Legal Tech • November 2024

Courts Are Split

A look at the constitutionality of geofence warrants.

Written By Pierre Grosdidier

In United States v. Chatrie, the U.S. Court of Appeals for the 4th Circuit held, on basis of the third-party doctrine, that a geofence warrant did not violate the Fourth Amendment’s prohibition against unreasonable searches.¹ A geofence warrant seeks cellphone location history collected and stored by Google at the phone user’s election.² The third-party doctrine holds that a person enjoys no Fourth Amendment protection in information that the person knowingly and voluntarily conveys to a third-party, because the person runs the chance that the latter would communicate it to authorities.³

A robber held up a Virginia credit union and flit with nearly $200,000. Having reached an investigative impasse, authorities served Google with a geofence warrant. Google follows a three-step procedure to respond to these warrants. First, it provides anonymous location information for all users within a designated and relatively narrow geographic area and time window (the geofence). Here, authorities asked for all users located within a 150-meter radius of the credit union and within 30 minutes of the robbery. Next, Google provides additional anonymous location history data outside the geofence, but only for a subset of users identified in the first step. Finally, Google provides the identity of yet another subset of users of particular interest to authorities. The geofence warrant in this case led authorities to three individuals, one of whom was Okello Chatrie, whom authorities indicted.⁴

Chatrie unsuccessfully moved to suppress the warrant’s evidence at trial. He argued on appeal that the warrant that exposed him breached his reasonable expectation of privacy in his location history data and “lacked probable cause and particularity.” The court rejected his arguments and held instead that the third-party doctrine “squarely” governed the case. It held that Chatrie voluntarily exposed his location history data to Google when he “knowingly and voluntarily” enrolled in its service. In doing so, he assumed the risk that Google would convey his data to authorities. Chatrie, therefore, could not have a reasonable expectation of privacy in his data, and authorities did not conduct a Fourth Amendment search when it secured the data from Google.⁵

The court rejected Chartie’s argument that Carpenter v. United States should control the case.⁶ In Carpenter, the U.S. Supreme Court narrowly refused to apply the third-party doctrine to cell site location information (CSLI) because the latter continuously and thoroughly chronicled a person’s physical whereabouts and, therefore, provided an “intimate window into a person’s life.” In this case, authorities only ultimately obtained two hours of Chatrie’s location history data, which essentially amounted to a single trip and was insufficient to intrude into his personal life. Carpenter also held that cellphone users do not affirmatively convey their CSLI to their service providers because cellphones continuously ping cell towers in the background. By contrast, users must personally authorize Google’s location history data service. Thus, Chatrie “knowingly and voluntarily” disclosed his data to Google. Finally, the Supreme Court found in Carpenter that cellphones are “indispensable to participation in modern society.” Here, empirical evidence indicated otherwise: only two thirds of Google users have activated the service despite its benefits.⁷

The U.S. Court of Appeals for the 5th Circuit reached a different result in United States v. Smith.⁸ Authorities nabbed Jamarr Smith and his confederates through a geofence warrant after a robbery. Defendants appealed the trial court’s denial of their motion to suppress. The court found geofence data as potentially invasive of privacy as CSLI data because “even a brief snapshot,” like a visit to a psychiatrist, “can expose highly sensitive information.” It also rejected the third-party doctrine because it found that users can be lured unwittingly into enabling tracking applications and can struggle to disable them.⁹ The court also analogized geofence warrants to the general warrants reviled by the colonist. It noted that Google does not store its location history data on a geographic basis. Therefore, it must search through its entire Sensorvault database to find users responsive to the geofence warrant. This type of broad search, where authorities do not know who they are looking for, and whether they will even find someone, is precisely the type of fishing expedition “categorically prohibited” by the Fourth Amendment.¹⁰ The court nonetheless upheld the warrant in this case on basis of the good faith exception.

PIERRE GROSDIDIER is a litigation attorney in Houston. He is certified in construction law by the Texas Board of Legal Specialization. Grosdidier’s practice also includes data privacy and unauthorized computer access issues and litigation. Prior to practicing law, he worked in the process control industry. Grosdidier holds a Ph.D. from Caltech and a J.D. from the University of Texas. He is a member of the State Bar of Texas, a registered P.E. in Texas (inactive), a member of the Texas Bar Foundation, and a fellow of the American Bar Foundation. Grosdidier was the State Bar of Texas Computer & Technology Section chair for 2022-2023 and was elected medium section representative to the State Bar of Texas for the 2023-2026 term.