(Bloomberg) — U.S. Supreme Court justices expressed concern about privacy intrusions in the digital age, hinting they may curb the power of law enforcement officials to track people using mobile-phone data.
In a spirited argument that went 20 minutes beyond its scheduled hour on Wednesday, the justices considered requiring prosecutors to get a warrant before obtaining mobile-phone tower records that show a person’s location over the course of weeks or months.
“This is highly personal information,” Justice Stephen Breyer said.
The case could have a far-reaching impact. Prosecutors seek phone-location information from telecommunications companies in tens of thousands of cases a year. More broadly, the court’s decision will help set the rules governing government access to the fast-growing trove of information available on the cloud, including data from virtual assistants, smart thermostats and fitness trackers.
Several justices, including Sonia Sotomayor and Elena Kagan, indicated they were concerned about the increasing precision of the phone location data being kept by wireless providers.
“A cell phone can be pinged in your bedroom,” Sotomayor said. “It can be pinged in a doctor’s office.”
But Justices Samuel Alito and Anthony Kennedy questioned whether location data was any more sensitive than bank records, which the court said in 1976 aren’t protected by the Constitution’s Fourth Amendment because they are in possession of the financial institution.
“Your whereabouts are publicly known,” Kennedy said. “It seems to me this is much less private” than bank records.
The session indicated the court might divide along unusual lines. Two of the court’s conservatives, Chief Justice John Roberts and Justice Neil Gorsuch, joined Breyer, Sotomayor and Kagan in suggesting they might vote to impose stronger privacy protections.
The case involves Timothy Ivory Carpenter, who is seeking to overturn his conviction for taking part in a string of armed robberies of Detroit-area Radio Shacks and, ironically, stores for wireless provider T-Mobile US Inc.
At trial, prosecutors used four months of data obtained from Carpenter’s wireless carriers to show he was within a half-mile to two miles of the location of four of the robberies when they occurred. Mobile-phone companies typically keep records that show the cell sites where their customers’ calls begin and end.
Prosecutors in most of the country can get that data without a warrant through the 1986 Stored Communications Act. That law says prosecutors need only have “reasonable grounds” to believe the information would be useful in an investigation. A court warrant would require a stronger showing of “probable cause.”
The court will rule by June in the case, Carpenter v. United States, 16-402.