Your phone constantly tracks and records its location and transmits the information to your wireless carrier. Most phone companies keep that data — known as “cell site location information” — for up to five years. And until last week, it was pretty much available to the government for the asking.
Think for a moment what that means. If you went to a psychiatrist, a divorce lawyer, an AA meeting, a yoga class, or a 1980s dance party in the last five years, any policeman in the country could find out about it just by asking the phone company where your phone was at a given moment in time. It is as though the government placed permanent tracking devices on all of us. True, under federal law, the police had to ask for a court order under the Stored Communications Act based on a showing that the cell site data was “relevant and material to an ongoing investigation.” But that is a ridiculously low standard: pretty much anything an investigator wants to see can be tied to an investigation one way or another. Orders under 18 U.S.C. Section 2703(d) were, in practice, routinely granted by both state and federal courts.
All that changed last Friday when a fractured Supreme Court ruled in Carpenter v. U.S. that grabbing cell site data constitutes a search under the Fourth Amendment. That means that use of cell site data must be reasonable. For police investigations, a search is only reasonable if it is based on a search warrant supported by probable cause. Probable cause, the Court explained, is something more than the low standard in Sec. 2703(d): “relevant and material” just means cell site evidence “might be pertinent to an ongoing investigation,” whereas probable cause requires a “quantum of individualized suspicion” before police can start rummaging. So a Section 2703(d) subpoena is not enough to support obtaining cell site data. Mr. Carpenter’s conviction, based in part on cell site location data showing his phone was near several stores at the time they were robbed, was thrown out.
But the Court was sharply divided. The 23-page majority decision by Chief Justice John Roberts was a straightforward application of the chestnut Fourth Amendment case Katz v. United States, which held that the Constitution protects “people, not places” and that where a person has a “reasonable expectation of privacy,” police need a warrant to search (in Katz, the issue was whether police could eavesdrop on a public phone booth; it was public after all). Nearly 100 pages of dissents followed, arguing variously that Katz should be overruled (Justice Thomas), that the “third party doctrine” should apply since Mr. Carpenter “voluntarily” provided his data to his phone carrier (Justice Kennedy), that seizing the phone records by subpoena or court order is not a Fourth Amendment “search” (Justice Alito), and that the judgment should be affirmed because Mr. Carpenter failed to assert a property right in the phone company data (Justice Gorsuch). The dissents demonstrated various levels of concern for — and understanding of — how deeply the exposure of cell site data invades individual privacy.
Justice Gorsuch was the most solicitous of individual rights and skeptical of law enforcement. His dissent urged litigants to press a property theory that would better fit the plain language of the Fourth Amendment than the “reasonable expectation of privacy” approach formulated long ago in Katz. In other words, Justice Gorsuch suggests that the defendant might be able to show that the cell site date consisted of his own “papers and effects,” just as a letter placed in the mail is entitled to privacy even though it is in the hands of a third party.
The majority decision also suggests that the government may need a warrant to seize other kinds of records held by third parties. After Carpenter, the government can no longer claim that records gathered by a third party are categorically denied Fourth Amendment protection. In cases where the government seeks information that implicates privacy concerns at least as great as cell-site location information – a comprehensive and retrospective catalog of an individual’s movements – the government should need a warrant to seize that information, even if it is held by a third party. Both the majority and the dissenting justices suggested that emails, despite being held by third parties like Google and Yahoo!, are one category of information that can only be obtained with a warrant after Carpenter.
Further, Carpenter affirms that individuals have a privacy interest in the “whole of their physical movements” despite the fact that they reveal their movements to others when they move through public space. Carpenter thus calls into question other mass methods of tracking people in public, such as license plate scanning and facial recognition software.
For now, though, a majority has held that orders under the Stored Communications Act are no good. If you have a case where the government obtained cell site information to help prove you were at the scene of a crime, that information probably cannot be used against you after the decision in Carpenter — unless the government got a warrant. Move to suppress it under the Fourth Amendment, and, just in case, don’t forget to argue that its use not only invades your privacy, but also that the private records belong to you.