Court Cases

The Line of Cases

From GPS Trackers to Location History

United States v. Jones, 565 U.S. 400 (2012)

The Court held that attaching a GPS tracker to a vehicle was a Fourth Amendment search, on trespass grounds. Separately, five justices in concurrence reasoned that long-term GPS monitoring impinges on reasonable expectations of privacy - the seed of the aggregation principle.

Opinion (Justia)

Riley v. California, 573 U.S. 373 (2014)

A unanimous Court held that police generally need a warrant to search a cellphone seized incident to arrest. The reasoning rests on the vast scope of digital data: a phone is not a wallet, and digital information receives strong Fourth Amendment protection.

Opinion (Justia)

Carpenter v. United States, 585 U.S. 296 (2018)

The Court held that government acquisition of historical cell-site location information - records revealing a person's movements over time - is a Fourth Amendment search, generally requiring a warrant. Decided June 22, 2018.

Official print (supremecourt.gov, PDF)

Chatrie v. United States, No. 25-112 (2026)

Decided June 29, 2026 (6-3). The Court held that police acquisition of a person's stored Google Location History through a geofence warrant is a Fourth Amendment search - individuals have a reasonable expectation of privacy in stored cellphone location information.

The caveat we always carry: the Court did not decide whether the geofence warrant used in the case was valid. It remanded for the lower courts to assess probable cause and scope. Geofence warrants were not struck down; the acquisition of this data was held to require Fourth Amendment scrutiny.

Slip opinion (supremecourt.gov, PDF)

What these cases mean for ALPRs: none of them decides every ALPR program, and we never claim otherwise. Together they establish that aggregated location surveillance raises grave Fourth Amendment concerns and demands strict constitutional scrutiny. How courts apply that principle to networked plate readers is being litigated now - which is exactly why we watch.

What We Watch

The Open Questions

• Schmidt v. City of Norfolk (4th Cir. No. 26-1227) - the direct Fourth Amendment challenge to a citywide Flock network (roughly 172-176 cameras; plaintiffs' cars logged 526 and 849 times in about four months). On Jan 27, 2026 the district court upheld the network - it does not violate the Fourth Amendment "yet" - and the appeal is pending as of Aug 2026 (WHRO; Courthouse News). We say it plainly: no court has ruled Flock unconstitutional in Norfolk.
• Virginia's state-court pair - a Norfolk Circuit Court judge suppressed warrantless Flock evidence, likening the network to GPS tracking; the Virginia Court of Appeals reversed in an unpublished opinion, holding plates in public view carry no reasonable expectation of privacy (GovTech; 13NewsNow).
• The Chatrie remand - how the lower courts assess the probable cause and scope of the geofence warrant on remand.
• Public-records angle - Skagit County (WA) Superior Court ruled Nov 6, 2025 that Flock images and data are public records subject to disclosure, prompting several Washington deactivations (GeekWire).
• Oklahoma - State v. Ifabiyi (McClain County District Court, 2024) suppressed ALPR evidence under 47 O.S. § 7-606.1; a trial-court ruling, not binding statewide precedent. Detail on the Oklahoma page.
• State constitutional privacy decisions - state supreme courts interpreting their own constitutions' privacy protections, which can exceed the federal floor.

Developments are added here after verification, and logged on Sources & Corrections.