police need – In a 6-3 decision, the Supreme Court ruled that police generally need a warrant to search smartphone location data, tightening Fourth Amendment limits on digital surveillance. The ruling in Chatrie v. United States also rejected a key “third-party doctrine” ar
Monday’s Supreme Court decision landed like a brake on a machine that’s been accelerating for years: without a warrant, police can’t rummage through the digital record of where your phone has been.
In Chatrie v. United States, the Court ruled 6-3 that smartphone location data is subject to privacy protections under the Fourth Amendment. The conservative justices John Roberts. Brett Kavanaugh. and Neil Gorsuch joined the liberal bloc—Sonia Sotomayor. Elena Kagan. and Ketanji Brown Jackson—in reaching that conclusion.
The case. described in the ruling as a first major step on digital surveillance since 2018. also sits amid a week of attention-grabbing decisions. including one that blocked President Donald Trump’s 2025 executive order attempting to overturn the guarantee of birthright citizenship. Still, Chatrie’s impact is likely to outlast the news cycle.
It’s the Court’s biggest privacy ruling in about a decade. according to the source material. and it follows a line drawn in Carpenter v. United States. In 2018, the Court held that law enforcement’s warrantless search of cell site location history violated the Fourth Amendment. Now. Chatrie asks whether similar protections apply when the government reaches not just at cell towers—but into the location data ecosystem built around smartphones.
At the center of Chatrie is law enforcement’s use of a “geofence warrant” in 2019 to identify a potential suspect in a bank robbery. Geofence warrants—sometimes called “reverse warrants”—work differently from traditional search warrants.
In the classic warrant model. police must show particularized suspicion about a person or place. and a neutral decision maker—like a judge or magistrate—approves the search based on that justification. With a geofence warrant, police start with a location instead of a suspect. They draw a boundary around an area and then ask a company. in this case Google. for all devices found within that location during the relevant time.
The 2019 warrant covered more than a bank. A church sat nearby, and there might have been people’s homes or other businesses inside the line. The source material emphasizes the scope: the geofence process was not limited to a single target.
There’s another reason the method matters. The interview frames the technique as newly enabled by modern technology. In the account provided. the technology at issue is described as the sort of surveillance and investigation that the founders “could not have imagined” when debating the Fourth Amendment. The practical point is that the police can retroactively follow and compile people’s movements through private spaces and homes at a level of granularity that wasn’t available before.
The Supreme Court also confronted a detailed three-step process tied to what the warrant authorized—and that sequence is where the decision’s stakes feel most personal.
Once the judge approved the warrant. the process allowed Google and police to proceed without returning to the magistrate at each stage. First, Google looked within the drawn boundary and returned anonymized information about all devices in that location. In this case, the initial step returned 19 devices. Police then narrowed their attention: they decided they wanted information about nine.
The source material is blunt about the implication. At each step, the police were receiving data from people who, by the logic of the search, were affirmatively not the suspect. And because the search began with a location, it could sweep in anyone who happened to be in the area.
Second, police asked Google for more information about the nine accounts. The identities were still not revealed at that point. but the police could now see two hours of granular location information about where those devices went before and after the crime. Google captures location data once every two minutes. and the account also says the system can capture elevation data—enabling distinctions like being on the third floor rather than the tenth floor.
Third, the warrant directed police to review the more granular information and determine which devices to unmask. That step would reveal identities—again, in the source’s telling, including accounts beyond the person ultimately prosecuted. Here, police de-anonymized three accounts, including people who were affirmatively not the suspect.
What did the Court say about that process?. The decision was not unanimous. Six justices aligned behind the view that the lower court’s judgment should be vacated—meaning the case required closer review because a search under the Fourth Amendment had occurred. Five justices signed onto the main opinion written by Justice Elena Kagan.
Justice Neil Gorsuch wrote a separate opinion that reached the same destination through a different route.
Kagan’s opinion, as described in the interview, takes up Carpenter as the guiding precedent. Carpenter concerned cell site location information. and Kagan’s decision treated the government’s request to Google for the location data in this case as a search. That matters because once the request is treated as a search, Fourth Amendment scrutiny follows. The source material says the opinion left open for another day whether the warrant itself was appropriate. but it ruled that—at least for Fourth Amendment purposes—the government had conducted a search.
One of the most consequential parts of the ruling is what it says about the “third-party doctrine.” In the interview’s framing. that doctrine is an exception to the Fourth Amendment: once a person voluntarily shares information with a third party. like Google. the person loses reasonable expectations of privacy and the Fourth Amendment does not apply.
Kagan’s opinion rejected that argument here. Using a cell phone in the way cell phone users do, the opinion says, does not mean people give up their rights to private information just because a corporate entity is involved.
That is why the decision landed as something more than a technical victory over a narrow warrant. The source material points to Justice Samuel Alito’s dissent as a counterpoint: Alito is described as arguing that the Court’s reasoning could reach broader digital surveillance.
In the interview. Stevie Glaberson—director of research and advocacy at Georgetown Law’s Center on Privacy and Technology—treats Alito’s warning as both a warning and a sign of the direction of travel. The interview also notes that the Center filed an amicus brief alongside the Electronic Frontier Foundation and the ACLU.
Glaberson’s core concern is the structure of modern data collection. If corporate tools can mediate everyday life—communications with families. managing finances. and even personal thoughts—then extending the third-party doctrine to cover that mediation would swallow the Fourth Amendment’s rule. In that account. the Court’s refusal to do so keeps the Fourth Amendment meaningful in a digital economy built on intermediaries.
The everyday consequences are framed in concrete terms. The interview describes a world where geofence reverse location searches and facial recognition technology can affect people broadly. not just those suspected of crimes. The worry is that law enforcement and companies don’t always distinguish between targeted interest and everyone else. including when they “vacuum up information” through data brokers or scan crowds with facial recognition. The research cited in the source material says that. as of 2021. the majority of American adults were in Department of Homeland Security immigration databases and could be located by ICE and CBP.
Those capabilities are presented not as abstract concerns, but as practical threats to how communities organize. Because information about one person can become information about a group. the account warns police could surveil and track people from afar. without their knowledge. and identify when they go to protests or gather.
In that light, Glaberson’s closing plea is directed at the rules themselves: placing limits on police and government is described as vital for community action and for democracy.
For now. Chatrie does not solve every question about how warrants must be written or what exactly makes a geofence search lawful in every case. But Monday’s decision draws a clear line: smartphone location data cannot be treated as automatically available to police on demand. It has Fourth Amendment protections.
And that, for the millions carrying location-tracking devices all day long, is the central shift. The court’s ruling signals that the digital trail left behind by ordinary life remains legally guarded—even when the government starts with a map instead of a suspect.
SCOTUS Chatrie v. United States smartphone location data Fourth Amendment geofence warrant Google digital privacy third-party doctrine Carpenter law enforcement warrants ICE CBP ICE and CBP Donald Trump 2025 executive order