In 1967, the Supreme Court decided the landmark case of United States v. Katz, which engineered a paradigm shift in Fourth Amendment law: instead of focusing solely on property interests in determining whether or not a "search" had occurred, the Court broadened the scope of the Amendment's protection to include any activity in which an individual has a "reasonable expectation of privacy." However, subsequent decisions by lower courts-as well as recent decisions by the Supreme Court itself-have shown a continuing tension in the Katz legacy.
This Article argues that an accurate application of the Katz test considers only the result of the search-the type of information that was acquired-and disregards altogether the method of the searchthe action or conduct of the agent conducting the search. Although this is a broader view of the test than some courts have adopted, this view is supported by a close textual reading of Justice Harlan's concurring opinion in Katz (which set out the "reasonable expectations" test) and is also consistent with much of the reasoning in case law from the hundred years prior to Katz. Furthermore, application of a purely "results-based" test is all the more necessary given the advances in technology that have occurred since that landmark case was decided over thirty years ago. This is especially true in the fields of computer crime, sense-enhancing technology, and binary or content-discriminating searches.
Part I of this Article analyzes the "reasonable expectation of privacy" test set out in the Katz case by briefly tracing the history behind the test and then examining how the Court has applied the test since Katz. Part II presents a "results-based" interpretation of the Katz test and places it in the context of the evolving case law on the subject. Part III examines three specific methods of investigation: computer-assisted investigations (whether of cybercrime or more traditional crimes), sense-enhancing technology, and binary or content-discriminating searches, and demonstrate the ways in which improper applications of the Katz standard have resulted in holdings that are inconsistent with Katz's original purpose-and incompatible with technology in today's world.
From Katz to Kyllo: A Blueprint for Adapting the Fourth Amendment to Twenty-First Century Technologies,
53 Hastings L.J. 1303
Available at: https://repository.uclawsf.edu/hastings_law_journal/vol53/iss6/2