On Wednesday, November 29, 2017, the Supreme Court heard arguments in the appeal of Timothy Carpenter, a man convicted and sentenced to 116 years for his role in a series of armed robberies. In proving his guilt, prosecutors relied on Carpenter’s cell phone data, which was obtained without a warrant, to link Carpenter to the scene of the robberies. The FBI obtained Carpenter’s cell phone number from one of Carpenter’s co-conspirators, who had confessed to the crimes. The FBI then obtained cell phone data from Carpenter’s cellular service provider by way of the Stored Communications Act. Using the data obtained from the service provider, the FBI was able to place Carpenter in the vicinity of the robberies. During arguments, several Justices expressed concerns about the use of this data.

The Justice Department argued that to obtain customer records, pursuant to the Stored Communications Act, law enforcement need only show that there are reasonable grounds—not probable cause—to believe that the information sought is relevant and material to an ongoing investigation. Deputy Solicitor General Michael Dreeben argued that this case is governed by the “third-party doctrine,” pursuant to which the Fourth Amendment does not protect records or information shared with a third party. At issue in Carpenter’s case, Dreeben argued, is how the government obtained Carpenter’s cell phone records. He emphasized that the records at issue were created for the cell phone provider’s own purposes and that the cell phone provider gave them to the government; it was not the government that collected the data from Carpenter. Dreeben explained that cell phone providers “function essentially as witnesses being asked to produce business records of their own transactions with customers[]” and that the government is doing nothing more than “asking a business to provide information about the business’s own transactions with a customer. And under the third-party doctrine, that does not implicate the Fourth Amendment rights of the customer.” Chief Justice John Roberts observed that such records are “not simply created by the company[.]” Rather, “It’s a joint venture with the individual carrying the phone.”

Justice Sotomayor expressed that she saw no reason why the Supreme Court should not carve out an exception to the third-party doctrine. She drew a parallel to the Supreme Court’s ruling requiring patient consent for police to obtain medical records held by hospitals. Justice Stephen Breyer agreed with Dreeben that information shared with a third party—generally—would not be shielded from disclosure, but proposed an exception to the rule in light of the significant changes in technology. Breyer later noted that the cell phone records at issue were “highly personal” and similar to medical test results.

This case is being decided in an environment of growing scrutiny of government surveillance practices and reflects concerns about the degree to which the protections of the Fourth Amendment extend to commonplace modern uses of technology. In 2012, the Supreme Court held in United States v. Jones that a warrant is required to place a GPS tracking device on a vehicle. Several years later, in 2014, it ruled in Riley v. California that a warrant is required to search a cell phone seized during an arrest.

A ruling in Carpenter v. United States is due by the end of June 2018.