Carpenter v. United States

Facts

In 2011, police officers arrested four men suspected of robbing Radio Shack and T-Mobile stores in Detroit. One confessed that the group had robbed nine stores across Michigan and Ohio over the prior four months. He identified 15 accomplices and gave the FBI some of their cell phone numbers. Federal prosecutors applied for court orders under Section 2703(d) of the Stored Communications Act to obtain cell phone records for Timothy Carpenter and other suspects. The statute permitted disclosure when the Government offered specific and articulable facts showing reasonable grounds to believe that requested records were relevant and material to an ongoing criminal investigation. Federal Magistrate Judges issued two orders directing Carpenter's wireless carriers, MetroPCS and Sprint, to disclose cell-site location information for incoming and outgoing calls during the robbery period. MetroPCS produced records covering 127 days. The second order requested seven days of records from Sprint, which produced two days covering the period when Carpenter's phone was roaming in northeastern Ohio. In total, the Government acquired 12,898 location points cataloging Carpenter's movements, averaging 101 data points per day. At trial, an FBI agent used this data to produce maps placing Carpenter's phone near four of the charged robberies.

Issues

1. Does the Government conduct a search under the Fourth Amendment when it accesses historical cell-site location records from a wireless carrier that chronicle a cell phone user's past physical movements?
2. Does the Fourth Amendment generally require the Government to obtain a warrant supported by probable cause before compelling a wireless carrier to disclose historical cell-site location records?

Holding

The Government invaded Carpenter's reasonable expectation of privacy in the whole of his physical movements when it acquired historical cell-site location information from his wireless carriers without a warrant supported by probable cause. Because obtaining at least seven days of historical cell-site records is a search under the Fourth Amendment, orders issued under Section 2703(d) of the Stored Communications Act based on a showing of reasonable grounds were constitutionally inadequate to authorize the acquisition.