Supreme Court rules that warrants are required for law enforcement to get cell phone location data

View of the Supreme Court building
The Supreme Court issued a new ruling on Americans' cell phone location data. (sframephoto/iStock/Getty Images Plus/Getty Images)

In a new 5-4 ruling, the Supreme Court said police need to obtain a warrant before they can get location data from the nation’s wireless operators.

The ruling is notable as it gives a victory to the ACLU and others that are pushing for stricter privacy laws in general, in order to erect legal walls around wireless customers’ location information.

The ruling also comes just days after the nation’s wireless carriers—Verizon, Sprint, T-Mobile and AT&T—said they would generally discontinue the sale of location information to third-party data brokers. That pledge, made in response to questions on the topic issued by Sen. Ron Wyden, D-Ore., followed reports of leaks of that location data.

As outlined by Reuters, today’s Supreme Court ruling reverses a lower court ruling. It essentially requires law enforcement to get a court-approved warrant in order to obtain location information on Americans’ whereabouts via carriers’ saved location information. The court said obtaining such data without a warrant amounts to an unreasonable search and seizure under the U.S. Constitution’s Fourth Amendment.

“The case before us involves the Government’s acquisition of wireless carrier cell-site records revealing the location of Carpenter’s cell phone whenever it made or received calls,” wrote Chief Justice John Roberts in the ruling (PDF). “This sort of digital data—personal location information maintained by a third party—does not fit neatly under existing precedents. Instead, requests for cell-site records lie at the intersection of two lines of cases, both of which inform our understanding of the privacy interests at stake.”

Added Roberts: “While the records in this case reflect the state of technology at the start of the decade, the accuracy of CSLI [cell-site location information] is rapidly approaching GPS-level precision. As the number of cell sites has proliferated, the geographic area covered by each cell sector has shrunk, particularly in urban areas. In addition, with new technology measuring the time and angle of signals hitting their towers, wireless carriers already have the capability to pinpoint a phone’s location within 50 meters. … Accordingly, when the Government accessed CSLI from the wireless carriers, it invaded Carpenter’s reasonable expectation of privacy in the whole of his physical movements.”

And in Roberts’ conclusion, he wrote that “in light of the deeply revealing nature of CSLI, its depth, breadth, and comprehensive reach, and the inescapable and automatic nature of its collection, the fact that such information is gathered by a third party does not make it any less deserving of Fourth Amendment protection. The Government’s acquisition of the cell-site records here was a search under that Amendment.”