Larry Rosenthal, Binary Searches and the Central Idea of the Fourth Amendment
Comment by: Marc Blitz
Workshop draft abstract:
Many scholars and judicial decisions have identified privacy as the central value at the root of the Fourth Amendment’s prohibition on unreasonable search and seizure. Yet, the conception of Fourth Amendment privacy is deeply contested. Fourth Amendment jurisprudence has oscillated between competing conceptions of privacy. The libertarian conception argues that the Fourth Amendment works to identify a private domain free from unwarranted governmental intrusion, while the pragmatic conception sees privacy as a function of an effort to balance liberty against law enforcement interests.
Few cases force such a clear choice between these competing conceptions as Florida v. Jardines, in which the United States Supreme Court will decide whether the use of a drug-detection dog to determine whether a home contains contraband is considered a “search,” regulated for reasonableness under the Fourth Amendment. The use of a properly trained drug-detection dog is often characterized as a “binary search” because it discloses nothing other than the presence of absence of contraband. Deciding whether a binary search should be regarded as infringing a legitimate expectation of privacy is no small matter. Indeed, to decide Jardines, one is forced to choose between the libertarian and pragmatic conceptions of Fourth Amendment privacy. From a libertarian perspective, there is no stronger candidate for a private domain free from official scrutiny than the home. Yet, there are powerful pragmatic arguments against limiting the use of binary search techniques. A binary search discloses nothing of interest about the innocent; it reveals only that an individual has utilized the privacy of the home to break the law. The decision whether to treat a binary search as infringing an expectation of privacy that we should regard as legitimate accordingly reveals a great deal about our conceptions of privacy as a legal concept. This paper will explore what the binary search in general, and the Jardines decision in particular, tell us about the character of Fourth Amendment privacy.