Fourth Amendment search jurisprudence is nominally based on a "reasonable expectation of privacy," but actual doctrine is detached from society's conception of privacy. Courts rely on various binary distinctions: Is a piece of information secret or not? Was the observed conduct inside or outside? While often convenient, none of these binary distinctions can adequately capture the complicated range of ideas encompassed by "privacy." Over the last decade, privacy theorists have begun to

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... that a consideration of context is essential to a full understanding of privacy. Helen Nissenbaum's theory of contextual integrity, which characterizes a right to privacy as the preservation of expected information flows within a given social context, is one such theory. Grounded, as it is, in context-based normative expectations, the theory describes privacy violations as unexpected information flows within a context, and does a good job of explaining how people actually experience privacy. This Article reexamines the meaning of the Fourth Amendment's "reasonable expectation of privacy" using the theory of contextual integrity. Consider United States v. Miller, in which the police gained access to banking records without a warrant. The theory of contextual integrity shows that Miller was wrongly decided because diverting information meant purely for banking purposes to the police altered an information flow in a normatively inferior way. Courts also often demonstrate contextual thinking below the surface, but get confused because the binaries prevalent in the doctrine hide important distinctions. For example, application of the binary third party doctrine in cases subsequent to Miller obscures important differences between banking and