By James Romoser
Zach McCoy hadn't done anything wrong. But when Google sent him a cryptic, legalistic email in early 2020 notifying him that the police were demanding access to some of his data, he was alarmed.
"I thought, 'If the police department was trying to get my Google account, there's no way that anything good is going to happen to me,'" McCoy recalled. "It was all I could think about."
McCoy, now a 37-year-old resident of Tampa, Fla., had been swept up in a cutting-edge law-enforcement tool: so-called geofence warrants, which allow investigators to obtain a trove of cellphone-location data and identify anyone who was near a specific place at a specific time.
These broad, location-based warrants have emerged in the past decade as an important tool for law enforcement. Most famously, federal investigators used them to identify hundreds of people who were present during the riot at the U.S. Capitol on Jan. 6, 2021.
But "geofencing" has also created misplaced suspicions about law-abiding citizens and spurred legal challenges around the country.
Now, the Supreme Court is weighing a bank-robbery case from Virginia to decide whether geofence warrants are an unconstitutional invasion of privacy. The case, set to be argued Monday, is the latest test of how a core provision of the Bill of Rights -- the Fourth Amendment's protection against unreasonable searches and seizures by the government -- applies in the digital age.
McCoy, who works in tech support for a software company, was unaware of the legal debate around geofencing when he became a target of it.
After receiving the email from Google and scrambling to hire a lawyer, he learned that the police in Gainesville, Fla., where he was living at the time, were looking into a March 2019 burglary. Unluckily for McCoy, the home that had been burglarized was located on a street where he regularly rode his bicycle in a loop.
On the day of the burglary, McCoy had cycled past the address three times. He was using a fitness app that tracked his movements with pinpoint accuracy, and the digital trail was stored in his Google account.
So when Gainesville police served Google with a warrant seeking the location data of any user who had come near the home on the day in question, McCoy's repeated presence would have raised obvious suspicion.
His lawyer filed a lengthy motion that persuaded investigators to drop the warrant, and McCoy moved on with his life. Six years later, he says he understands why police rely on location data to generate leads but is glad the Supreme Court is reviewing the practice.
Geofence warrants instruct technology companies to turn over data about any of their users who passed through a given geographic radius during a particular window of time. The area encompassed by the geofence can be larger than several football fields. Minute-by-minute location tracking is based on GPS data, pings to nearby cellphone towers, Bluetooth beacons and Wi-Fi connections.
The data can be remarkably effective at identifying new suspects in cold cases. But it can also reveal information about the movements of innocent people, including their visits to sensitive places like churches, doctor's offices or political organizations.
Defenders of geofence warrants say the challengers overstate the privacy implications. They point out that users consent to share their location data with technology service providers, and they argue that people have no right to privacy when visiting public places.
"An individual has no reasonable expectation of privacy in movements that anyone could see, that he has opted to allow a third party to analyze for its own purposes, and that are sufficiently short-term that they reveal little, if anything, about the patterns of his life," the Trump administration's solicitor general, D. John Sauer, wrote in a legal brief.
Moreover, Sauer wrote, eliminating geofence warrants would "handicap the investigation of major crimes."
The case at the high court was brought by Okello Chatrie, who is serving a 12-year prison sentence for robbing a credit union near Richmond, Va. Chatrie says the geofence warrant that was used to identify him was unconstitutional.
Privacy advocates, civil-liberties groups and tech companies have weighed in on Chatrie's side, urging the Supreme Court to limit the use of the warrants. Alphabet unit Google, meanwhile, has taken a step to curb them.
More than 500 million Google users have the platform's location-history function enabled, and until recently, the company had stored all of that data on its own servers. But by July 2025, the company had migrated the data to users' individual devices. So Google no longer has the technical ability to search its user database and identify all users who were present at particular locations.
Google filed an amicus brief at the Supreme Court describing users' location data as a kind of "digital diary of a person's travels" that should have strong privacy protections under the Fourth Amendment.
Despite the company's new practice, geofence warrants can still be effective for police to gather location information from other tech companies that store it in the cloud. And the Supreme Court's decision, which is expected by early July, could affect similar efforts by law enforcement to obtain users' data in other ways.
McCoy, for his part, is like millions of Americans: He routinely allows apps to record his location. Even his brush with a geofence warrant six years ago didn't change that.
"I'm a technology enthusiast; I gain a lot from these types of things," McCoy said. "And because I work in technology, I understand that this was an edge case."
Write to James Romoser at james.romoser@wsj.com
(END) Dow Jones Newswires
April 26, 2026 11:00 ET (15:00 GMT)
Copyright (c) 2026 Dow Jones & Company, Inc.
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