Supreme Court Will Finally Decide If Cops Need Warrant To Track Phones

Police and federal agencies have argued for years they are free to gather troves of location data

Illustration: Diana Quach
Jun 05, 2017 at 6:17 PM ET

The Supreme Court will finally weigh in on one of the most contentious privacy questions of the mobile phone era: whether police need a warrant to obtain location information revealing everywhere you and your device have traveled.

The country’s highest court announced Monday that it would tackle the issue in the case of Carpenter v. United States, which involves the police’s ability to obtain historical location data revealing a suspect’s movements over time.

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For decades, police and federal agencies have asserted that they don’t need a judge’s approval to collect massive troves of geolocation data, which is stored by cellphone carriers and constantly generated as your device connects to nearby cell towers. Their justification hinged on a decades-old court decision called Smith v. Maryland, which determined that a person has no expectation of privacy in the numbers dialed on their phone, since it is “given” to a third party — in this case, the phone company.

But this so-called “third party doctrine” never anticipated the rise of cellphones, let alone ubiquitous, pocket-size computing devices that record everything we do and follow us everywhere we go. The result is that police have used the loophole to successfully obtain location information en-masse from telecommunications providers — either through so-called “tower dumps,” which compel a carrier to hand over information on every phone that connected to certain cell towers at specific times, or using cellphone surveillance devices colloquially known as stingrays. Currently, federal laws don’t regulate police use of stingrays, and some departments use them often without a warrant.

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But privacy advocates have argued it goes far beyond the scope of the original ruling, which was made in 1979, before cellphones even existed. In another privacy case that determined police must obtain a warrant before attaching a GPS tracker to a suspect’s vehicle, Supreme Court Justice Sonya Sotomayor wrote that the third party doctrine is “ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks.”