The Supreme Court today issued a 5-4 ruling stating that law enforcement must first seek a warrant before obtaining historical cell phone location data from cellular carriers, reversing a decade-long practice by law enforcement. The "Carpenter case" focused on a criminal by the name of Timothy Carpenter, who was busted for a string of armed robberies thanks to historical location data obtained by MetroPCS without a warrant, police claiming that because the MVNO already had his data, there could be "no reasonable expectation of privacy."
The Supreme Court's ruling shot down that narrative, Chief Justice John Roberts stating that the government's warrantless access to cell-site records over a period of time "contravenes that expectation" of privacy.
"The fact that such information is gathered by a third party does not make it any less deserving of Fourth Amendment protection," said Roberts.
"Because location information is continually logged for all of the 400 million devices in the United States -- not just those belonging to persons who might happen to come under investigation -- this newfound tracking capacity runs against everyone," he added.
It's worth noting that the ruling, while huge, is also a bit narrow in that it only applies to historical cell phone location data, not real-time location data tracking or so-called cell tower dumps. Groups like the ACLU remained jubilant at the ruling, which had been highly anticipated by privacy rights organizations.
"This is a groundbreaking victory for Americans’ privacy rights in the digital age,” said ACLU attorney Nathan Freed Wessler, who argued the case before the court last November. "The Supreme Court has given privacy law an update that it has badly needed for many years, finally bringing it in line with the realities of modern life. The government can no longer claim that the mere act of using technology eliminates the Fourth Amendment’s protections."