Chatrie and the Future of Digital Privacy

On June 29, 2026, the Supreme Court decided Chatrie v. United States, which held that the government conducts a Fourth Amendment search when it obtains a person’s cellphone location data from a third party using a “geofence warrant.” As the world becomes increasingly digital, the questions of whether and how the Fourth Amendment applies to data become increasingly important — Chatrie begins to provide answers.

What Is a Geofence Warrant?

A geofence warrant is an investigative tool used by law enforcement to identify cell phones and their movements within a defined geographic area over a specified time. Unlike a traditional warrant, in which police first identify a suspect and then seek court approval to search for evidence, a geofence warrant reverses that process.  Instead of starting with a known suspect or discrete location (a house, office, etc.), police identify an area to search by defining a virtual perimeter or “geofence.” Police then obtain a warrant compelling a technology company to disclose cellphone data from within the geofenced area during the relevant time frame.

Facts

Chatrie concerned one such warrant. On May 20, 2019, a man robbed a Virginia credit union, having made off with nearly $200,000 in cash.  In the minutes leading up to the robbery, he was seen talking on a cell phone nearby.  With the robber still at large and knowing that he had recently used a cell phone, police applied for a geofence warrant. The warrant commanded Google to turn over “location history data,” revealing “a time-stamped record of every place” the cell phones near the bank around the time of the robbery had been. 

The warrant application outlined a three-step process for Google and police to follow, which was designed to narrow down the universe of potential suspects based on anonymized data. At step one, Google produced to the government “anonymized location data” for all cell phones contained in the geofence for 30 minutes before and 30 minutes after the robbery. At step two, the government ruled out certain devices by comparing time-stamped location data for each device against “known time and location information” that was specific to the robbery.  Google then provided the government with additional anonymized data — cell locations inside and outside the geofence during a two-hour window. Finally, at step three, the police narrowed the list even further by further comparing the additional information against crime-specific information.  Following this process, Google turned over identifying information for three users.  One of these users, Okello Chatrie, was ultimately charged with robbing the credit union. 

The Decision

At issue in Chatrie was whether the government violated the Fourth Amendment, a question that requires a two-step analysis. 

First, the Court had to determine whether law enforcement conducted a Fourth Amendment “search” when it obtained the cellphone data that led to Chatrie’s arrest. If the acquisition of that data did not constitute a search, then it was invisible to the Fourth Amendment.  But if obtaining the location-history data did constitute a search, then its constitutional muster depended on whether the search was reasonable — that is, whether it was supported by a valid warrant (or exception to the warrant requirement).

Justice Kagan, writing for the Court, answered the first question in the affirmative:

police conducted a search when they gained access to Location History data. An 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. Chatrie v. United States, No. 25-112, slip op. at 2 (U.S. June 29, 2026).

But the Court declined to resolve the second inquiry. Instead, it remanded the case to the Court of Appeals to determine whether the search was reasonable in light of the warrant issued — specifically, whether “each of its steps was properly described with particularity and found to be supported by probable cause.”  Id.

The Future

In some respects, Chatrie is unremarkable. The Court’s holding seems to be a straightforward application of Carpenter v. United States (holding that individuals have a reasonable expectation of privacy in “the whole of [their] physical movements” revealed by more than one week’s worth of cell site location information).  585 U.S. 296, 310 (2018).  As Justice Kagan put it: “Everything Carpenter relied on . . . applies as well or better to the police’s accessing of Google’s Location History data.” Chatrie, slip op. at 16.

Chatrie is interesting, however, because it is the Court’s most recent attempt to lay the metes and bounds of the Fourth Amendment in the digital age — it may serve to uproot current Fourth Amendment doctrine and shape the future of the same.

Chatrie may spell the practical end of the “mosaic theory” of the Fourth Amendment. The mosaic theory calls for courts to evaluate the cumulative effect of data collection by law enforcement in determining whether the Fourth Amendment’s “reasonable expectation of privacy” is implicated. Just as one tile in a mosaic reveals little yet a clear picture emerges when viewing all tiles at once, one piece of data may reveal little about a person yet multiple (otherwise innocuous) datapoints may reveal substantial private information about a person. The theory has proven difficult in practice, with courts struggling to strike the proper balance — is two days’ worth of data too much? Does it matter if the data is taken from a license plate reader, as opposed to a pole camera?  Chatrie ruled that obtaining two hours of location data was a search, and so the ceiling is low.

Chatrie also left open the question of whether (and how) the “third party doctrine” applies to digital information. The Court analogized location history to “emails, documents, photographs, [and] calendars” that individuals “reasonably view [ ] as [their] own,” notwithstanding the fact that this information is stored on a third party’s private server.  Id. at 18.  Justice Alito, in dissent, asked the obvious question that follows: “where does the boundary between Carpenter and the third-party doctrine lie after today?” Id. at 20 (Alito, J., dissenting). According to Justice Alito, “a person’s Google search history or Venmo transaction log . . . fall squarely within the third-party doctrine,” and although Chatrie — limited to “cell phone location information” — does not “ostensibly disturb that fact,” it is difficult to see why, considering that such data can paint a “similarly detailed picture about a person’s private life.” Id. After Chatrie, it is unclear whether the third-party doctrine remains frozen in time, and if not, how and why does it apply to digital information other than cell phone location information.

Chatrie thus answered some questions and invited more.