For years, police have increasingly relied on a powerful shortcut: instead of starting with a suspect, they start with a place and time, then ask a tech company for a list of phones that were there. On Monday, the Supreme Court put a constitutional label on that practice. By a 6-3 vote, the Court held that a geofence warrant is a “search” under the Fourth Amendment.
That may sound like a technical distinction, but it is not. Once the Court calls something a “search,” Fourth Amendment rules apply. In practice, Monday’s ruling means police cannot treat geofence requests as an easy workaround. The Court did not ban geofence warrants outright, but it did place them within the Constitution’s search framework and said police will now need to show probable cause.
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What is a geofence warrant?
A geofence warrant is a court order that compels a company (often a mapping or advertising platform) to identify devices that appeared within a defined geographic boundary during a defined time window. Unlike a traditional warrant, it often begins with unknown people and works backward toward possible suspects. That is why these are sometimes called reverse location searches.
To visualize it, imagine drawing a digital circle around a block, a store, or a house. The request is not “give me John’s location.” It is “give me everyone’s device that showed up in this circle during this timeframe,” and then “tell me who they are.”
The case
The decision came in Chatrie v. United States, a case arising from a 2019 robbery of a credit union outside Richmond, Virginia. Investigators used Google location data in a staged process that began broadly and became more identifying over time.
The three steps
- Step one: Google produced anonymized location data for devices found within a 150-meter radius of the credit union from 30 minutes before to 30 minutes after the robbery.
- Step two: Police narrowed the list and sought additional location data for selected devices, both inside and outside the geofence, expanding the window to two hours on each side of the robbery.
- Step three: Police narrowed again, and Google produced identifying information such as names and phone numbers for the remaining devices.
Okello Chatrie was among three individuals who were ultimately identified through the process. The location history reportedly showed him entering the geofenced area ten minutes before the robbery and leaving toward a residential area afterward. Police later found a gun, about $100,000 in cash, and a demand note.
What the Court held
The Fourth Amendment protects “the right of the people to be secure in their persons, houses, papers, and effects” against unreasonable searches and seizures. The core question in Chatrie was whether the government’s acquisition of this kind of location data counts as a “search” in the first place.
The Supreme Court answered yes: police performed a Fourth Amendment search when they obtained Chatrie’s location data from Google “because an individual has a reasonable expectation of privacy in his cell-phone location information.”
The Court did not declare every geofence warrant unconstitutional. But by treating geofencing as a Fourth Amendment search, the decision makes probable cause a required part of the government’s justification for using this tool.
Carpenter and Location History
The decision follows the Court’s 2018 ruling in Carpenter v. United States, which required a warrant to access cellphone location data. Chatrie addresses a related concern: detailed location records can reveal an intimate picture of a person’s life, even when those records sit on a company’s servers.
Justice Elena Kagan emphasized a difference between cell site location information (CSLI) and Google’s Location History. She wrote: “Most cell-phone users have no awareness of CSLI records, and would never try to retrieve them; by contrast, Google users regularly employ Location History as a personal journal. In that way, Location History resembles other private materials—e.g., emails, documents, photographs, or calendars—that even if stored on Google’s servers, a user reasonably views as his own and expects to be shielded from the ‘inquisitive eyes’ of the government.”
What changes for police
Many police agencies have used geofence requests to generate leads when they do not yet have a suspect. After Chatrie, courts will treat those requests as Fourth Amendment searches, and law enforcement will need to meet the Constitution’s standards for searching.
Three takeaways
- Probable cause is required: Police will need to show probable cause to use a geofence warrant, not simply argue that a broad location sweep might be useful.
- Scope still matters: The decision does not settle every question about how particular or narrow a geofence must be. Expect fights over radius, time window, and how many bystanders are swept in.
- Expect more challenges: When evidence comes from a geofence, defense attorneys now have a clearer Fourth Amendment basis to contest how that evidence was obtained.
What it means for your phone
Most of us carry a device that quietly records where we go, when we go there, and how long we stay. You do not have to be doing anything wrong for that data to be revealing. It can expose visits to a doctor’s office, a place of worship, a support group, a political meeting, or a friend’s home.
Monday’s ruling does not eliminate all location tracking, and it does not guarantee police will never obtain location information. But it rejects the idea that your movements through public space are automatically fair game simply because a company has records.
Are geofences banned?
No. The Court held that the practice is a “search,” which triggers Fourth Amendment protections, but it did not declare every geofence request invalid on its face.
That leaves major questions for lower courts, including:
- How narrow a geofence must be to satisfy constitutional requirements.
- How courts should weigh the privacy interests of innocent bystanders whose devices are collected in the early stages of a request.
- How much location surveillance, and over what timeframe, becomes too revealing to justify through broad requests.
Reactions and dissent
Privacy and civil liberties advocates praised the Court for recognizing the sensitivity of movement data. Andrew Crocker, Surveillance Litigation Director at the Electronic Frontier Foundation, said: “The Court reaffirmed that you have an expectation of privacy in location data that reveals your movements in the physical world, and that even short-term surveillance of these movements is a search subject to the Fourth Amendment.”
Crocker also warned about scale, noting that geofence warrants have been used “tens of thousands of times” to sweep up information about people who are not suspects, and he argued that lower courts should ultimately move to eliminate the practice entirely.
The American Civil Liberties Union also welcomed the decision. Brett Max Kaufman, senior counsel with the ACLU’s Center for Democracy, called the ruling “critical protection against invasive and overbroad government searches of our personal information.” He warned that even if one company reduces what it can provide, similar reverse searches for sensitive data held by other companies remain a continuing threat.
Three justices dissented: Samuel Alito, Clarence Thomas, and Amy Coney Barrett. Justice Alito wrote that “the Court sheds Carpenter’s self-imposed boundaries and further de-stabilizes longstanding Fourth Amendment jurisprudence.” He also argued the decision would not change Chatrie’s outcome: “Although today’s decision will send seismic waves through our Fourth Amendment doctrine, not one iota of the majority opinion will affect the outcome of this case.”
A twist for tech
Constitutional rules matter, but so do design decisions. In 2023, Google changed how some location data is stored, meaning that for many users, more information stays on the device rather than being retained in a way the company can readily produce. As a result, Google has less information to hand over if police present a geofence warrant.
Even so, the broader legal debate continues. Courts, lawmakers, and the public are still working out what “reasonable” privacy means when our phones are so good at remembering where we have been.
The bottom line
The Supreme Court’s ruling in Chatrie v. United States puts a constitutional stake in the ground: geofence warrants are Fourth Amendment searches. Police can still seek location data, but they must do so within the Fourth Amendment’s protections, including showing probable cause, and lower courts will continue to define how those protections apply to real-world geofence requests.
If you want a simple way to remember the significance, it is this: the Fourth Amendment does not only protect the inside of your home. In the smartphone era, it also reaches the story your location data can tell.