The Fourth Amendment Future of Public Surveillance: Remote Recording and Other Searches in Public Space

Public video survdllance is changing the way police fight crime and terrorism. This was especially clear in the aftermath of the Boston Marathon bombing when law enforcement found images of the two suspects by analyzing surveillance images gathered by numerous public and private cameras. Such after-the-fact video surveillance was equally crucial to identifying the culprits behind the 2005 London subway bombing. But the rise of camera surveillance, as well as the emergence of drone-based video monitoring and GPS-tracking methods, not only provides an important boon for law enforcement, but also raises a challenge for constitutional law: As police gain the ability to technologically monitor individuals' public movements and activities, does the Fourth Amendment's protection against "unreasonable searches"place any hurdles in thdr way ?In the 2012 case, United States v. Jones, five justices, in two separate concurrences, signaled that it does-at least when the monitoring becomes too intense or prolonged. Their suggestion, however, raises two significant problems. First, it provides no principled basis for marking the point at which public survdllance morphs from a means by which police monitor public space into a Fourth Amendment "search. " Under the "mosaic theory " embraced by the D.C. Circuit, such surveillance becomes a search only when it captures enough data points from an individual's public life to construct a detailed picture (or "mosaic") of her movements and associations. But how detailed may such a picture be before it is too detailed ? Do police engage in a search simply by watching someone continuously, even if they do so without drones, GPS units, or other advanced technology ? Second, the concurring opinions do not explain why the Fourth Amendment, if it does cover public surveillance of this kind, does not also cover the information-collecting police do when they simply watch a pedestrian or a driver. As Justice Scalia wrote in Jones, "Th[e] Court has to date not deviated from the understanding that mere visual observation does not constitute a search. " But if police collect the same information from watching a driver as they do from tracking him with GPS technology, why would thdr watching not also be a search ?This Article proposes a solution to each of these challenges by offering a two- part definition of a Fourth Amendment "search" in a public space. Police engage in a search when they (1) not only observe, but also record, images or sounds of people or events outside police presence; or (2) magnify details on a person or documents or other items the person is carrying and thereby reveal information that would not otherwise be apparent without a pat-down or a stop-and-search of a person's papers or effects.This technology-based or design-based definition of what constitutes a "search" avoids the problems that arise when the Fourth Amendment analysis regarding what constitutes a "search" is based on an investigation's duration or intensity. Under the technology-based or designed-based definition, police engage in a search as soon as they begin recording remote events or magnifying otherwise invisible details, whether they have done so for two minutes or two weeks. Additionally, under this approach, Fourth Amendment constraints only apply to survdllance that goes beyond unadorned visual surveillance. This test is more workable and more in accord with Fourth Amendment logic. Recording is a search because, more than any other element of public surveillance, it allows police to engage in dragnet-style investigation of all activities in a public space. By transforming ephemeral occurrences into permanent records, recording allows government officials to search public lives frame by frame, much like they might search documents file by file. Certain types of magnification could also constitute a search because, just as a telescope focused on a home may be functionally equivalent to a home entry and search, certain types of magnification may be functionally equivalent to a physical search of persons, papers, or effects. …