[This is a guest post by Rudraksh Lakra.]
On January 16, 2026, the Supreme Court of the United States (“SCOTUS”) agreed to review the constitutionality of geofence warrants in Chatrie v. United States (“Chatrie”). A geofence warrant allows law enforcement to collect data from devices within a specified geographic area, known as a geofence, during a designated time period. The petitioner challenged a decision of the Court of Appeals for the Fourth Circuit, which held that the government’s use of a geofence warrant did not constitute a “search” under the Fourth Amendment, as well as the Fourth Circuit’s subsequent en banc decision reaffirming that ruling.
This blog examines the constitutionality of geofence warrants under the Fourth Amendment in Chatrie. The discussion proceeds in three parts. First, it reflects on the rise of digital surveillance and situates geofence warrants within this broader context, explaining how they operate in practice.. Second, it outlines and analyzes the arguments advanced by the government and the petitioner. Third, it situates these arguments within the SCOTUS decision in Carpenter v. United States (2018) (“Carpenter”), examining whether that case should be read narrowly or as signalling a broader shift in digital privacy jurisprudence.
Background
Since the advent of the internet, the digital traces individuals leave behind have become increasingly detailed and enduring, a trend intensified by smartphones, wearable technologies, and the expansion of Internet of Things ecosystems. In this environment, the accumulation of vast repositories of data has become nearly inevitable. The granularity and scale of such data challenge conventional understandings of privacy and what constitutes a reasonable expectation of privacy. Large datasets enable sophisticated data mining and algorithmic analysis, allowing insights to be drawn that would be difficult, if not impossible, to derive from isolated data points. These concerns are amplified when multiple datasets are combined, revealing patterns and inferences far removed from the purposes for which the data was originally collected.
In this context, one of the key defences of large-scale surveillance programmes has been that, while the initial sweep may be broad, the eventual search is narrow, targeted and backed by safegaurds (see ECtHR, Big Brother Watch v. UK and Centrum för Rättvisa v. Sweden). Under this logic, the mere existence of large databases is treated as unproblematic, with constitutional scrutiny directed primarily at the results of a search rather than the scope of the data sweep itself.
Geofence warrants, sometimes referred to as reverse location warrants, raise even more serious constitutional concerns because they depart from this model. Unlike traditional warrants, they are not tied at the outset to a known individual, device, or specific property. Instead, they authorise the collection of location data for all devices within a defined geographic area during a specified time window. Only after this broad collection does law enforcement sift through the data to identify particular individuals of interest. This inversion of the investigative process, in which suspicion follows rather than precedes data collection, raises profound constitutional concerns.
These Geofence warrants requests are typically directed at major technology companies that store large amounts of user data through services such as mobile operating systems, email platforms, and cloud storage. In the United States, both state and federal law enforcement agencies have increasingly relied on private technology companies such as Google, Apple, and Microsoft for user data in criminal investigations. Google receives the vast majority of geofence warrants because it maintains extensive historical location records through its “location history” feature, which are stored in a database known as Sensorvault. Between 2017 and 2018, Google experienced a 1,500% increase in requests. By 2021, geofence warrants constituted 25% of all warrants submitted to Google.
The SCOTUS’s review in Chatrie marks its first opportunity to directly address geofence warrants, and federal Courts of appeals are currently divided on their constitutionality. Before examining the constitutional issues, it is important to understand how geofence warrants function in practice. Geofence warrants generally unfold in a three-step process. For instance, in Chatrie, the process involved:
- Step 1 – Initial Geofence Data: Law enforcement obtained a geofence warrant requiring Google to identify all devices detected within a 300-meter radius of the bank during a one-hour period. To comply with this request, Google had to search through its entire location database. The information provided at this stage was anonymized.
- Step 2 – Expanded Location Data: After identifying a subset of potentially relevant nine accounts, Google provided additional anonymized location data covering a longer, two-hour period. At this stage, the geographic limits were lifted, meaning the full location history of those accounts during the two-hour window was disclosed. This data is also anonymized.
- Step 3 – Deanonymization: At the third step, after law enforcement reviewed the additional location data and narrowed the list of relevant devices to three, Google provided identifying information for specific accounts, including usernames and email addresses.
Importantly, the warrant is only taken at the first stage, meaning law enforcement does not seek a separate warrant before obtaining identifying information in the second and third stages.
Fourth Amendment Knots
The government contended that the petitioner lacked a reasonable expectation of privacy because he voluntarily shared his cellphone location data with Google by opting into the location history service. By doing so, the government contended, he relinquished any Fourth Amendment protection in that information under the third-party doctrine, which generally holds that individuals have no constitutional privacy interest in data they knowingly disclose to a third party. Framed this way, the case becomes less about surveillance and more about assumption of risk in the marketplace. The government attempted to distinguish this case from Carpenter, a decision on which the petitioner heavily relied. In Carpenter, the Supreme Court held that the third-party doctrine did not apply to the government’s extensive and highly detailed collection of historical cell-site location information(“CSLI”), and that obtaining such data constituted a search under the Fourth Amendment.
According to the government, two key differences set this case apart from Carpenter. First, it involved the collection of seven or more days of location data, which the Court described as providing an “intimate window into a person’s life.” By contrast, the geofence warrant here covered a limited geographic area and a short time frame. As a result, the government argued, the warrant did not generate an “all-encompassing record” of the petitioner’s movements or a comparably revealing portrait of his private life. Rather, it simply placed the petitioner near the credit union around the time of the robbery. Second, the government stressed that, unlike the CSLI in Carpenter, Google’s location history data is gathered only when users take the affirmative step of opting into the service.
The petitioner argued that the geofence warrant was inherently unconstitutional. They posited that Carpenter’s reasoning applied squarely to this case. The petitioner emphasized that location history data obtained through a geofence warrant is even more comprehensive than the CSLI at issue in Carpenter. Unlike CSLI, which typically tracks a single individual, geofence warrants enable surveillance of everyone within a defined geographic area. They further highlighted that, by using a geofence warrant, law enforcement can obtain information about all individuals present at sensitive locations such as abortion clinics, political protests, or party conventions at a particular time. Like CSLI, location history data can reveal deeply intimate details about a person’s life. In fact, it is even more invasive, as Google tracks a user’s day-to-day physical movements using GPS, Wi-Fi, mobile networks, and cell tower data at roughly two-minute intervals. Moreover, the petitioner argued that accessing such data is relatively easy and inexpensive for law enforcement, increasing the risk of overuse and abuse.
Alternatively, the petitioner contended that this specific geofence warrant constituted an unlawful search because the government obtained a warrant only for the first stage of the process, but not for the data collection that occurred during the second and third stages.
The petitioner also relied on the decision of the Court of Appeals for the Fifth Circuit in United States v. Smith (2024), which held that geofence warrants are per se unconstitutional. The Court reasoned that the first step of the geofence process requires Google to search through its vast database, reportedly containing location data for over 590 million users, to identify devices present at a particular place and time, even though law enforcement does not yet know, and may never know, whom they are looking for. The Court likened this sweeping search to the “reviled general warrants and writs of assistance” of the colonial era.
The petitioner further argued that the government’s reliance on the third-party doctrine was misplaced for two reasons. First, although Google formally requires users to opt in to location history, the company’s design strongly nudges users toward enabling location tracking. People are repeatedly prompted to grant location access and are told they will get the most out of the app by turning it on. In this environment, “voluntary” disclosure becomes a legal fiction, masking the reality that meaningful participation in digital life often depends on acquiescing to pervasive data collection. Second, the third-party doctrine emerged from 1970s-era cases involving pen registers (Smith v. Maryland) and bank records (United States v. Miller), forms of information that were neither as deeply revealing nor as inseparable from daily life as modern cellphone data. This highlights a broader structural problem: the third-party doctrine has not kept pace with the realities of digital life (see here, here, here, here, here, and here). The doctrine’s underlying assumptions about limited exposure and genuine choice fit uneasily with a world in which participation in social, economic, and civic life increasingly depends on digital services. Seen in this light, the case exposes a deeper tension: whether the Fourth Amendment doctrine will adapt to technologies that make constant data generation functionally unavoidable.
Revisiting Carpenter
At the heart of both the government’s and the petitioner’s claims lies the impact of Carpenter v. United States on Fourth Amendment jurisprudence. The government attempted to confine Carpenter to its facts, portraying it as a narrow decision limited to the long-term collection of historical cell-site location information. On this view, Carpenter is primarily about the duration of surveillance, and therefore does not extend to the shorter time frame involved in this geofence warrant.
This restrictive reading resembles the “mosaic theory” of privacy, which has been widely criticized, even by the scholar most prominently associated with it, Orin S. Kerr. It suggests that privacy concerns arise primarily when the government aggregates large quantities of data over time. However, as the petitioner implicitly argued and as emphasized in the amicus brief filed by Privacy & Surveillance Accountability, Inc., Carpenter is not solely about the duration of surveillance. Rather, it focuses more broadly on the depth, breadth, and revealing nature of the data the government can obtain about an individual, not merely the length of time over which it is collected. In this sense, Carpenter marks a departure from the traditional place- or thing-based focus of SCOTUS Amendment jurisprudence. The decision signals a new kind of expectation of privacy inquiry, one that asks how much the government can learn about a person, regardless of the physical source of the information.
This shift is reinforced by the Court’s use of a contextual, totality-of-the-circumstances analysis. Rather than treating disclosure to a third party as dispositive, Carpenter treats it as only one factor among many in assessing reasonableness. A transformative reading of Carpenter, therefore, would significantly narrow the scope of the third-party doctrine in the digital age and subject large-scale, suspicionless data collection practices such as geofence warrants to meaningful Fourth Amendment scrutiny.
At the same time, even this broader interpretation has limits. The Court emphasized the unique nature of digital data and suggested that heightened protection may be warranted where surveillance reveals the “privacies of life” or involves technologies that have become indispensable to modern existence. Thus, Carpenter may be best understood not as a wholesale abandonment of prior doctrine, but as an equilibrium-adjustment, one that recognizes that certain digital technologies are so pervasive and intrusive that traditional assumptions about voluntariness and exposure no longer hold.
Conclusion
At Stake in Chatrie is whether the Fourth Amendment can meaningfully regulate suspicionless, technology-driven data sweeps that reveal detailed information about where people go, whom they associate with, and what spaces they occupy. A decision that treats geofence warrants as outside the scope of the Fourth Amendment would reinforce the continued dominance of the third-party doctrine and risk normalizing broad digital dragnets as routine tools of investigation.
By contrast, a ruling that views geofence warrants through the lens of Carpenter could mark an important step in adapting constitutional protections to the realities of the digital age. Recognizing that large-scale location data exposes the “privacies of life” would place principled limits on generalized searches and acknowledge that formal notions of consent do not fully capture how modern technologies operate in practice.
The implications would also extend to data privacy standards, everyday law enforcement practices, and the ways in which technology companies collect, store, and respond to requests for user location data. The Court’s reasoning may influence how lower Courts assess other emerging “data scan” techniques, including reverse keyword searches, cell tower dumps, artificial intelligence–driven queries, and other large-scale, algorithmic, or reverse-search methods that rely on bulk data held by private companies.
