By Deandra Grant, J.D., M.S. (Pharmaceutical Science), ACS-CHAL Forensic Lawyer-Scientist
Right now, your phone knows where you are. It knows where you were an hour ago, yesterday, last month, and last year. If you use Google Maps, an Android phone, or any Google app with location services enabled, Google has been recording your movements in a database called Sensorvault which is a repository that, until recently, held the continuous location history of hundreds of millions of users.
If a crime occurred anywhere near you (ex. the bank you walked past on your way to lunch, the gas station on your commute, the park where your kid’s soccer game was played) law enforcement can obtain a “geofence warrant” ordering Google to identify every device that was in the area during a specified time window. Not the suspect’s device. Every device. Yours included.
The Supreme Court will hear oral arguments in Chatrie v. United States on April 27, 2026, to decide whether this practice violates the Fourth Amendment. The case has been called “the most important Fourth Amendment issue of this generation.” It will affect every person who carries a phone which means it will affect you.
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How a Geofence Warrant Works
A traditional search warrant identifies a specific person or place to be searched and specific items to be seized, supported by probable cause to believe evidence of a crime will be found there. A geofence warrant inverts this process entirely.
Here is how it typically works, in three stages:
Stage 1: The Digital Dragnet
Law enforcement defines a geographic area (the “geofence”) and a time window. They submit this to Google, which searches its Sensorvault database and returns anonymized location data for every device that was present in the area during that window. In the Chatrie case, the geofence covered a 17.5-acre area, including not just the bank that was robbed but also a church, public roads, parking lots, and surrounding businesses, for a one-hour window.
At this stage, law enforcement does not know who any of the devices belong to. But Google has just identified every person who happened to be in that neighborhood during that hour.
Stage 2: Narrowing the List
Law enforcement reviews the anonymized data and identifies “devices of interest” based on their movements and proximity to the crime scene. Google then provides additional location data for those devices by expanding the geographic and temporal scope to show where the devices went before and after the geofenced period. This allows investigators to see if a device’s movements are consistent with what a suspect would have done.
Stage 3: Unmasking
Based on the expanded location data, law enforcement further narrows the list and asks Google to de-anonymize the remaining devices, revealing the names, email addresses, and phone numbers of the users. In the Chatrie case, this process identified Okello Chatrie, who was subsequently arrested and charged with bank robbery.
The fundamental problem, from a Fourth Amendment perspective, is that no one in stages 1 or 2 was a suspect. Every person whose data was swept up in the geofence (i.e. the churchgoers, the commuters, the people getting coffee, the person walking their dog) had their location data searched by law enforcement without any individualized suspicion that they had committed a crime. The warrant was not based on probable cause as to any particular person. It was a demand for information about everyone.
The Constitutional Question: Is This a General Warrant?
The Fourth Amendment prohibits “unreasonable searches and seizures” and requires that warrants “particularly describ[e] the place to be searched, and the persons or things to be seized.” This language was written in direct response to the “general warrants” and “writs of assistance” used by the British Crown which were sweeping orders that authorized government agents to search anyone, anywhere, for any evidence of wrongdoing.
The Framers considered general warrants to be among the most dangerous tools of government power. The Fourth Amendment’s particularity requirement exists specifically to prevent the government from casting wide nets and seeing what turns up.
A geofence warrant, critics argue, is exactly that: a digital general warrant. It does not name a suspect. It does not describe a particular device to be searched. It casts a geographic and temporal net and sweeps up the data of every person in the area (the overwhelming majority of whom are innocent) and then sorts through the results to find a suspect. The investigation does not begin with probable cause and proceed to a search. It begins with a search and proceeds to probable cause.
The Fifth Circuit (which covers Texas) has already reached this conclusion. In United States v. Smith (2024), the Fifth Circuit held that “geofence warrants are modern-day general warrants and are unconstitutional under the Fourth Amendment.” The Texas Court of Criminal Appeals reached a similar result in Wells v. State (2025). The Supreme Court will now decide the question for the entire country.
Why This Should Concern Everyone Who Carries a Phone
If you are reading this on a phone, your device is generating location data right now. And the implications of geofence warrants extend far beyond criminal investigations.
You Don’t Have to Commit a Crime to Become a Suspect
A geofence warrant does not target suspects. It targets geography. If you walked past a bank that was being robbed, drove through an intersection where a shooting occurred, or sat in a coffee shop next to a building where drugs were being sold, your phone data can be swept up in a geofence warrant. You become a “person of interest” not because of anything you did, but because of where your phone was.
In the Chatrie case, the geofence covered 17.5 acres and captured data for an entire hour. Everyone who attended the nearby church during that hour was swept up. Everyone who drove through the area was swept up. Everyone who was shopping, eating, or simply passing through was swept up. Their location histories were reviewed by law enforcement, and some were asked to provide additional data without any reason to believe they had committed a crime.
The Chilling Effect on Constitutional Rights
The Brennan Center, the Knight First Amendment Institute, and other civil liberties organizations have warned the Court that geofence warrants threaten far more than criminal defendants’ rights. They enable the government to identify:
- Everyone who attended a political protest or rally
- Everyone who visited a particular place of worship
- Everyone who entered an abortion clinic
- Everyone who visited a newsroom or met with a journalist
- Everyone who walked into a defense attorney’s office
- Everyone who attended a support group meeting, a union hall, or a political organizing event
These are not hypothetical scenarios. They are the existing capability of geofence warrants. If the Supreme Court upholds this practice, there is no constitutional barrier to law enforcement using geofence warrants to identify the participants in any constitutionally protected activity that takes place in a physical location.
The “Reverse Search” Problem
Geofence warrants are part of a broader category of “reverse searches” which are warrants that start with a search term or data point and work backward to identify users, rather than starting with a suspect and searching for evidence. Other reverse searches include “keyword warrants” (requiring Google to identify everyone who searched for a specific term) and “reverse content warrants” (requiring a platform to identify everyone who viewed a specific video or webpage). If the Court approves geofence warrants, civil liberties groups warn, it will open the door to all of these reverse-search techniques.
How We Got Here: From Carpenter to Chatrie
The legal foundation for challenging geofence warrants was laid by the Supreme Court in Carpenter v. United States (2018), where the Court held that the government’s acquisition of historical cell-site location information (CSLI) from a wireless carrier constituted a Fourth Amendment “search” requiring a warrant. Chief Justice Roberts wrote that CSLI provides “an intimate window into a person’s life, revealing not only his particular movements, but through them his familial, political, professional, religious, and sexual associations.”
Carpenter established that location data is constitutionally protected and that the mere fact of sharing data with a third party (like a phone carrier or Google) does not eliminate the user’s Fourth Amendment rights. Chatrie asks the next question: even if the government needs a warrant to get location data, can the warrant be a geofence that sweeps up everyone in an area, or must it specifically identify the person whose data is sought?
The answer will determine whether the Fourth Amendment’s particularity requirement has any meaning in the age of mass digital surveillance.
What This Means for Criminal Defense in Texas
The Fifth Circuit Is Already on Your Side
Texas federal defendants already have the benefit of the Fifth Circuit’s holding in Smith that geofence warrants are categorically unconstitutional. And the Texas Court of Criminal Appeals reached a similar conclusion in Wells. If you are facing state or federal charges in Texas and geofence warrant data was used in the investigation, your defense attorney should already be filing a motion to suppress.
However, both Smith and Wells ultimately allowed the evidence under the good-faith exception by finding that law enforcement relied on the warrant in good faith before the courts declared it unconstitutional. If the Supreme Court rules in Chatrie that geofence warrants are unconstitutional, the good-faith exception becomes much harder for prosecutors to invoke in future cases, because law enforcement can no longer claim they didn’t know the technique was unlawful.
Cell Tower Data and Location Evidence in Texas Cases
Even if your case does not involve a formal geofence warrant, the principles at stake in Chatrie apply to all location-based evidence. Cell tower data, GPS records from phones and vehicles, Wi-Fi connection logs, and app-based location tracking are all used routinely by prosecutors in Texas criminal cases from drug trafficking to murder to DWI. The defense must evaluate how the location data was obtained, whether it required a warrant under Carpenter, whether the warrant satisfied the Fourth Amendment’s particularity requirement, and whether the data is accurate enough to support the prosecution’s claims about the defendant’s location.
Doug Huff’s digital forensics training includes the evaluation of cell tower data, GPS records, and phone location evidence. Understanding the precision limitations of this data (cell tower coverage areas can span hundreds of acres in rural areas, GPS accuracy varies by environment and device, and Wi-Fi-based location estimates can be off by significant margins) is essential for challenging the prosecution’s use of location evidence in any criminal case.
Case Results
Your Phone Settings Matter
One practical takeaway from Chatrie: the data that makes geofence warrants possible exists because users opted into location tracking. Google’s Location History feature, which powered the Sensorvault database, was an opt-in setting. In December 2023, Google announced it would begin migrating Location History data from centralized cloud storage to individual devices which is a change that would make geofence warrants significantly harder to execute against newer data.
But older data may still exist in Google’s systems, and other companies (Apple, app developers, wireless carriers) continue to collect location data in various forms. Reviewing your phone’s location settings, disabling unnecessary location tracking, and understanding which apps have access to your location data are practical steps that reduce your exposure. This is not because you have anything to hide, but because you have a Fourth Amendment right not to have your movements catalogued by the government through a digital dragnet.
What Happens Next
- April 27, 2026: Oral arguments at the Supreme Court
- Late June 2026: Decision expected before the term ends
The Court could rule narrowly by deciding only whether the specific warrant in Chatrie was constitutional based on the particular facts (the size of the geofence, the length of the time window, the three-stage process). Or it could rule broadly by declaring geofence warrants categorically unconstitutional as general warrants prohibited by the Fourth Amendment, as the Fifth Circuit did in Smith. The scope of the ruling will determine whether geofence warrants remain a tool of law enforcement or join the writs of assistance in the constitutional dustbin.
Digital Evidence Defense at Deandra Grant Law
Chatrie is the latest in a series of Supreme Court cases — from Carpenter to Riley v. California (2014, requiring a warrant to search a cell phone) — that are defining the Fourth Amendment’s application to digital technology. Each of these cases reinforces the same principle: the government’s ability to collect data has outpaced the legal framework that is supposed to restrain it, and the courts are playing catch-up.
At Deandra Grant Law, digital forensics and Fourth Amendment suppression are core components of our defense practice. Doug Huff’s digital forensics training give us the ability to evaluate the prosecution’s location evidence (cell tower data, GPS records, geofence results, and device extractions) and challenge its accuracy, its methodology, and its constitutional basis. Combined with our deep experience in suppression litigation under CCP Article 38.23 (Texas’s exclusionary rule, which has no good-faith exception), our defense capability is built for the cases where digital evidence is the centerpiece of the prosecution’s theory.
If your case involves location data, phone records, or any form of digital evidence, call (214) 225-7117 or visit texasdwisite.com. Your phone may be the prosecution’s best witness. We make sure it’s not their only one.
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