Chatrie v. United States: The Supreme Court Brings Geofence Warrants Under the Fourth Amendment

By Attorney Joe Serpa | Georgetown University Law Center | Massachusetts Criminal Defense Since 1995

On June 29, 2026, the United States Supreme Court held in Chatrie v. United States, No. 25-112, 609 U.S. ___ (2026), that police conducted a Fourth Amendment search when they acquired a suspect’s Google Location History data, because a person keeps a reasonable expectation of privacy in cell phone location information. The judgment was 6 to 3, and Justice Kagan wrote the opinion of the Court for five Justices; Justice Gorsuch supplied the sixth vote for the judgment on a separate property theory.

It is the most important digital privacy ruling since Carpenter v. United States, 585 U.S. 296 (2018), and it lands on ground Massachusetts courts prepared years ago.

The decision vacated and remanded United States v. Chatrie, 136 F.4th 100 (4th Cir. 2025) (en banc). The Court decided that the Fourth Amendment applies. It decided nothing about whether this warrant, or any geofence warrant, is valid, and Mr. Chatrie himself has not yet suppressed anything. Both halves of that sentence matter to a Massachusetts defendant, and this post covers both.

What a Geofence Warrant Is

A geofence warrant works backwards. Instead of identifying a suspect and asking where his phone was, police draw a box around a crime scene and ask a provider, usually Google, to identify every device inside the box during a window of time. The technique searches the location histories of everyone who passed through, almost all of them innocent, in the hope that one of them is the suspect. The Chatrie case began with a Virginia bank robbery and a warrant that swept the location data of every Google user near the bank for a two hour window.

What the Court Held

The majority held that people keep a reasonable expectation of privacy in their cell phone location data. A government demand for it intrudes on a constitutionally protected interest even when the window is short and the data sits with a third party. There is no short-duration pass. The Court wrote that Fourth Amendment protections do not kick in only once an intrusion goes too far. Where the Amendment applies, it applies regardless of the quality or quantity of information the government obtains.

The Court also rejected the government’s argument that users voluntarily share this data with Google, describing the exposure of the information as what happens when a user avails himself of the services on his phone. Just as the third-party doctrine did not apply in Carpenter, it does not apply to Location History. That reasoning extends Carpenter, where the Court reached the same conclusion for historical cell site location information, and it continues the retreat from the old third-party doctrine in digital cases.

What the Court Left Open

The Court remanded every question about this warrant’s validity: probable cause, particularity, and the lawfulness of the second and third steps, in which officers widened the time window and de-anonymized selected devices. All of that is now before the Fourth Circuit, which must evaluate the warrant at each step of the search process. The good-faith exception question was not part of the grant of certiorari, and the Court expressly left the Fourth Circuit free to consider it anew.

Two Justices went further. Justice Jackson, joined by Justice Sotomayor, wrote separately that she would have held this search unconstitutional, and her concurrence attacks the discretion the warrant left to officers at the second and third steps. That is a two-Justice concurrence, not the Court’s holding, and it reads as the argument the defense will make on remand rather than a rule.

So the practical state of federal law is this: acquiring Location History requires a warrant that satisfies probable cause and particularity at each step, and no one yet knows how narrow those warrants must be. In federal court, the government will argue that officers who relied on earlier law acted in good faith. The dissent read the majority as leaving the Fourth Circuit’s good-faith ruling untouched. That is where the federal fight now lives.

Massachusetts Was Already There

For Massachusetts defendants, Chatrie confirms a direction our courts chose first. The Supreme Judicial Court held in Commonwealth v. Augustine, 467 Mass. 230 (2014), S.C., 470 Mass. 837 (2015) and 472 Mass. 448 (2015), four years before Carpenter, that police generally need a warrant for historical cell site location data under Article 14 of the Massachusetts Declaration of Rights.

Commonwealth v. Estabrook, 472 Mass. 852 (2015), then set the boundary: a request for up to six hours of historical telephone-call CSLI needs no warrant, and the six hours is measured by what the Commonwealth requests, not by the slice it later offers at trial.

The rest of the framework grew case by case, and its outcomes deserve stating precisely. Commonwealth v. Almonor, 482 Mass. 35 (2019), held under art. 14 that police causing a phone to reveal its real-time location is a search, and then reversed the suppression order on exigent circumstances. Commonwealth v. McCarthy, 484 Mass. 493 (2020), adopted mosaic reasoning for automatic license plate readers, held that four fixed cameras on two bridges did not invade the defendant’s expectation of privacy, and affirmed the denial of suppression.

Commonwealth v. Mora, 485 Mass. 360 (2020), held that months of pole camera surveillance of a home is a search under art. 14 and remanded for a probable cause determination rather than ordering suppression.

The most recent word runs the other way for short windows. In Commonwealth v. Govan, SJC-13600 (Mass. June 4, 2025), the SJC held that the warrantless review of roughly twenty minutes to an hour of historical GPS data from a pretrial monitoring bracelet was not a search. Surveillance that short reveals details from isolated incidents rather than a pattern of life, and the court affirmed the denial of suppression.

A short-window geofence argument under the mosaic theory has to reckon with Govan, and the better art. 14 framing after Chatrie is the one the Supreme Court used: the acquisition of the location data itself, at any duration, is the search.

Our pages on phone, computer, and digital device searches and illegal searches and seizures explain how Article 14 routinely protects more than the federal floor. Chatrie raises that floor.

The Massachusetts Advantage: No Good-Faith Exception

No Massachusetts appellate court has yet decided a geofence warrant case. The issue is open, and it will be litigated on the framework above. That openness favors the defense here more than it would in most states, for one reason above all.

Massachusetts recognizes no good-faith exception under art. 14. Where a search warrant issues without probable cause, the evidence is excluded even if the officer relied on the warrant in objectively reasonable good faith. Commonwealth v. Fredericq, 482 Mass. 70 (2019); Commonwealth v. Upton, 394 Mass. 363 (1985).

Good faith is the doctrine that has saved geofence evidence in federal court at every stage of Chatrie itself, and it is the doctrine the Fourth Circuit may use again on remand. It has no counterpart in a Massachusetts courtroom. A geofence warrant that fails probable cause or particularity under art. 14 is not rescued by the officer’s reliance on it. For a defendant with a choice of forum arguments, that difference is the whole case.

Fredericq supplies a second tool. Evidence may be suppressed as the fruit of the poisonous tree even if it is found in a place where the defendant has no reasonable expectation of privacy. In a geofence case, where the return identifies the client and the physical evidence turns up later somewhere else, that rule is what extends the taint to the evidence found afterward.

What It Means for Massachusetts Cases

Any Massachusetts case built on a geofence return now has a suppression issue worth litigating. After Chatrie, the acquisition is a search, so a warrant is required, and the warrant must rest on probable cause and describe the search with particularity at each step. A box drawn around a busy block for an open-ended window will struggle on both fronts. The second and third steps, where officers widen the window and pick the devices to de-anonymize, are separately attackable, which is exactly why the Supreme Court directed review at each step.

Reverse keyword warrants and tower dumps raise the same everyone-to-find-someone objection, and the argument for extending Chatrie to them is strong, but no controlling authority has extended it yet. Chatrie says nothing about either technique. The leading federal appellate decision on geofence warrants themselves, United States v. Smith, 110 F.4th 817 (5th Cir. 2024), held them unconstitutional general warrants while still applying the good-faith exception; it is persuasive authority only. Counsel frames these as arguments to win, not rules to invoke.

The Commonwealth’s answers will come from three derivative-evidence doctrines, and the defense should brief them before the Commonwealth does. Independent source: evidence first found through an unlawful search is admissible if later acquired independently by lawful means, and the Commonwealth bears the burden by a preponderance of showing the absence of taint. Commonwealth v. Estabrook, 472 Mass. 852 (2015).

Inevitable discovery: Massachusetts requires proof that lawful discovery was certain as a practical matter, a demanding test measured at the time of the unlawful seizure, stricter than the federal rule. Commonwealth v. O’Connor, 406 Mass. 112 (1989); Commonwealth v. Balicki, 436 Mass. 1 (2002).

Attenuation: three factors, elapsed time, intervening circumstances, and the purpose and flagrancy of the misconduct, and consent obtained by confronting the client with the tainted return does not attenuate anything. Commonwealth v. Fredericq, 482 Mass. 70 (2019).

Discovery should track the steps rather than asking generally for the warrant package. Counsel demands the complete affidavit and every attachment, the coordinates, radius, and time window, and what the magistrate was told about how many uninvolved people the box would sweep in. Counsel demands the warrant’s own terms for the second and third steps and whether any judge reviewed the narrowing, or whether officers applied their own criteria, which is the discretion the Jackson concurrence attacked.

Counsel demands Google’s native productions at each step with device counts, the de-anonymization request, every investigative step between the anonymized return and the client’s name, and every later warrant whose probable cause rests on the return. Preservation letters go out immediately, before the provider purges the underlying data.

The framework is laid out in our post on digital search warrants in Massachusetts and in the digital search FAQs. Location data questions in car cases are covered in our guide to the modern Massachusetts traffic stop.

Timing of the Fourth Amendment Ruling

Chatrie is best understood as the fourth step in a line the Court has been walking for fifteen years. United States v. Jones, 565 U.S. 400 (2012), held that attaching a GPS tracker to a car is a search. Riley v. California, 573 U.S. 373 (2014), required a warrant to search a phone seized at arrest and recognized that digital devices hold the privacies of life.

Carpenter, 585 U.S. 296 (2018), then refused to let the government use the old third-party doctrine of Smith v. Maryland, 442 U.S. 735 (1979), and United States v. Miller, 425 U.S. 435 (1976), to obtain week-long location histories without a warrant. Chatrie completes the thought. If the government cannot demand your location history by name without a warrant, it cannot avoid the problem by demanding everyone’s location history by place.

A new Fourth Amendment rule applies to cases still pending on direct review where the issue has been preserved. Griffith v. Kentucky, 479 U.S. 314 (1987). Massachusetts states the same rule for its own new search rules, with the same preservation condition. Commonwealth v. Augustine, 467 Mass. 230 (2014). So counsel raises Chatrie now, in writing, in every pending case that involves a geofence return, a tower dump, or a reverse keyword demand.

Retroactive application of the search holding is not the same thing as suppression: in federal court the good-faith exception still stands between the client and exclusion, which is one more reason the art. 14 route matters.

Massachusetts already requires a warrant when police cause a phone to reveal its real-time location, Commonwealth v. Almonor, 482 Mass. 35 (2019), and the combination of Chatrie and Article 14 gives Massachusetts defendants two independent bodies of law to litigate under.

Who Geofence Cases Sweep In

Geofence returns do not select for guilt. They select for proximity, and in Boston and Cambridge proximity means students and young professionals. A box drawn around a late-night incident near a campus, a stadium, or a nightlife block sweeps in every phone in the crowd, and the person contacted weeks later is often a college or university student with no idea why police are calling. The right response is silence and a lawyer, as our guides on the right to remain silent and the first 24 hours after an arrest explain.

For a licensed professional or anyone whose career depends on background checks, the arraignment itself is the injury, which makes the suppression fight and the pre-arraignment posture of these cases worth everything. Where the case begins with a complaint application instead of an arrest, the clerk-magistrate hearing is the place to attack a thin geofence identification before any record exists.

Serpa Law Office litigates digital search issues across Massachusetts. If your case involves location data, a device search, or any warrant you have not seen, contact Serpa Law Office at 617.936.0201 for a confidential consultation.