In 2010, the FBI sought to arrest the \u201cHigh Country Bandits,\u201d two men engaged in a rural bank robbing spree. Law enforcement could not see the Bandits\u2019 faces in surveillance videos, but a witness saw one of them use a cell phone during a robbery. To identify the suspects, the FBI sought four \u201ccell tower dumps\u201d from cell carriers, collections of the phone numbers \u201cfrom all the devices that connected to a cell site during [the] particular interval\u201d in which four of the robberies occurred. In the case of the High Country Bandits, the cell tower dumps returned the cell-site location information (CSLI) of 150,000 cell phone numbers, only two of which\u2014the Bandits\u2019 numbers\u2014appeared near all four robberies.<\/p>\n
This type of warrantless governmental collection of cell tower dump location information is becoming ubiquitous, in part because the Supreme Court in Carpenter v. United States<\/em> declined to address whether it triggers Fourth Amendment protection. The Carpenter<\/em> Court found that governmental acquisition of \u201cseven days of [historical cell-site location information] constitutes a Fourth Amendment search.\u201d But tower dumps are distinct from the Carpenter<\/em> long-term historical CSLI in two main ways. First, cell tower dumps collect cell-site location information not from one person, but from hundreds or thousands of people. Second, because tower dump CSLI typically spans only several hours or even minutes, the amount of CSLI police acquire for any given individual captured in the tower dump is likely less than the 127 days of CSLI from one individual that law enforcement obtained in Carpenter<\/em>.<\/p>\n Nonetheless, tower dumps still implicate massive amounts of user data and trigger privacy concerns \u00a0<\/sup>that potentially implicate the Fourth Amendment. Of the lower courts that have considered whether individuals have a reasonable expectation of privacy in cell tower dump CSLI, many have found that they do not. But most of those cases pre\u00addateCarpenter <\/em>and do not account for its reasoning, and most post-Carpenter <\/em>lower courts have not yet reached the merits of the issue.<\/p>\n As a result, this contribution seeks to guide future courts deciding whether to permit warrantless governmental acquisition of cell tower dump CSLI. Part I argues that cell tower dumps should constitute searches under the reasoning of Carpenter<\/em>and Justice Alito\u2019s concurrence in Jones<\/em> because governmental acquisition from cell carriers of tower dump CSLI violates an individual\u2019s reasonable expectation of privacy. Part II then proposes ways in which courts can minimize privacy intrusions into innocent individuals\u2019 tower dump CSLI under either the Fourth Amendment \u00a0<\/sup>or the Stored Communications Act.<\/p>\n