Supreme Court agrees to hear a Fourth Amendment case regarding geofence warrants

The Fourth Amendment protects people from “unreasonable searches and seizures” by the government. Interpreting that protection in light of evolving technology often leads to novel constitutional questions. On Jan. 16, the Supreme Court agreed to consider one such question, granting a petition to hear a case involving the constitutionality of geofence warrants. Argument in the case, Chatrie v. U.S., will likely be scheduled for the spring, with a decision expected by early summer.

What are geofence warrants?

Geofence warrants require a company—often Google—to turn over information regarding the devices that it tracked within a targeted area over a time period of interest. As the supplier of the Android operating system and of apps like Google Maps that run on both iPhones and Android devices, Google has access to an enormous amount of location data. Until at least late 2023, Google stored this information in a centralized repository called Sensorvault, though in December 2023, the company announced it would start migrating the data to people’s personal devices. Whether and to what extent that migration has occurred is difficult to determine.

In response to the rapid growth in the use of geofence warrants by law enforcement starting in the late 2010s, Google developed a multistep process for responding to them. Initially, law enforcement provides Google, via the warrant, geofence information specifying a window in space and time associated with a crime. Google responds by providing the location history for devices it tracked within the geofence. In this initial response, the devices are “de-identified,” so that while law enforcement receives detailed location information regarding the tracked devices, each device is identified only by a number that (in theory, but not necessarily in practice) does not reveal the identity of the device owner.

After analyzing the tracking data, law enforcement can narrow the focus to particular devices of interest and can order Google to provide location data for those devices outside the time and location of the geofence. As a final step, law enforcement can order Google to de-identify devices by providing the associated names or email addresses.

The Chatrie case

Chatrie v. U.S. arose from a credit union robbery in Virginia in 2019. Using a geofence warrant, law enforcement identified Okello Chatrie as a suspect and charged him with several federal crimes.  In the subsequent proceeding in a Virginia federal court, Chatrie sought to suppress the evidence from the geofence warrant, arguing that it violated the Fourth Amendment. The district court concluded that “because the Government Lacked Particularized Probable Cause as to Every Google User in the Geofence,” the warrant was indeed unconstitutional. However, the court declined to suppress the evidence, citing the “good faith” exception.

Normally, under the “exclusionary rule,” evidence obtained through a search that violates the Fourth Amendment cannot be used at trial. But there is an exception recognized by the Supreme Court in 1984: If law enforcement conducts an unconstitutional search on the good faith belief that the search is not unconstitutional, a court can permit the evidence to be used at trial despite the violation.

After failing to obtain suppression of the evidence at the district court, Chatrie appealed to the Fourth Circuit, which handles most appeals from federal district courts in Virginia, West Virginia, and the Carolinas. In July 2024, a three-judge panel issued a 2-1 decision agreeing with the district court that the evidence should not be suppressed but citing a different reason: “Chatrie did not have a reasonable expectation of privacy in two hours’ worth of Location History data voluntarily exposed to Google. So the government did not conduct a search when it obtained this information from Google.” Under this reasoning, since there was no “search,” there was no Fourth Amendment violation.

Chatrie then asked for an “en banc” re-hearing before the full Fourth Circuit, which in April 2025 issued an unsigned, one-sentence opinion joined by 14 of the 15 judges and affirming the district court’s decision to deny suppression of the geofence evidence. That decision was accompanied by eight concurring opinions and a single dissent that collectively spanned over 100 pages. In July 2025, Chatrie submitted the petition that the Supreme Court has now granted.

A fractured landscape

As if the collection of district and circuit court opinions in Chatrie weren’t complicated enough, courts in other jurisdictions have adopted different approaches to the question of geofence warrant constitutionality. In 2024, the Fifth Circuit, which covers Texas, Louisiana, and Mississippi, concluded in U.S. v. Smith that geofence warrants “are modern-day general warrants and are unconstitutional under the Fourth Amendment.” The Fifth Circuit nonetheless invoked the good faith exception, allowing the evidence from the geofence warrant at issue to be used.

Additionally, in April 2025, the Texas Court of Criminal Appeals—the state’s highest criminal court—ruled in Wells v. State that “use of the geofence warrant in this case to obtain location history data did not violate the Fourth Amendment.” This creates an odd situation where geofence warrants are now presumptively constitutional in Texas state courts, but not in Texas federal courts.

Opt-in location data and an expectation of privacy

The arguments before the Supreme Court will focus on the question of whether people have a reasonable expectation of privacy in the location history data collected by Google—and by implication by other app providers as well.

Under the third-party doctrine, which was articulated half a century ago in a very different technological environment, a person does not have a reasonable expectation of privacy in information voluntarily conveyed to a third party. The government can thus obtain that information directly from the third party without running afoul of the Fourth Amendment.

But the contemporary scope of the third-party doctrine is unclear. In 2018, in Carpenter v. U.S., the Supreme Court ruled that information maintained by mobile network providers regarding which cell towers their subscribers’ phones were connected to does not fall under the third-party doctrine. If the government wants cell site information, it needs a warrant. Carpenter left open the question of Fourth Amendment protections for other forms of location data collected by mobile phones and other personal electronic devices.

While the Supreme Court argument is a few months away, key aspects of the parties’ positions are presented in the petition and the government’s response. Chatrie underscores that Google’s location data, because they are based on signals from GPS satellites and nearby Wi-Fi hotspots, are far more precise than the cell site data at issue in Carpenter. Chatrie argues that a warrant should certainly be required to obtain location data that are substantially more accurate than that considered in Carpenter. Chatrie also explains that while prosecutors in Carpenter obtained location data for a handful of mobile phones, a geofence warrant is even more invasive as it seeks location data for all devices in the geofence.

The government argues that Carpenter is inapplicable to geofence warrants. The government points out that unlike cell site data, which are collected automatically when a phone connects to a cell network, Google’s location data are opt-in. The government invokes the third-party doctrine, arguing that Chatrie “voluntarily shared his cellphone location with Google by opting in to the Location History service, thus relinquishing any privacy right in that information.” The government also underscores that the short time window and very limited physical dimensions of a geofence warrant distinguish it from the multi-day, large-area nature of the data at issue in Carpenter.

The problems with the good faith exception

Regardless of whether the Supreme Court ends up siding with Chatrie or the government, a clear ruling can help ensure that future geofence cases avoid the concerning consequences of the good faith exception. Under that exception, as occurred in the Fifth Circuit in U.S. v. Smith and (up until now) in the Fourth Circuit in Chatrie, defendants can be prosecuted using evidence that courts expressly conclude was collected in violation of their constitutional rights.

In a recent law review article in the Georgetown Law Journal, Matthew Tokson and Michael Gentithes performed an empirical study showing (generally, not limited to cases specific to geofence warrants) that “courts frequently employ [the good faith exception] to avoid substantive constitutional rulings.” Courts that invoke the good faith exception can choose to completely sidestep the question of constitutionality, since resolving that question will have no effect on the admissibility of the contested evidence. This leaves key constitutional questions unresolved, even as the number of cases raising them accumulates. The Supreme Court ruling in Chatrie has the potential to eliminate or—if the ruling’s scope is unclear—at least reduce use by future courts of the good faith exception for geofence warrants.

Location tracking and the broader app ecosystem

It might be tempting to conclude that the entire geofence constitutionality question will become largely moot if Google does indeed complete its announced plan to migrate location data storage to personal devices. But there are many other companies that also collect and centrally store location data at least sporadically, and potentially constantly.

Consider, for example, providers of apps for fitness monitoring, tracking the location of family and friends, rideshare and food delivery services, and social media posts that include location tags. As long as location tracking data exist in the hands of third parties, important questions of the associated Fourth Amendment protections will persist. And hopefully the court will consider that, while in some purely technical sense location data are “opt-in,” in a practical sense, engaging in contemporary society requires not only a mobile phone, but also the use of apps that, in order to function, will sometimes need to collect location data.