For nearly a century, the Supreme Court has wrestled with the effects of technology on the privacy interests protected by the Fourth Amendment. That Amendment prohibits unreasonable searches or seizures of persons, houses, papers, and effects. Yet it is undeniable that technological advances enable the police to pry into formerly private areas in ways unimaginable to the drafters of the Bill of Rights. Views of private property from airplanes and helicopters, electronic surveillance of telephone calls, use of infrared imaging to probe the interiors of buildings, and GPS tracking of motor vehicles, allow the government to acquire private information without the type of physical search that would have been familiar to the framers in the late eighteenth century.
In a line of decisions, the Supreme Court has updated the Fourth Amendment to limit unrestrained police searches that draw on new technologies. The Court has a particular romance with cell phones, consistently finding privacy interests in the vast amount of information accessible through smart phones. This week’s decision in Chatrie v. United States continues that trend. Once again, the Supreme Court held that the Fourth Amendment requires a reasonable search, and generally requires a warrant, when the government seeks to compel the production of information from a service provider about an individual’s location generated by his phone.
The decision in Chatrie is narrow and incremental, but the stakes were high. If the Court had declined to find a Fourth Amendment search, it would have opened the door to potential government surveillance of individuals’ locations as tracked by their phones without any judicial oversight. Given the near-ubiquitous use of smart phones and location-tracking apps, the government’s proposed rule — that short-term acquisition of location history did not implicate the Fourth Amendment protections — had enormous and ominous consequences. The Court rejected that concept of a Fourth-Amendment-free zone by finding that, consistent with earlier cases, individuals have a reasonable expectation of privacy about their location when tracked by their cell phone.
But the Court stopped well short of saying whether any judicial warrant could issue for “geofence” information and, if so, what the warrant had to provide. Chatrie thus stands as an important but narrow reaffirmation of the Court’s determination not to let technology overwhelm all privacy expectations in the digital age. The next shoes to drop will come as the lower courts work out the details. Those courts will have to strike the balance between law enforcement needs and privacy interests in the first instance, before the issues inevitably return to the Supreme Court.
The facts. Chatrie involved a characteristic use of a geofence warrant seeking location-history information: trying to identify suspects for a crime. At the time of the events at issue, a geofence warrant allowed the government to acquire information from Google about many of the cell phones present in a particular location.
In 2019, law enforcement was struggling to solve a credit union robbery in a rural Virginia community, despite surveillance footage showing the robber approaching from a church and heading towards the credit union while talking on a cell phone. The government obtained from a state court judge a search warrant issued to Google that allowed the government to proceed in three steps. First, the warrant required Google to provide anonymized information about the location of all phones in its database within a 150-meter radius of the credit union, in a one-hour period surrounding the time of the robbery. In a second step, the warrant allowed the government to expand the scope of the search for a subset of the phones to track the phones’ movements over a two-hour period, with a geographical sweep that reached beyond the virtual “fence.” In a third step, the government could require Google to provide the identities of a limited number of phone users tracked in the second step. The execution of the warrant ultimately allowed the police to identify and then apprehend Okello Chatrie.
The Court’s opinion. In an opinion by Justice Elena Kagan, the Supreme Court held that the acquisition of location history information from Google constituted a Fourth Amendment search. The Court used the “expectation of privacy” framework first announced by the Court in its 1967 landmark decision Katz v. United States. In that case, the Court held that the Fourth Amendment protects against not only physical invasions of property to acquire information, but also the use of technology to infringe a “legitimate expectation of privacy” — there, the conversational privacy of a caller using a phone booth. Katz has endured heavy criticism for turning on the Justices’ subjective intuitions about privacy, rather than any objective test. But Katz has the benefit of allowing the Court to recognize Fourth Amendment protections for government behavior that would otherwise seem to be arbitrary invasions of privacy, such as wiretapping. Katz thus allowed the Fourth Amendment to provide significant protection against pervasive government surveillance despite technological advances that allowed non-trespassory searches.
In Chatrie, the Court extended that protection by holding that a geofence warrant seeking location history for a short period of time and limited spatial reach constitutes a Fourth Amendment search. The Court relied heavily on its 2018 decision in Carpenter v. United States. That case involved the government’s use of a court order to a cell phone provider to obtain cell site location information (CSLI) — that is, a record of the cell towers to which a particular customer’s phone connected. Justice Kagan treated the application of Carpenter to the government’s request for Google’s location history in a geofence warrant as an easy extension of precedent. In her view, Google’s location history information shares the essential characteristics of CSLI and thus warranted the same treatment under the Fourth Amendment.
Justice Kagan’s opinion was joined by the Chief Justice, Justice Sotomayor, Justice Jackson, and Justice Kavanaugh. Justice Gorsuch concurred, but he would have analyzed the case under a property theory that treated the location history as the user’s property even though located on Google’s servers. Meanwhile, Justice Alito, joined by Justice Thomas and in part by Justice Barrett, dissented. Justice Alito sounded the alarm bell that the Court’s decision would “send seismic waves through our Fourth Amendment doctrine,” and would “unleash … [an] upheaval in Fourth Amendment law,” but that apocalyptic prediction seems overblown.
Implications of Chatrie. The Court’s decision is primarily a modest and incremental expansion of Carpenter. The Court removed the temporal limit in Carpenter itself, which involved court orders seeking seven days and 127 days of CSLI. In Carpenter, the Court said only that the acquisition of seven days of CSLI was a search, leaving open whether requests for shorter periods might not be a search (see footnote 3). Here, the Court erased that limitation, finding it inconsistent with the underlying privacy interests in an individual’s location and entailing unworkable line-drawing exercises. First, Justice Kagan observed that highly sensitive personal information can be gleaned from even small periods of location history. She illustrated the point by referring to trips to “the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, [and] the by-the-hour motel.” Beyond that, she noted that any durational limit on when the Fourth Amendment kicks in would allow the government to target particular activities such as “a gun show” or “a political rally” without any oversight or restraint. That degree of government intrusiveness was a bridge too far. As for workability, the Court noted that allowing the government a free shot at short periods of location history opened up a classic slippery slope issue. For instance, is a four-hour period of location history a search? If so, what about two consecutive two-hour periods separated by a fifteen-minute break? No obvious metric would answer those questions, leaving state and federal courts, citizens, and cops in the dark.
The Court’s rejection of the government’s efforts to distinguish Carpenter also avoided uncomfortable questions about the privacy of information stored in the cloud. The government argued that unlike the automatically and inevitably generated records of CSLI in Carpenter, Chatrie and other Google users had to voluntarily opt in to location history, and many users do not do so. Thus, the government argued, unlike the indispensable use of cell phones, a user’s consent for Google to collect and store location history reflected a voluntary decision. But the rationale of that argument could expand to Google calendars, documents, and even email, and the Court wisely declined to distinguish location history from CSLI on that basis. En route to that conclusion, the Court cast a skeptical eye on how voluntary it really is for a user to opt into location history, suggesting that Google’s marketing tactics made user choice somewhat illusory. The Court’s questioning of how voluntary it is for users to click terms of service without reading or understanding the fine print may have significant implications going forward in a variety of areas of law (for readers interested in that element, see pages 26-27).
Limits on Chatrie. While the Court incrementally expanded Carpenter to cover geofence information, it stopped short of determining whether the warrant in this case was valid. As the Court noted, the government and Google had evolved a unique three-step process for geofence warrants. Although the parties extensively briefed whether the warrant was valid at any of those three steps, the Court sidestepped those issues and sent them back to the Fourth Circuit for further review. That remand leaves for another day the potentially most explosive contentions — and seems to leave intact the Fifth Circuit’s view that geofence warrants are “modern-day general warrants” and thus categorically unconstitutional.
Chatrie had similarly argued that any geofence warrant is a “general warrant” – a type of unbounded and nonspecific authorization to search that the Founders “reviled” as the quintessential abusive search. In Chatrie’s view, the execution of a geofence warrant required Google, acting as the government’s agent, to search all of the 500 million users in its location history database to see which phones were inside the fence. Chatrie compared that search to a warrant allowing the police to open all safe deposit boxes at a bank based on suspicion that one of them held contraband, or a warrant to search all apartments in a complex based on probable cause that a drug dealer had his wares in one of them.
If that contention were accepted, it would invalidate not only geofence warrants, but a variety of other types of warrants that involve searching troves of digital data to identify particular individuals within the database. It would seemingly knock out “tower dumps” where the police acquire CSLI for all of the phones that connected to a particular tower at the time of a crime, such a murder, burglary, or rape. And it would invalidate other “reverse searches,” such as where the police ask Google to review its search history database for queries about a fast-acting poison in the wake of a murder by poison, or how to hide a body from the police, or how to conceal an arson. Those searches raise difficult and provocative questions, but the Court gave no signal about its answer.
Chatrie also challenged the second and third steps of the geofence warrant, which allowed the government — with scant criteria specified in the warrant — to expand the scope of the information Google had to produce outside the boundaries of the 150-meter fence and for an additional hour of location information. Justice Jackson, joined by Justice Sotomayor, wrote a separate concurrence to say that those expansions violated the Fourth Amendment by offloading a task that a neutral magistrate should perform and giving the government license to search in its unguided discretion. But the majority declined to reach those issues in the first instance, which had not been resolved by the court of appeals.
Takeways. Chatrie continues the Court’s journey to update the Fourth Amendment’s protections to keep pace with law enforcement’s expanding use of technology to acquire information. Perhaps the most important message from Chatrie is that a majority of the Court is unwilling to give the government a “virtual panopticon” with unlimited potential to “scrutinize its citizen’s activities.”* That position furthers the Court’s long-established understanding of the Fourth Amendment’s purpose — “to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials” and “to place obstacles in the way of a too permeating police surveillance.” Those insights — and the Court’s determination to be guided by the Fourth Amendment’s purpose rather than musty and obscure eighteenth century doctrines — is perhaps the most important message of the decision.
But the mapping of this field remains a work in progress. The Court did not, here or in Carpenter, fully explain why the government’s acquisition of bank records or dialed phone numbers from businesses is not a search, while the acquisition of location history from Google is. Under the “third-party doctrine,” obtaining information about an individual from a third-party business, such as a bank, does not constitute a Fourth Amendment search. Carpenter and Chatrie carve out a category of information from that rule but the scope of the exception (or even whether it is an exception) is a work in progress. At least for email, one court of appeals readily distinguished the third-party doctrine. In contrast, Justice Gorsuch would remodel Fourth Amendment law wholesale by overturning Katz and the third-party doctrine, and make everything turn on property law. But Chatrie is a clear sign that the Court’s majority is not anxious to join him. Similarly, Chatrie tells us nothing about whether the government, like any private party, can enter private markets to purchase information from database brokers that might reveal as much as, or even far more, than warrants to Google or similar entities. Those threats to privacy may escape Fourth Amendment scrutiny unless there are dramatic changes to the conception of the law.
Those who would look to the Constitution to protect the most sensitive of privacy interests might take heart from Chatrie, but hopes that the Court will do all of the work may be misplaced. Chatrie may affect a limited universe of information. Chatrie, like most of the Supreme Court’s recent forays into the intersection of the Fourth Amendment and technology, comes many years after the underlying searches (seven years in both Carpenter and Chatrie) . Underscoring the reality that technology moves on before the ink dries on the Court’s opinion (or before the Court puts electrons on the screen), Google in 2025 transferred user location history records to the users’ phones and thus says it can no longer execute geofence warrants. Other providers might have similar information, but the organization and accessibility of it will continue to evolve, thus raising questions that Chatrie cannot and does not answer.
And the final irony is that Chatrie himself may not benefit from his win. First, he has to persuade the Fourth Circuit that the geofence warrant violates his Fourth Amendment rights — that is, that the government lacked probable cause for the search, that the warrant was insufficiently particular, or that the government’s discretion under it was unreasonable. Even if he threads all of those needles, the good faith exception to the exclusionary rule may preclude suppression of evidence. Under that doctrine, officers’ reasonable reliance on a warrant makes the exclusionary rule inapplicable. For that reason, Justice Alito railed in dissent against the Court’s issuance of what he branded an advisory opinion that will do Chatrie himself no good. Perhaps so. Carpenter lost on good-faith grounds after his groundbreaking Fourth Amendment victory in the Supreme Court.
But the Supreme Court had undoubted authority and responsibility to provide guidance to the police, citizens, and lower courts about the scope of the Fourth Amendment – else many closely disputed cases would simply be dismissed on the basis of good faith without the Court ever being able to say what the law is. The Court could have done more, both for the development of the law and Chatrie. In Carpenter, for instance, the Court told the government what it had to do – “get a warrant” – and left no doubt that a properly supported and tailored warrant would satisfy the Fourth Amendment. But what the Chatrie Court did say represents a significant step in reinforcing the Fourth Amendment’s protections — and what it left open will keep commentators and courts busy for some time to come.
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* Brittanica Encyclopedia: “Jeremy Bentham’s panopticon is a design for a prison that allows for the constant surveillance of prisoners. The design features two circular towers, one inside the other, the outer one containing cells that face the inner tower from which guards, who would be invisible to prisoners, would have an unobstructed view of each cell.” To my knowledge, this is first use of “panopticon” in a majority opinion, although Justice Scalia referred to a “genetic panopticon” in his dissent in Maryland v. King, 569 U.S. 435, 482 (2013).
