves into enforceable rights and interests that sometimes, though not always, find expression in positive law. Thus, expectations of privacy and trespass constitute, not two distinct tests, but rather two points on the same evolutionary scale. Our notions of trespass have as their touchstone the very same social norms that form the backbone of the reasonable expectation of privacy test.

One can articulate a uniform meaning of “search,” irrespective of whether we are operating under a “trespass” or a “reasonable expectation of privacy” model. A Fourth Amendment search occurs when, for the purpose of gathering information, government agents act contrary to law, broadly conceived – that is, law in whatever stage of evolutionary development – providing us with security vis-à-vis private actors in our persons, houses, papers, and effects. A violation of positive law that fits this definition is sufficient but not necessary to constitute a Fourth Amendment search; a violation of social norms that fits this definition, even where the norms have not yet gelled into positive law, should also be considered a search. But because law, in all its manifestations, often differs by jurisdiction, the question whether a Fourth Amendment search has occurred might be answered differently in different parts of the country, and perhaps even in different parts of the same State.

Suggested Citation

Mannheimer, Michael, Decentralizing Fourth Amendment Search Doctrine (January 8, 2018). 107 Ky. L.J. 169 (2019 Forthcoming). Available at SSRN: or

Michael Mannheimer (Contact Author)

Northern Kentucky University - Salmon P. Chase College of Law ( email )

Nunn Hall
Highland Heights, KY 41099
United States

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