Divided Supreme Court Requires Warrants for Cell Phone Location Data

On June 22, 2018, the United States Supreme Court decided Carpenter v. United States, in which it held that the government must generally obtain a search warrant supported by probable cause before acquiring more than seven days of historical cell-site location information (“CSLI”) from a service provider.

Noting “the deeply revealing nature of CSLI, its depth, breadth, and comprehensive reach, and the inescapable and automatic nature of its collection,” the Court held that an individual “maintains a legitimate expectation of privacy in the record of his physical movements captured through CSLI” that warrants Fourth Amendment protection. While the Court sought to construe its decision narrowly, the reasoning of the majority and Justice Gorsuch in his dissent raise significant questions about whether and to what extent individuals may have a reasonable expectation of privacy or possessory interest in other sensitive personal data held by third parties beyond the CSLI at issue in Carpenter.