Constitutional Limits on Geofence Warrants: Particularized Probable Cause for Non-Anonymous Location Data

Introduction

United States v. Okello Chatrie, No. 22-4489 (4th Cir. en banc Apr. 30, 2025), marks the first en banc decision of the Fourth Circuit to confront the constitutionality of “geofence” warrants under the Fourth Amendment. Okello Chatrie was identified as the principal suspect in an armed bank robbery only after law enforcement obtained his Google Location History through a multi-step geofence warrant. After he was charged in the Eastern District of Virginia, Chatrie moved to suppress all evidence obtained from that warrant, arguing it violated the Fourth Amendment’s warrant clause, probable-cause requirement, and particularity requirement.

On rehearing en banc, a divided Court affirmed the district court’s denial of suppression—but did so solely on the ground that the detective relied in good faith on a magistrate’s warrant. The majority declined to resolve whether non-anonymous Location History data is subject to Fourth Amendment protection or whether a geofence warrant, as executed here, can ever satisfy particularity or probable cause. This commentary examines the background of geofence warrants, summarizes the Fourth Circuit’s rulings, and analyzes the competing views of Fourth Amendment scope and the role of the good-faith exception in digital search cases.

Summary of the Judgment

Facts: After a bank robbery in Richmond, VA, Detective Hylton obtained a geofence warrant requiring Google to produce Location History data for all devices within a 150-meter radius of the bank. Following Google’s three-step anonymization and narrowing protocol, law enforcement identified nineteen devices at Step 1, narrowed to nine at Step 2 (expanding the time window and losing geographic limits), and then obtained identifying account information for three devices at Step 3. One of those devices belonged to Okello Chatrie.
Procedural History: Chatrie was indicted on armed-robbery charges and moved to suppress his location data. The district court concluded that the geofence warrant likely violated the Fourth Amendment but applied the good-faith exception to deny suppression. He pleaded guilty conditionally and appealed.
En Banc Decision: A 14-1 panel issued a per curiam opinion affirming on good faith grounds. Thirteen judges joined the per curiam opinion; one judge dissented from the refusal to address the underlying Fourth Amendment question. Several judges wrote separate concurrences or dissents disagreeing on the scope of Fourth Amendment protection for geofence warrants.

Analysis

1. Precedents Cited

Katz v. United States (1967) and Justice Harlan’s two-part “reasonable expectation” test: did the individual expect privacy, and does society recognize it as reasonable?
Smith v. Maryland (1979) and United States v. Miller (1976): the third-party doctrine, which holds that data voluntarily exposed to third parties ordinarily carries no Fourth Amendment protection.
United States v. Knotts (1983) and United States v. Karo (1984): limits on tracking devices in public, and the extension of warrant requirements when surveillance enters private domains.
United States v. Jones (2012): GPS tracking for 28 days on a private vehicle violated trespass and, in five Justices’ view, reasonable expectations of privacy for long-term monitoring.
Kyllo v. United States (2001): use of thermal imaging to scan private interior details of a home is a search.
Carpenter v. United States (2018): historical cell-site location information (CSLI) for several days is a search because CSLI is “qualitatively different” and “deeply revealing.”
Leaders of a Beautiful Struggle v. Baltimore Police Dep’t (2021 en banc): long-term aerial surveillance violates reasonable expectations of privacy.

2. Legal Reasoning

The en banc majority declined to decide whether non-anonymous Location History data is protected by the Fourth Amendment, citing uncertainty about the technology, Google's changing policies, and the absence of controlling authority. Instead, the Court affirmed the district court’s denial of suppression solely on the good-faith exception under United States v. Leon. Because Detective Hylton reasonably relied on a magistrate’s warrant in novel circumstances, the majority held that exclusion would not deter future wrongdoing.

Separate opinions paint a sharply divided landscape:

Affirmance on Good Faith Only: Chief Judge Diaz and several others urged restraint, deferring “grand constitutional pronouncements” and resting on the Leon exception.
Rejecting “No Search” Theories: Judges Wilkinson and Niemeyer reasoned that Location History is like bank records or pen-register data—voluntarily shared and thus not a search under Miller/Smith.
Recognizing a Search for Non-Anonymous Data: Judges Wynn, Berner, Richardson, Heytens, and one dissenting judge held that Location History data likely traceable to an individual is deeply revealing and thus requires a warrant, drawing on the multi-factor test of Carpenter.

3. Impact

This fractured decision leaves open critical questions for law enforcement, courts, and data custodians:

Are geofence warrants categorically permissible for anonymous location data? If so, when—and under what constraints—does a warrant become necessary once data are traceable to an individual?
What standards of particularity and probable cause will apply to multi-step geofence warrants? Must law enforcement petition a magistrate at each step to justify increasingly intrusive data disclosures?
How will courts apply the good-faith exception in future digital search cases involving novel technologies?

Absent clearer guidance, lower courts will struggle to evaluate warrant applications for emergent surveillance tools, and law enforcement will lack firm constitutional guardrails for digital investigations.

Complex Concepts Simplified

Geofence Warrant: A judicial order directing a service provider to search its records for devices that were within a specified geographic perimeter (“geofence”) during a defined time window.
Location History: A feature on some mobile devices that automatically logs a user’s precise whereabouts (latitude, longitude, and elevation) at short intervals, storing those data on a corporate server.
Third-Party Doctrine: Under Smith and Miller, information voluntarily exposed to a third party generally carries no Fourth Amendment protection, at least for categories of data society has long treated as non-private.
Good-Faith Exception: Even if a search warrant is later found invalid, evidence seized under an officer’s objectively reasonable reliance on that warrant need not be excluded, to avoid penalizing blameless conduct (Leon).
Particularity Requirement: A warrant must clearly describe the place to be searched and the items (or categories of data) to be seized so that officers and magistrates understand its scope.
Probable Cause: A fair probability—supported by facts and circumstances—sufficient to justify a warrant to search a specific place or seize evidence related to a particular crime.

Conclusion

The Fourth Circuit’s en banc decision in United States v. Okello Chatrie leaves the legal community at a crossroads. A unanimous en banc panel agreed that Detective Hylton’s reliance on a magistrate’s warrant was objectively reasonable, saving the geofence warrant under Leon. Yet the split over whether non-anonymous Location History data is a Fourth Amendment “search” underlines the urgent need for clearer constitutional rules in the digital era.

Going forward, magistrates must grapple with the twin imperatives of privacy and public safety when evaluating geofence requests: requiring particularized probable cause for non-anonymous location data while permitting targeted, limited searches of anonymous datasets. Until the Supreme Court or Congress provides definitive answers, district courts and practitioners should follow the narrowest path—scrutinizing geofence warrants for precise time, place, and suspect limits and demanding full transparency about a provider’s anonymization protocols.

United States v. Okello Chatrie thus underscores both the promise and peril of novel surveillance tools. By insisting that constitutional protections keep pace with technological change, the judiciary will best preserve the “privacies of life” the Fourth Amendment was designed to secure.