In remarks at Rice University in 2012, Chief Justice John G. Roberts Jr. predicted that the challenge for the Supreme Court for the next 50 years would be how to adapt old, established rules to new technology. On Friday, Roberts and four of his colleagues admirably rose to that challenge by holding that the 4th Amendment requires law enforcement to obtain a warrant to obtain a suspect’s cellphone location records.
The ruling was a victory for Timothy Carpenter, who was convicted in federal court in a series of armed robberies partly on the basis of location data from his cellphone providers. The FBI had obtained the records not with a warrant based on probable cause but with a court order based on the lesser standard that there were “reasonable grounds” to believe that the records were “relevant and material to an ongoing investigation.”
Writing for himself and Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan, Roberts held that a warrant was required because Carpenter had a “reasonable expectation of privacy” in his cellphone records. That was because such records, by tracking a subscriber’s whereabouts, provide “an intimate window into a person’s life, revealing not only his particular movements, but through them his familial, political, professional, religious, and sexual associations.”
The court made a similar observation about the contents of cellphones when it ruled in 2014 that police needed a warrant to search the phones of persons under arrest, a ruling in which Roberts also wrote the majority opinion.
The difference is that cellphone location records are considered the property of the service providers, not the subscribers. In previous rulings, the Supreme Court has said that individuals had no reasonable expectation of privacy in information they turn over to “third parties” such as banks and telephone companies. For example, in 1979 the court upheld the warrantless installation of a device called a pen register to record which phone numbers a suspect called.
But, without overruling those decisions, Roberts wrote on Friday that few people in 1979 “could have imagined a society in which a phone goes wherever its owner goes, conveying to the wireless carrier not just dialed digits, but a detailed and comprehensive record of the person’s movements.” Therefore, he reasoned, given “the unique nature of cellphone location records,” a warrant would be required to obtain them, except in emergency situations such as an active shooting, a bombing or the abduction of a child.
Although Roberts described Friday’s decision as “narrow,” it’s a significant step forward in adapting the 4th Amendment to the digital age. While some states, such as California, already require police to obtain warrants for cellphone information, this ruling will require police in the remaining states as well as federal law enforcement officers to meet the higher standard.
Furthermore, while this decision involved location data, its reasoning could easily be extended to cover government efforts to obtain other sorts of revealing electronic information, including emails and text messages.