A geofence warrant is a search because it captures location data. The mere collection of private data on the phone is not intended to be shared with third parties; essentially, a cell phone user has no control over that at all. The case is remanded, however, to the Fourth Circuit to consider how the various steps of the warrant process should be applied. Chatrie v. United States, 609 U.S. —, No. 25–112 (U.S. June 29, 2026). The syllabus:
Police officers conducted a Fourth Amendment search when they acquired Chatrie’s location data from Google because an individual has a reasonable expectation of privacy in his cell-phone location information. Pp. 10–33.
(a) The Fourth Amendment protects individuals’ reasonable expectations of privacy, and governmental “intrusion into that private sphere generally qualifies as a search.” Carpenter v. United States, 585 U.S. 296, 304. The Amendment’s “basic purpose” is “to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials,” id., at 303, and it was designed “to place obstacles in the way of a too permeating police surveillance,” United States v. Di Re, 332 U.S. 581, 595. Pp. 10–29.
(1) In Carpenter, this Court held that accessing cell-site location information (CSLI) constitutes a Fourth Amendment search because “individuals have a reasonable expectation of privacy in the whole of their physical movements,” 585 U.S., at 310. The Court reasoned that CSLI provides a “detailed” and “encyclopedic” portrait of a person’s whereabouts, id., at 309, and, with that, “an intimate window into a person’s life,” id., at 311. Because people “compulsively carry” their cell phones “all the time,” the Court explained, a cell phone “tracks nearly exactly the movements of its owner,” and thus “faithfully follows” him not only through “public thoroughfares [but] into private residences, doctor’s offices, political headquarters, and other potentially revealing locales.” Ibid. The Court further observed that the “newfound tracking capacity” that CSLI gives the police “runs against everyone”—not just those “under investigation”—and “travel[s] back in time,” making possible a form of surveillance that would have been unknown prior to the digital age, id., at 311–312. Carpenter accordingly held that “[a]llowing government access to cell-site records contravenes” expectations of privacy. Id., at 311. Pp. 13–15.
(2) Everything Carpenter relied on to find that law enforcement officers conducted a Fourth Amendment search when they accessed CSLI records applies as well or better to the police’s accessing of Location History data. First, Location History provides an even more fine tuned picture of a person’s movements, pinpointing location within around twenty meters rather than within sectors of one-eighth to four square miles; it records location every two minutes or so for a daily average of 720 chartings rather than 101; and it can estimate elevation to reveal which floor of a building a phone is on. Second, Location History allows police to reconstruct “retrospective[ly],” and with no real effort, people’s comings and goings in any area, enabling “tireless and absolute surveillance” of any number of people in any number of places. Carpenter, 585 U.S., at 312. And third, Location History implicates personal privacy interests even more than CSLI, because Location History is more the cell-phone user’s own. Most cell-phone users
have no awareness of CSLI records, and would never try to retrieve them; by contrast, Google users regularly employ Location History as a personal journal. In that way, Location History resembles other private materials—e.g., emails, documents, photographs, or calendars—that even if stored on Google’s servers, a user reasonably views as his own and expects to be shielded from the “inquisitive eyes” of the government. Id., at 305. Pp. 16–18.(3) The Government’s argument that accessing only a short amount of cell-phone location information does not count as a Fourth Amendment search fails. “[E]ven short-term monitoring” can provide “a wealth of detail about [a person’s] familial, political, professional, religious, and sexual associations,” United States v. Jones, 565 U.S. 400, 415, and this Court has never understood Fourth Amendment protections as kicking in only once an intrusion “goes too far,” Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 415. Where the Fourth Amendment applies, it applies regardless of “the quality or quantity of information” the government obtains. Kyllo v. United States, 533 U.S. 27, 37. That approach makes all the more sense when, as with Location History, law enforcement officials can select the time-limited set of materials they want from an all-encompassing database. Pp. 18–23.
(4) The Government argues that the so-called third-party doctrine precludes Chatrie from invoking the Fourth Amendment’s protections. The idea is that in “authoriz[ing] Google to collect, retain, and use” his location information, Chatrie lost his legitimate expectation of privacy, and therefore his right to complain of a search. Brief for United States 15. But Carpenter refused to apply the third-party doctrine to CSLI, and no good reason exists to reach a different result for Location History. In Carpenter, the Court rejected application of the third-party doctrine to CSLI because such information is “qualitatively different” from “telephone numbers and bank records,” 585 U.S., at 309—it is incomparably “revealing” and is “not truly ‘shared’ as one normally understands the term” given that cell phones are “indispensable to participation in modern society,” id., at 315. Both differentiating features
apply equally or better to Location History, which is even more “revealing” than CSLI and is “not truly shared” in the normal sense of wanting a third party to see or use it. Id., at 315. 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. The Government’s argument that generating Location History, unlike producing CSLI, is a voluntary choice is meritless. That argument ignores how and why
Google users turn on Location History: Google repeatedly prompts users to turn on the service, often warning that devices will not “work correctly” otherwise, 2 App. 140–141, while not disclosing in that prompt how frequently users’ location information would be recorded, how precise it would be, or how it might be given to the government. More generally, an app-by-app, feature-by-feature method of granting Fourth Amendment protection misapprehends the nature of modern cell-phone use, where nearly everything requires some kind of “affirmative act” beyond “powering up” a given app or service. The Government wishes to disconnect the activities people do on their cell phones from the mere act of carrying a turned-on cell phone (the thing that
generates CSLI), with only the latter receiving assured Fourth Amendment protection. But the point of carrying smartphones is to use what is on them—as Carpenter said, to use the apps and “services they provide.” 585 U.S., at 315. Accordingly, a cell-phone user is not to be viewed as sharing private information with third parties—which then can be freely passed on to the government—just by doing the ordinary things cell-phone users do. Pp. 24–29.(b) The conclusion that a Fourth Amendment search occurred does not resolve this case, because the Fourth Amendment prohibits only searches that are “unreasonable.” When law enforcement officials undertake a search to discover evidence of a crime, the reasonableness standard generally requires that they seek a warrant from “a neutral and detached magistrate,” Johnson v. United States, 333 U.S. 10, 14, who may issue a warrant only when “probable cause is properly established and the scope of the authorized search is set out with particularity,” Kentucky v. King, 563 U.S. 452, 459. The warrant issued here, as described earlier, was an uncommon, multi-step one, and the parties have contested the legality of each stage of the search process it authorized. The Fourth Circuit did not address the questions that unusual warrant raises. Because this is “a court of review, not of first view,” Cutter v. Wilkinson, 544 U.S. 709, 718, n. 7, the Court leaves it up to the Court of Appeals to decide whether, at each step of the search process, the warrant satisfied the Fourth Amendment’s requirements of particularity and probable cause. Pp. 29–32.
