How Geofence Warrants Work—and Why Courts Disagree
Geofence warrants let police demand location data on every phone near a crime scene, turning traditional policing on its head. With the US Supreme Court set to rule on their constitutionality, here is how they work and why they spark fierce debate.
A Warrant That Works in Reverse
Traditional search warrants start with a suspect and seek evidence. Geofence warrants flip that logic. Police draw a virtual boundary—a geofence—around a crime scene on a map, specify a time window, and compel a technology company to hand over data on every device detected inside that zone. The goal is not to surveil a known person but to discover unknown ones.
First used around 2016, these "reverse location warrants" surged in popularity. Google, the primary recipient, reported receiving 982 geofence warrants in 2018. By 2020 that number had climbed to more than 11,500, according to the company's transparency reports.
How the Three-Step Process Works
Most geofence warrants follow a structured sequence designed to narrow the pool of people identified:
- Anonymized sweep. The tech company searches its location database—Google historically used a repository called Sensorvault, which held data from hundreds of millions of accounts—and returns a de-identified list of every device inside the geofence during the specified window.
- Location expansion. Investigators review the anonymized data and ask the company for additional location points before and after the target window for a subset of devices, helping them see who was merely passing through versus lingering.
- Unmasking. For the remaining devices of interest, the company reveals account-holder identities, giving police names and contact details to pursue.
The entire process can capture data from dozens—or even thousands—of phones, the vast majority belonging to people with no connection to any crime.
Why Privacy Advocates Sound the Alarm
The Fourth Amendment requires warrants to be supported by probable cause and to describe with particularity the persons or things to be seized. Critics, including the ACLU and the Electronic Frontier Foundation, argue geofence warrants fail both tests. They target a geographic area, not a specific suspect, sweeping up innocent bystanders, churchgoers, and passersby.
The concern extends beyond location. Legal scholars warn that upholding geofence warrants could open the door to other "reverse searches"—such as keyword warrants demanding data on everyone who Googled a particular term or visited a specific website—chilling free speech and association.
Courts Are Deeply Split
American courts have reached starkly different conclusions. In 2024, the Fifth Circuit (covering Texas, Louisiana, and Mississippi) ruled in United States v. Smith that geofence warrants are "modern-day general warrants" and inherently unconstitutional. Yet in 2025, the Texas Court of Criminal Appeals reached the opposite conclusion in Wells v. State, finding them permissible—creating the unusual situation where geofence warrants are presumptively unconstitutional in Texas federal courts but valid in Texas state courts.
In April 2026, the Minnesota Supreme Court overturned a murder conviction because the geofence warrant used was overly broad, though it stopped short of banning the technique altogether.
The Supreme Court Steps In
The landmark case Chatrie v. United States brings the question to the US Supreme Court for the first time. Okello Chatrie was identified as a bank robbery suspect after police obtained a geofence warrant covering a 150-meter radius—an area encompassing homes, businesses, and a church in Richmond, Virginia. The justices will decide whether this type of search violates the Fourth Amendment.
The case echoes the Court's 2018 ruling in Carpenter v. United States, which held that accessing seven days of historical cell-site location data requires a warrant. Geofence warrants raise the stakes further: they don't just track a suspect's movements—they identify unknown individuals from a crowd.
Google Changed the Game
In a move that may ultimately reshape the debate, Google announced it would shift location-history storage from its central servers to users' individual devices. As of mid-2025, Google can no longer respond to geofence warrants because it simply does not hold the centralized data. However, other companies still collect location information, and law enforcement may seek new data sources—meaning the constitutional question remains vital regardless of any single company's policy.
What Comes Next
However the Supreme Court rules, geofence warrants have exposed a fundamental tension in digital-age policing: the power of location data to solve crimes versus the right of millions of people not to become suspects simply because their phone was nearby. The outcome will shape the boundaries of surveillance technology for years to come.
