It’s been a few years since the Supreme Court heard a major Fourth Amendment case. That will change next month when the justices hear oral arguments in Chatrie v. United States on the government’s use of geofencing warrants to obtain a person’s cell phone data. Their ruling could have major implications for how and when police can access Americans’ sensitive personal information in the digital age. It will also provide an important window into how the latest iteration of the Supreme Court thinks about the Fourth Amendment, tech companies, and privacy rights.
This particular case began with a bank robbery in a town outside Richmond, Virginia, in May 2019. Local police officers followed the usual investigative steps but came up short on leads. The following month, one of the detectives sought what is known as a geofencing warrant that required Google to comb through millions of accounts and identify which ones came within a 150-meter radius of the crime scene for an hour around the time of the robbery.
Google is a common target for geofencing requests because of its location-tracking service, unimaginatively named Location History, which more than 500 million users have activated. Location History updates itself roughly every two minutes, effectively creating a comprehensive record of a person’s movements—a literal digital footprint, if you will, albeit one that users can delete.
Since it receives so many requests, Google has developed a multistep process for responding to them. For the first step, the company initially provided a police detective with semi-anonymized data for 19 users within the geofence. The detective then requested additional data on nine of those users for the second step. He “did not explain to Google why he chose these nine accounts, nor did he consult a magistrate [judge],” according to court filings, but Google complied. From there, the detective “requested that Google de-anonymize three of the numbers, again without explaining why or consulting a judge,” which Google agreed to do as the third and final step.
Finally, detectives used the data to identify a local man named Okello Chatrie and obtain a search warrant to search his house. According to the Justice Department, they found “two robbery-style demand notes,” as well as “nearly $100,000 in U.S. currency (including bills wrapped in bands signed by the victim bank teller) and a silver and black 9mm semi-automatic pistol” that looked like the one carried by the bank robber in surveillance footage.
Federal prosecutors charged Chatrie with multiple felonies related to the bank robbery. Ahead of trial, Chatrie and his lawyers asked a judge to exclude any evidence obtained through the geofencing warrant, including what detectives found at Chatrie’s house because of it, on the grounds that it violated his Fourth Amendment protections from unreasonable searches and seizures.
The district court broadly ruled in Chatrie’s favor. For step one—the search warrant to obtain the first 19 accounts—the court held that the government did not have sufficient probable cause to obtain the warrant to geofence those accounts. On the additional searches that narrowed it down to nine users and then three users, the district court also concluded that it had “improperly provided law enforcement and Google with unbridled discretion to decide which accounts will be subject to further intrusions.”
Ultimately, however, the district court applied what is known as the “good-faith exception,” one of the many holes in the Swiss cheese that is the modern Fourth Amendment, to uphold the search. Chatrie entered a conditional plea of guilty while he challenged the geofence warrant’s constitutionality on appeal. He was sentenced to more than 11 years in prison. Chatrie’s next stop, legally speaking, was the Fourth Circuit Court of Appeals, which promptly made a dog’s breakfast of the case.
At first, a divided three-judge panel affirmed the district court’s ruling, but on much different grounds. Two of the judges held that the Fourth Amendment hadn’t been violated at all because Chatrie and other Location History users had voluntarily given their location data to Google. Under the third-party doctrine, a twentieth-century carve-out for warrantless searches, Americans lose the “reasonable expectation of privacy” when they voluntarily hand over personal information to a third party, like a bank or a telecommunications company.
Judge James Wynn, the dissenting judge on the panel, countered by noting that the dispute more closely resembled the 2018 case Carpenter v. United States. In that ruling, the justices had held that cell-site location information, or CSLI, was protected from warrantless searches by the Fourth Amendment. The high court explicitly declined to extend the third-party doctrine to CSLI data in Carpenter because of its intensely personal nature. The Location History data more closely resembled that CSLI data than bank records or records of dialed phone numbers, the dissenting judge argued.
When all 14 Fourth Circuit judges reviewed the panel’s ruling, things only fractured further. The court upheld the panel’s decision, but only because of a 7–7 deadlock. In appeals courts, a tie always goes to the lower court’s decision. Seven of the judges claimed that combing through Google’s Location Services did not count as a Fourth Amendment search at all, while seven concluded that the Fourth Amendment still applied. (Only one of the latter seven judges would have actually declined to apply the good-faith exception and excluded the evidence, however.)
In one of the concurring opinions, a Fourth Circuit judge sounded almost giddy about the potential of geofencing warrants in tracking down suspects. “Officers were out of traditional leads,” Judge J. Harvey Wilkinson, who was part of the original panel majority, claimed. “Only the geofence warrant eventually allowed police to track Chatrie down and restore a sense of resolution to the community. Without geofence location data, crimes even more serious than this one will escape detection.”
Others were less enthusiastic. “The surveillance technologies at issue in this case—the very same ones that seem to thrill my colleagues who join Judge Wilkinson’s separate opinion—would have been unimaginable to the Founders,” Wynn argued, this time with additional colleagues supporting him. “Yet, in Carpenter v. United States, our Supreme Court rightly recognized that the principles enshrined in the Fourth Amendment do not wither in the face of advancing technologies. Rather, they must be vigorously protected from ever-expanding methods of government intrusion.”
Different appellate courts have reached other conclusions than the Fourth Circuit. The Fifth Circuit Court of Appeals, which covers Texas and neighboring states, held in a 2024 case that geofence warrants violated the Fourth Amendment. “While it is true that geofences tend to be limited temporally, the potential intrusiveness of even a snapshot of precise location data should not be understated,” a three-judge panel noted.
Fourth Circuit judges had concluded that because Location History users technically must opt in to the service, Carpenter did not apply for third-party doctrine purposes. (As the justices recognized in Carpenter, one only voluntarily agrees to give up their CSLI data in the sense that they agree to own a cell phone at all.) Their Fifth Circuit colleagues took a more grounded view. “As anyone with a smartphone can attest, electronic opt-in processes are hardly informed and, in many instances, may not even be voluntary,” Judge Carolyn King wrote for the court.
The Supreme Court took up Chatrie v. United States in an apparent bid to solve the circuit split. In its court filings, the Justice Department argued—not unsurprisingly—that half of the Fourth Circuit got it right: The government hadn’t conducted a “‘search’ within the meaning of the Fourth Amendment,” the third-party doctrine overcame Chatrie’s reasonable expectation of privacy, and he had opted in to Location History anyway. Oh, and even if it was a search, the good-faith exception still applied, the department claimed.
Chatrie, on the other hand, described the original warrant as a “general warrant,” a type of overly broad search warrant that was detested by the Constitution’s Framers as an abuse of power by British officials. The Fourth Amendment’s requirements that search warrants must “particularly describ[e] the place to be searched, and the persons or things to be seized” is considered to have abolished the practice.
To that end, Chatrie argued that the warrant failed the Fourth Amendment’s particularity requirement by forcing Google to search all 500 million Location History accounts. “Indeed, if this warrant’s reference to ‘Google’ satisfies the Fourth Amendment, absurd consequences would follow,” Chatrie warned. “Suppose the government obtained probable cause that someone’s Gmail account contained an incriminating communication. Under the government’s theory, the government could obtain a single warrant identifying ‘Google’ as the ‘place’ to be searched and then search everyone’s Gmail accounts for the incriminating communication. That cannot be right.”
Whether the justices will agree with that assessment isn’t clear. Carpenter, the last major case on this front, was decided in 2018. Three new justices—Brett Kavanaugh, Amy Coney Barrett, and Ketanji Brown Jackson—have joined the court since then. Barrett’s perspective will be particularly important because she replaced Ruth Bader Ginsburg, who was in the Carpenter majority.
At the same time, even the dividing lines in Carpenter might be a misleading road map of how the justices will decide this case. In his dissent from that ruling, for example, Justice Neil Gorsuch laid out a Fourth Amendment approach that does not neatly map onto the court’s usual ideological divide. First, he argued that the Supreme Court had strayed too far from what he saw as a properly property-based understanding of the Fourth Amendment when it adopted a “reasonable expectation of privacy” standard in the 1960s. That standard, laid out in Katz v. United States, was a major development of the Warren court’s liberal jurisprudence.
Abandoning Katz, taken on its own, might send chills down the average liberal’s spine. But Gorsuch went on to argue that his property-based approach, which he described as the “traditional” one, would also demolish the third-party doctrine that fails to protect digital records. “These ancient principles may help us address modern data cases too,” he indicated. “Just because you entrust your data—in some cases, your modern-day papers and effects—to a third party may not mean you lose any Fourth Amendment interest in its contents.”
Gorsuch declined to side with Carpenter himself in that case because the defendant had not made a property-based Fourth Amendment argument during his appeal. Chatrie and his lawyers took the hint, however. While urging the court to take up the case, they took special care to note that they had preserved this Gorsuch-friendly argument in the lower courts. (They raised the privacy-based one, as well, to cover all bases.) The facts are an even better fit than in Carpenter, too: Chatrie, like all Google users, had direct control over his data at all times, which would support the property-based approach.
Some of the court’s liberal members, while not abandoning Katz, have expressed misgivings about the third-party doctrine, as well. In a 2012 case, Justice Sonia Sotomayor wrote in a concurring opinion that it “may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties.” This approach, she argued, “is ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks.”
Other justices have signaled a more restrictive approach. In a separate dissenting opinion, Justice Clarence Thomas also called for Katz to be overturned but indicated that his narrower, property-first interpretation would be more favorable to law enforcement than what Americans currently know and enjoy. He would have ruled against Carpenter because, in his view, the Founders “would not recognize the court’s ‘warrant requirement’” in this context and the common law “did not limit the government’s authority to subpoena third parties.”
“In several recent decisions, this Court has declined to apply the Katz test because it threatened to narrow the original scope of the Fourth Amendment,” Thomas wrote in his Carpenter dissent. “But as today’s decision demonstrates, Katz can also be invoked to expand the Fourth Amendment beyond its original scope. This Court should not tolerate errors in either direction.”
If the court sides with Chatrie, the justices will be putting guardrails on an increasingly common (and far from foolproof) tool for law enforcement agencies to identify suspects. A ruling in the government’s favor will likely lead to geofencing warrants becoming much more widespread. How the justices decide the case—and what they say about the court’s Fourth Amendment precedents along the way—may prove to be just as important as the result itself. Americans will get their first glimpse into the justices’ thinking at oral arguments in April.
