US supreme court hears whether smartphone location data warrants infringe users’ privacy

After officers interviewed witnesses at the bank Chatrie robbed and reviewed security footage, they had no leads. In a geofence warrant request, law enforcement requested that Google provide phone location data for a 30-minute period before and after the robbery from all cellphones within 150 meters of the bank, bringing in Chatrie’s phone location data but also information on 19 other accounts. The detective on the case asked Google for more data on all of these people, but the tech company pushed back, and eventually he only requested further information on nine people. Towards the end of the investigative process, that number whittled down to three devices; one was Chatrie’s, and the information included an email address with his name.

The US government has argued in legal filings that Chatrie chose to allow Google to collect and use his phone location data, and that investigators identified him through a warrant – although the plaintiff’s lawyers have argued this warrant was overly broad.

Google, for its part, has changed some of its geofencing policies since Chatrie was arrested. The tech giant has transferred this location data off its servers and onto people’s phones, so that it can’t comply with geofencing warrants in the same way anymore, said Matthew Tokson, a law professor at the University of Utah. But the government is increasingly trying to obtain this information directly from cell phone providers and other companies, he adds. The case still affects “privacy protections for data stored in cloud services and collected by consumer apps”, the Electronic Privacy Information Center noted in a press release.

Privacy advocates warn the implications of this case go far beyond suspected criminals. “If the government doesn’t need to get a warrant or link something to a crime, it could monitor a protest or an abortion clinic or a gun range or a church or an AA meeting or a doctor’s office,” Tokson says. Some justices were worried about the broader privacy implications, too.

If the court rules that a geofence warrant doesn’t constitute a search by law enforcement, “our privacy rights might be completely eviscerated”, Ohm said. “It would lead to a lot of unregulated police activity.” The fourth amendment of the US constitution protects against “unreasonable search and seizure”. Both Ohm and Tokson got the sense from the judges’ remarks on Monday that at least some justices seemed likely to find these geofence warrants counted as a search, which should bring some relief to privacy advocates.

Justice Sonia Sotomayor suggested on Monday that she wasn’t convinced by the government’s argument that short-term location information doesn’t reveal much about an individual’s patterns of life. She explained how people take their phones everywhere, from the bathroom, to a cannabis shop to a brothel. “It really doesn’t matter … whether it’s a minute that you’re searching for or six weeks, it’s not the time that’s an issue – it’s whether or not private information in which you have a reasonable expectation of privacy will be sought,” she said.