Data Aggregation and the Fourth Amendment

Abstract

Data aggregation has played a role in several recent cases implicating one’s reasonable expectation of privacy under the Fourth Amendment. First, in United States v. Jones, five Supreme Court Justices relied on aggregation to depart from the public expo-sure doctrine and hold that long-term, warrantless GPS tracking violated the Fourth Amendment. Second, in Riley v. California, a unanimous Supreme Court relied on aggregation to depart from the search incident to arrest exception to the warrant requirement and hold that a warrantless search of an arrestee’s cell phone or smart phone violated the Fourth Amendment. Finally, in Commonwealth v. Augustine, the Supreme Judicial Court of Massachusetts relied on aggregation to depart from the third-party doctrine and hold that obtaining cell site location information (CSLI) without a war-rant violated the Fourth Amendment. Although these cases involved different doctrines, each court relied on data aggregation to depart from existing Fourth Amendment doctrine. This article considers where the aggregation principle may go next.