Law enforcement officials frequently draw virtual fences around areas of interest and require Google to identify every cellphone in the area using cell location history. Dubbed a “geofence search,” officers obtain a warrant that permits a multistep, give-and-take information sharing process between officers and tech employees that winnows down and identifies subjects.

On June 29, 2026, the Supreme Court ruled that whenever police obtain an individual’s cell location data, even from a third-party tech company, it constitutes a search under the Fourth Amendment of the U.S. Constitution. The Fourth Amendment protects people from unreasonable government searches and seizures, and it does so in part by requiring search warrants based on probable cause that describe the particular person or thing to be searched. A geofence warrant that identifies every phone in an area does not align well with those requirements.

In its 6-3 decision in Chatrie v. United States, the court sent the case back to the 4th U.S. Circuit Court of Appeals to determine whether the geofence warrant at issue, including each part of its three-step search process, met the Fourth Amendment’s warrant requirements.

As a privacy, electronic surveillance and tech law attorney, author and legal educator, I have spent years researching, writing, educating and advising about these kinds of privacy and legal issues, and my books on electronic surveillance and evidence are routinely cited and relied upon by courts grappling with these issues.

Google tracks the vast majority of cellphones, collecting your location, usage and device data through installed software and apps. The tracking occurs by various autonomous processes you cannot see or stop, even when you turn off location history, and Google and other companies keep that data for years. Outside of your control, your cellphone continuously creates a durable and revealing digital trail that law enforcement can obtain with a warrant.

The Chatrie case involves the hunt for a suspect in an armed bank robbery in busy Midlothian, Virginia, in May 2019, and how police settled on a man named Okello Chatrie as the perpetrator.

Detective Joshua Hylton was granted a geofence warrant that compelled Google to search its database and identify every cellphone in a 17½-acre area around the bank, including private residences........

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