By John Ellis[1]

Editor’s Note: This article is a companion to our earlier primer on Chatrie v. United States, which explained the Supreme Court’s June 29, 2026, holding that obtaining a person’s Google Location History through a geofence warrant is a Fourth Amendment search. See The Fourth Amendment Catches Up to Digital Dragnets.

Here we turn from Google to the wireless carriers. Our thesis is simple: because Chatrie forecloses the government’s no-search and third-party defenses to carrier location data, the real fight over cellular area searches now moves to the warrant itself—its probable cause, particularity, and execution, and whether good faith can save a defective one. Google has started storing Location History on users’ phones instead of its own servers, which makes the classic Google geofence warrant harder to run. The technique law enforcement is turning to instead is the cellular area search, in which a search warrant requires a wireless carrier to determine which devices were within a specific geographic area during a certain time-period. This piece explains what those searches are, how their Timing Advance and proprietary location-estimate data compare to the records in Carpenter and Chatrie, and why Chatrie‘s reasoning reaches them with at least equal force. Because these searches already proceed by warrant, Chatrie‘s significance is not that it requires one; it is that it puts the warrant’s probable cause, particularity, and execution squarely in play. Defenders and CJA practitioners handling carrier location evidence should read this alongside the Chatrie primer and assess the implications now.