Unpacking the Dirtbox: Confronting Cell Phone Location Tracking with the Fourth Amendment

INTRODUCTIONAnaheim, a small city in Southern California, is home to 350,000 residents, Disneyland, and an arsenal of military-grade spy equipment.1 One of the devices used by the Anaheim Police Department is the Dirtbox, a planemounted surveillance system that impersonates a cell phone tower and tricks targeted mobile phones into revealing their location within a ten-foot accuracy.2Cell phone location tracking raises substantial privacy concerns and thus implicates the Fourth Amendment.3 The Fourth Amendment guards against government encroachment on individuals' privacy, but its protections are not triggered unless a "search" has occurred.4 The U.S. Supreme Court has determined that a search occurs when the government violates an individual's reasonable expectation of privacy.5 Thus, if an individual has a reasonable expectation of privacy in his or her cell phone location information, the government must obtain a warrant before performing Dirtbox surveillance.6 Courts and scholars are divided, however, as to whether people have a reasonable expectation of privacy in cellular location data and as to what constitutional limitations, if any, should be placed on Dirtbox surveillance.7This Note argues that Dirtbox surveillance amounts to a Fourth Amendment search and therefore the government must be required to get a warrant before using this technology.8 When the government uses a device to determine an individual's location with sufficient accuracy to pinpoint them within a constitutionally protected space, such as the home, the Fourth Amendment demands that this search be conducted pursuant to a warrant.9 Part I explores the foundations of the Fourth Amendment and discusses its application to location tracking. 10 Part II examines new developments in location tracking, including the Dirtbox.11 Part II also outlines the efforts by the Department of Justice and various legislatures to regulate the use of the Dirtbox and other cell-site simulators.12 Part III argues that the government's use of the Dirtbox and other cell-site simulators amounts to a Fourth Amendment search and that the U.S. Supreme Court and Congress must provide individuals with greater protection against novel surveillance techniques.131THE EVOLUTION OF THE FOURTH AMENDMENTThe Fourth Amendment protects against unreasonable searches by requiring the government to obtain warrants for almost all searches.14 To trigger this protection, however, a court must determine that a search has taken place.15 Section A of this Part explores the evolution of the Fourth Amendment.16 Section B examines the Fourth Amendment in the context of location monitoring.17A. The Fourth Amendment Search, from Places to PeopleThe definition of search, under the Fourth Amendment, has evolved substantially over the past fifty years.18 At the time of the Fourth Amendment's ratification, a search was best understood as a physical trespass by the government on one's private property.19 In the latter half of the twenti- eth century, the U.S. Supreme Court expanded the scope of the term, considering a search to occur when the government violates an individual's reasonable expectation of privacy.20 Although this new model generally expanded privacy protection, the subsequent third-party doctrine carved out swaths of information from the scope of the Fourth Amendment.21In 1886, in Boyd v. United States, the U.S. Supreme Court provided the first interpretation of the term "search."22 In Boyd, the Court examined preRevolutionary cases to determine that the compelled production of private papers constituted a search under the Fourth Amendment, analogizing forced document production to the physical invasion of one's home.23 In doing so, the Court expressed a clear preference for a liberal interpretation of the Fourth Amendment.24In 1928, in Olmstead v. United States, the Court retreated from its liberal interpretation of the Fourth Amendment in Boyd to the physical trespass model of colonial times. …