The Supreme Court last week added another layer of confusion to the vexed law of unreasonable searches and seizures regarding law-enforcement use of cell phone data to ferret out criminal activity. In Carpenter v. United States, Chief Justice John Roberts, speaking for a five-member majority (including the four liberal justices—Ginsburg, Breyer, Kagan, and Sotomayor), ruled that information collected on Timothy Carpenter’s whereabouts, pursuant to the Stored Communications Act (SCA), was inadmissible. The SCA allows law enforcement to access certain telephone company records under a court order when it “offers specific and articulable facts showing that there are reasonable grounds to believe” that the records sought “are relevant and material to an ongoing criminal investigation.” Notwithstanding the SCA, police can now access historical cell-site location information (CSLI) only if they first obtain a warrant by meeting the higher standard of probable cause under the Fourth Amendment.

Carpenter is incorrect.

The facts of the case are as follows: In 2011, the police arrested four men suspected of robbing a Radio Shack and T-Mobile store in and around Detroit. These suspects confessed that they had participated in a number of local robberies, and gave the police the cell phone numbers of some of their other confederates, including Carpenter. Pursuant to the SCA, the police then obtained two orders from Federal Magistrate Judges commanding the men’s cell phone carrier, Metro PCS, to supply CSLI data, which is generated routinely and accurately in order to maintain and operate the networks efficiently. The police obtained about 130 days of data, which placed Carpenter near the sites of each robbery at the time of occurrence. This information helped secure Carpenter’s conviction.