Reasonable Expectations of Anonymity

73 Pages Posted: 19 Jul 2016 Last revised: 20 Jul 2016

See all articles by Jeffrey M. Skopek

Jeffrey M. Skopek

University of Cambridge; Harvard Law School

Date Written: April 14, 2015


The Supreme Court has concluded that the Fourth Amendment's protections do not apply to information that has been exposed to the public. This conclusion is deeply flawed and derives from the mistaken conflation of anonymity and privacy. Although anonymity and privacy are similar in that both maintain the secrecy of personal information, they differ in a fundamental and legally relevant way: privacy hides the information, whereas anonymity hides what makes it personal. Understanding this difference reveals compelling substantive and formal reasons for interpreting the Fourth Amendment to protect not only reasonable expectations of privacy, but also "reasonable expectations of anonymity." Further, the incorporation of this new analytic concept into Fourth Amendment jurisprudence yields significant value: first, by identifying otherwise-unrecognizable ways in which new techniques of big data implicate the Constitution, and second, by delivering on the unfulfilled promise of the Supreme Court's teaching that the Fourth Amendment "protects people, not places."

Keywords: privacy, anonymity, surveillance, identification, familial searching, big data, Fourth Amendment, Katz

Suggested Citation

Skopek, Jeffrey M., Reasonable Expectations of Anonymity (April 14, 2015). Virginia Law Review, Vol. 101, pp. 691-762, 2015, University of Cambridge Faculty of Law Research Paper No. 6/2015, Available at SSRN:

Jeffrey M. Skopek (Contact Author)

University of Cambridge ( email )

Faculty of Law
10 West Rd
Cambridge, CB3 9DZ
United Kingdom

Harvard Law School ( email )

1563 Massachusetts Avenue
Cambridge, MA 02138
United States

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