The United States Supreme Court has ruled that geofence warrants authorizing law enforcement to search cell phone location history from a crime scene violate the Fourth Amendment to the Constitution of the United States. The sweeping warrants have often been criticized as an unconstitutional dragnet allowing police to collect this information from individuals within a radius of a virtual fence during a specified time frame. The information retrieved is detailed, revealing and more precise than cell site location information or data generated by global navigation satellite systems.

1. Introduction

On June 29, 2026, the Supreme Court of the United States released the ruling in Chatrie v. United States that the use of a geofence warrant by law enforcement to harvest cellphone location data is a search for purposes of the Fourth Amendment. (here) The text of the Fourth Amendment guarantees “[t]he right of the people to be secure […] against unreasonable searches and seizures”. Warrants must be issued based on “probable cause” and must “particularly” describe the place to be searched and the persons or things to be seized. (here) Writing for a 6-3 majority, Justice Elena Kagan held “[a]n individual has a reasonable expectation of privacy in records about his cell phone’s location, and police intrude on that constitutionally protected interest when they demand the information – even though for only a limited time, and from a third-party tech company.”

2. How the Geofence Warrant Worked

On May 20, 2019, at about 4:50 p.m., a man robbed the Call Federal Credit Union in Midlothian, Virginia, making off with $195,000. Police officers who responded to the scene learned from witnesses and surveillance camera footage that the robber had approached the credit union from the vicinity of a nearby church while appearing to talk on a cell phone. But the investigation turned up nothing more and came to a dead end. The police then applied to a magistrate for a geofence warrant directed to Google. A geofence warrant functions as a reverse location warrant that allows law enforcement to search a database for all mobile devices within a specific geographical area within a specific time frame that I discussed in previous posts to On The Wire. (here and here) The warrant application in Chatrie involved a three-step process the police would follow to obtain the location information. The police proposed a geofence of 150 metres surrounding the credit union.

At step one, Google would produce anonymized location data for all cell phones within the geofence in the hour between 4:20 p.m. and 5:20 p.m. At step two, the officers would “attempt to narrow down the list [of devices] by reviewing the time stamped location coordinates for each [device] and comparing that against the known time and location information that is specific to this crime.” For that narrowed list, Google would provide additional (but still anonymized) data – cell phone locations both inside and outside the geofence during a two hour period. At step three, police would again “attempt to narrow down the list by comparing this additional information regarding travel and time against the known time and location information that is specific to this crime.” Google would then release identifying information for each user on the final list including names and phone numbers.

By step three, the list was narrowed to three users. Google responded with their identifying information. One of the three was Okello Chatrie. The location data showed that he entered the geofenced area about ten minutes before the robbery and headed toward a residential neighbourhood immediately after leaving the credit union. A federal grand jury indicted Mr. Chatrie for robbery and related firearms offences. He moved to suppress the information the police had obtained from Google asserting that the acquisition of the data was a Fourth Amendment search authorized by an invalid warrant.

3. Judicial History

On September 17, 2019, the grand jury indicted Mr. Chatrie in the United States District Court for the Eastern District of Virginia on counts of robbery and use of a firearm during a crime of violence. (here) The District Court mainly agreed with his Fourth Amendment analysis on the suppression application but denied the motion because the officers’ reliance on the geofence warrant was not “objectively unreasonable.” The court therefore concluded that the good faith exception to the exclusionary rule permitted admission of the location data. (here) Mr. Chatrie then pleaded guilty to robbery but retained his right to appeal the District Court’s ruling. A divided panel of the United States Court of Appeals, 4th Circuit, affirmed but for different reasons. The majority held the government did not conduct a search and therefore did not need a warrant. Mr. Chatrie “did not have a reasonable expectation of privacy in two hours’ worth of Location History data voluntarily exposed to Google.” (here) The Fourth Circuit granted rehearing en banc and affirmed. (here)

4. In the Supreme Court

The Supreme Court granted certiorari solely on the question whether the police violated the Fourth Amendment in obtaining Mr. Chatrie’s location data, thus declining to consider the exclusionary rule issue. The disputed Fourth Amendment question divided into two parts. First, did the police conduct a search under the Fourth Amendment when they acquired Mr. Chatrie’s location data from Google? The majority concluded they did “because an individual has a legitimate expectation of privacy in his cell phone location data.” Second, did the multi-step geofence warrant make the search reasonable? That question, which requires deciding whether the warrant satisfied the Fourth Amendment’s probable cause and particularity requirements at each stage of the search process, was left to the Court of Appeals to address in the first instance.

Justice Kagan emphasized that the purpose of the Fourth Amendment is “to safeguard the privacy and security of individuals against arbitrary invasions by government officials.” Although the court’s early search doctrine focused on whether law enforcement officials obtained information by physically intruding – that is, trespassing – on private property, the court also concluded in Katz v. United States that “the Fourth Amendment protects people, not places.” (here) The government therefore conducts a search when it invades an area that “an individual seeks to preserve […] as private” and that “expectation of privacy is one that society is prepared to recognize as reasonable.”

In Carpenter v. United States, the court held that law enforcement officials conduct a search for Fourth Amendment purposes when they access cell site location information. (here) Cell site location information can provide a full record of a person’s whereabouts and an intimate window into his or her life. “The resemblances between CSLI and Location History, in their relationship to personal privacy, practically leap off the page,” Justice Kagan said. “Everything Carpenter relied on to find that law enforcement officers conducted a Fourth Amendment search when they accessed wireless carriers’ CSLI records applies as well or better to the police’s accessing of Google’s Location History data.”

Justice Kagan went on to state it does not matter that the police accessed only a short amount of location information. As Justice Sonia Sotomayor said in United States v. Jones, “[E]ven short-term monitoring” of a person’s physical movements can provide “a wealth of detail about an individual” such as trips to “the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, [or] the by-the-hour motel.” (here) And, unlike a GPS device, location history enables the police to focus on precisely those sites to see, in a given time frame, who shows up. Even two hours of location history “allows officers to target one-off events of potential interest: a gun show, say, or a political rally.” Location data “is the automatic price of conventional cell-phone usage.”

5. Conclusion

The Supreme Court has now issued twin rulings in Carpenter and Chatrie rejecting the government’s contention that the third party doctrine governs the acquisition of cell site location information and location history. The court emphasized in Carpenter that cell phone location information is “not truly shared” as cell phones are “indispensable to participation in modern society.” Likewise, in Chatrie, location history is “not truly shared” in the normal sense. ‘The exposure of that information to Google is merely what happens when a user avails himself of one of the services on his cell phone,” Justice Kagan concluded. “Or said a bit differently, it is the automatic price of conventional cell-phone usage – which, just as Carpenter noted, is a ‘pervasive and insistent part of daily life.’  So just as the third-party doctrine did not apply in Carpenter, it does not apply here.”