A modern tool in police investigations, “geofence warrants”, were challenged in Chatrie v. United States, 609 U.S., No. 25-112 (2026). The Supreme Court’s 6-3 decision, written by Justice Kagan, limits law enforcement’s ability to obtain an individual’s cell phone records, specifically individual’s cell phone location history data from technology companies. A geofence warrant was the subject of this decision, which is a warrant compelling a company to produce cell phone location history within a “geofence” (i.e., a virtual perimeter) around a crime scene.

The Court concluded that collecting cell phone location history data like this is considered a “search” under the Fourth Amendment. Therefore, law enforcement must have probable cause to obtain a warrant before compelling companies to turn over this information. The Court reasoned that individuals have a reasonable expectation of privacy in their cell phone location records. This decision impacts a wide range of individuals and entities:

• law enforcement who use this information in hard-to-solve crimes,
• organizations that collect and store information requested by law enforcement, and
• more broadly, cell phone users who share location information with those companies.

Factual Background

In 2019, a man robbed a credit union in Virginia. As part of the investigation, the police discovered the robber was talking on a cell phone as he approached the crime scene. With this information, law enforcement sought a geofence warrant requesting cell phone location data within a perimeter of the crime scene from Google. Specifically, the warrant outlined a three-step process the officers would use to obtain the desired information:

• Step 1: Google gives law enforcement anonymized location data for all cell phones used within a time window of 30 minutes before and after the crime.
• Step 2: Police officers compare the time-stamped locations in the list against the known time and location information relating to the crime. Then, Google provides additional anonymized information about the location of the users from the narrowed list, over a two-hour period.
• Step 3: Again, police compare the additional information on travel and time to the known information specific to this crime. Once they construct an even narrower, and final list, Google supplies them with the names and phone numbers for each user.

Using the three-step process, officers narrowed the list from 19 users identified within the initial geofence to nine users. At the final step, Google provided identifying information for three users, with Petitioner, Okello Chatrie (“Chatrie”), being one of those individuals. His location data showed that he entered the geofenced area 10 minutes before the robbery and headed towards a residential area immediately after the robbery. When Chatrie was charged with robbery and firearm offenses, he challenged the cell phone location history data that the police received from Google. He argued that:

• obtaining cell phone location information from Google was a search under the Fourth Amendment, and
• the warrant authorizing the search was invalid.

The Supreme Court granted certiorari to answer the question of whether the police violated the Fourth Amendment by obtaining his cell phone location data.

The Fourth Amendment

 The Fourth Amendment protects people from unreasonable searches and seizures of their persons, houses, papers and effects and was designed, in part the Court explains, to constrain police surveillance. As technology advances, however, the government’s ability to intrude on private life has expanded. The concern here is that access to cell phone location data would allow the government to examine an individual’s movements in both public and private spaces. Accordingly, the Court must ensure that Fourth Amendment protections for individual privacy continue to apply in an increasingly technological society.

Supreme Court’s Analysis

 To support the decision, the Court compares cell phone location history to other private materials such as emails, documents, photos, calendars and even a personal journal. The Court uses this to show that a person reasonably understands that this type of information is personal, undermining the government’s argument that by authorizing Google to collect, retain and use location information, a user has relinquished their legitimate expectation of privacy. Even though the government emphasizes that most smartphone functions require some kind of opt-in feature, the Court minimizes this by claiming that it would be unrealistic to expect that people carry their phones without fully using them. The Court also emphasizes that Google:

• repeatedly prompts users to enable location history,
• warns that certain services may not function properly unless they do so and
• does not clearly explain how often that information may be shared.

The government also argues that brief access to location history is not a Fourth Amendment search. However, the Court disagrees, finding that the Fourth Amendment applies regardless of duration.

Justice Kagan’s majority opinion looked to the Court’s previous decision in Carpenter v. United States, 585 U.S. 296 (2018), where it held that people have an expectation of privacy in their cell-site records such that the government cannot access that information without probable cause. The Carpenter decision reasoned that because humans are so dependent on cell phones, they compulsively carry them everywhere. If governments could easily obtain this information, they would have access to nearly all of a user’s movements.

Cell-site location information (“CSLI”), the information at issue in Carpenter, allows law enforcement to “travel back in time” so that once they find a suspect, they can look retrospectively at their prior movements, which effectively allows the government to retrace where the person has been. The challenged location history data at issue in Chatrie presents an even greater privacy concern than CSLI because it is a more precise measure that identifies a smaller location radius and even records a user’s elevation.

The Court’s Decision Simplified

1. Did law enforcement officials conduct a search under the Fourth Amendment when they acquired Chatrie’s location data from Google?

 Yes, this was a search under the Fourth Amendment. The Court found that an individual has a legitimate expectation of privacy over their cell phone location data. It does not matter how short the period being investigated is or whether a third-party company hands over the information. All individuals have a reasonable expectation of privacy over their physical movements, whether in public or not.

2. Did the multi-step geofence warrant issued here make the search reasonable?

 Because this search falls under the Fourth Amendment, the search cannot be “unreasonable.” Chatrie challenges the multi-step warrant on grounds that each step is unconstitutional, arguing:

• The first step allows law enforcement to serve a general warrant that is insufficiently described and lacks probable cause.
• The second and third steps give too much authority to the police to define the scope of the search and probable cause.

The government argues that probable cause existed since it was legitimate to believe that Google had information about the crime, and that it is reasonable to give law enforcement this degree of discretion. However, the Court remands this question to the Court of Appeals to decide in accordance with the Fourth Amendment and principles outlined in this decision.

Takeaways:

• Procedurally, law enforcement agencies, government entities and municipalities seeking cell phone location history must first obtain a warrant supported by probable cause and described with sufficient specificity before accessing location history data from a third party.
• The Court did not decide whether multi-step warrants are enough to meet the necessary reasonableness standards but remanded that question to the lower courts. Departments that use or are considering geofence warrants should keep in mind that their legal future remains uncertain. However, in the meantime, agencies that make use of these multi-step geofence warrants should limit officer discretion by creating clear criteria for how officers will narrow the lists in between stages.
• In the future, multi-step warrants are likely to be challenged under the Fourth Amendment. However, just because they are likely to be challenged does not mean that they are going to be undone. Instead, each warrant’s specific terms will need to be investigated in its individual context for reasonableness.

For questions about Fourth Amendment issues affecting law enforcement and municipalities, please contact Anthony G. Becknek, Lily C. McKay or another member of Klein, Thorpe & Jenkins’ Municipal Law Practice Group.

Authored by:

Jena Kaddoura (unpictured)