There are currently more cell phones in the U.S. than there are people. Given the increasingly mobile-dependent state of our society, it should come as no surprise that law enforcement in recent years has zeroed in on cell site location information (“CSLI”) as a crucial source of potential evidence in criminal investigations. In 2016, AT&T alone received 70,528 law enforcement requests for CSLI, many without a warrant. That works out to nearly 200 CSLI requests per day. In fact, these requests have become so prevalent that cell phone companies now provide self-service portals to law enforcement to help meet the constant stream of demands.

The way cell towers work is fairly straightforward: Each individual side or “site” of a cell tower contains antennas that detect the radio signals from your cell phone. Depending on where you are, your phone “pings” the nearest site, enabling you to get service. These connections occur when you make a phone call, send or receive a text message, and even when an idle background application refreshes. In rural areas, cell tower coverage might reach as far as twenty miles. In high-density urban areas, where towers are more numerous, coverage will probably only span about a mile or two at most, enabling law enforcement to piece together a much more precise picture of a person’s location over time.

Under the Stored Communications Act (“SCA”), the government may forgo a warrant and obtain a court order for CSLI if “specific and articulable facts show[] that there are reasonable grounds to believe that the contents of a wire or electronic communication, or the records or other information sought, are relevant and material to an ongoing criminal investigation.” This standard is lower than the probable cause required by a warrant, begging the question – does permitting the government to access historical CSLI without a warrant violate the Fourth Amendment’s guarantee of protection from unreasonable search and seizure? The Supreme Court is poised to answer that question in Carpenter v. United States.

In Carpenter, the defendant was charged with committing a series of armed robberies. A key piece of the government’s evidence was 127 days-worth of historic CSLI data showing that the defendant had been in the area of the robberies at the times of the crimes. These records had been obtained without a warrant in accordance with Section 2703(d) of the SCA.

Relying in large part on what is known as the “third-party doctrine,” the Sixth Circuit held that Section 2703(d) as applied to historical CLSI does not violate the Fourth Amendment. The Court reasoned that when a person uses their cell phone, they are aware that locational information is shared with the service provider, thus negating any reasonable expectation of privacy they might otherwise have in that information. This third-party disclosure authorizes the government to access these “business records” directly from the cell phone company without a warrant.

The third-party doctrine originates from Smith v. Maryland, a case holding that police do not violate a person’s Fourth Amendment rights by installing a pen register to record the numbers dialed from that person’s home phone. According to the Smith court, although the contents of one’s phone conversations are protected, information about the sender or receiver is not, since one willingly discloses that information to the phone company every time one places a call.

In his petition for certiorari, the petitioner in Carpenter argues that the third-party doctrine is ill-suited for the modern age and overshadowed by two more recent Supreme Court decisions: Riley v. California and United States v. Jones (we’ve blogged about Riley and Jones previously, including here and here). Riley recognized a privacy interest in the contents of one’s cell phone due to the “vast quantities of personal information” stored there. Jones, on the other hand, held unconstitutional the government’s placement of a GPS tracker on an individual’s car for twenty-eight days. Five sitting justices believed that the length and precision of such locational monitoring offended Fourth Amendment expectations of privacy. Both Riley and Jones seem to suggest that – address/content distinctions aside – the quantity of warrantless information obtained matters.

While the parties bicker over quantifiers like length and precision, the unspoken query of Carpenter runs much deeper: the viability of the third-party doctrine itself. Essentially, the question Carpenter poses is this – does sharing your information with one person (i.e. a cell phone company) mean you have to share it with everyone? In today’s society where owning a cell phone is a pre-requisite to participation in modern life, the Supreme Court should think long and hard before answering that question in the affirmative.