Quantifying Katz: Empirically Measuring "Reasonable Expectations of Privacy" in the Fourth Amendment Context

Both the constitutional bases of the right to privacy and the specific contours of the right have generated significant debate among scholars4 and the justices of the U.S. Supreme Court.5 Indeed, commentators assert that the term privacy in the legal context refers to three distinct rights: one grounded in the Fourth Amendment's guarantee of freedom from government intrusion into an individual's home or on to an individual's person;6 one emanating from the penumbras of several amendments to the Constitution vis-à-vis the Fourteenth Amendment's Due Process Clause,7 which concern the liberty and autonomy to make certain crucial personal decisions;8 and one stemming primarily from statutory enactments and the law of torts, which safeguard the ability of a person to restrict dissemination of personal information. 11 Whatever the sources and scope of the nebulous right to privacy may be, the Fourth Amendment to the U.S. Constitution provides a clear substantive right designed to protect people's privacy in their persons, homes, papers, and effects.12 The contemporary framework for applying the protections of the Fourth Amendment was adopted in Katz v. United States.13 Reasoning that the Fourth Amendment's Search and Seizure Clause protects people, not places,14 Justice Harlan articulated a two-part test for determining whether the Amendment's protections applied in a given case: [...] the person seeking the Fourth Amendment's protection must have exhibited an actual (subjective) expectation of privacy; and second, that subjective expectation of privacy must be one that society is prepared to recognize as reasonable. [...] we join Slobogin and Schumacher in recommending that judges engage in the process of constitutional factfindings (i.e., using empirical research) rather than basing their decision on the "suppositions of thoughtful reflection"453 when deciding cases in which objective reasonability of a reasonable expectation of privacy is at issue.