As close observers of the implications of privacy law on companies’ data collection, usage and disclosure practices, we at Socially Aware were among the many tech-law enthusiasts anticipating the U.S. Supreme Court’s recent decision in Carpenter v. United States, in which the Court held that the government must obtain a warrant to acquire customer location information maintained by cellular service providers, at least where that information covers a period of a week or more.
Authored by Chief Justice John Roberts, the 5-4 opinion immediately enshrines greater protections for certain forms of location data assembled by third parties. It also represents the Court’s growing discomfort with the so-called “third-party doctrine”—a line of cases holding that a person does not have a reasonable expectation of privacy in records that he or she voluntarily discloses to a third party. In the longer run, there will likely be further litigation over whether the same logic should extend Fourth Amendment protections to other types of sensitive information in the hands of third parties as courts grapple with applying these principles in the digital age.
Anytime a cell phone uses its network, it must connect to the network through a “cell site.” Whenever cell sites make a connection, they create and record Cell Site Location Information (CSLI). Cell phones may create hundreds of data points in a normal day, and providers collect and store CSLI to spot weak coverage areas and perform other business functions.