Supreme Court 6-3 Ruling Kills Geofence Warrants for Location History(最高裁の6-3判決は、場所の歴史のためのジオファンス命令を殺す)

6-3 Supreme Court ruling on Monday extinguishes the government's favorite dragnet surveillance tool: geofence warrants. The majority held that the Fourth Amendment protects a user's "location history" collected by third parties like Google, requiring a warrant based on probable cause before turning that data into a surveillance pipeline.

What the Court Actually Ruled

The logic isn't new. Courts already require a warrant for cell-site location information from carriers. Monday's decision simply extends that same protection to Google's Location History and any equivalent service. Writing for the majority, the justices found "no good reason exists to reach a different result" when the data flows through a third-party platform rather than a carrier's tower logs.

That's a direct hit on geofence warrants — the practice where police draw a digital box around a crime scene and demand Google hand over every device that passed through it, sometimes sweeping up hundreds of innocent bystanders. No more fishing expeditions. The government must now show reasonable cause that a specific phone was involved.

Why This Hits Google Hardest

Google's Sensorvault database, which stores years of Location History from Android and Google Maps users, has been the primary target of geofence warrants. The company reportedly received over 11,000 such requests in 2020 alone, many of them broad dragnets. Monday's ruling forces law enforcement to narrow those asks to specific accounts with probable cause — a far higher bar.

The 6-3 split signals that even a conservative-leaning Court sees third-party data collection as an extension of physical surveillance. Chief Justice Roberts and Justice Kavanaugh joined the liberal bloc, while Justices Thomas, Gorsuch, and Alito dissented. No ambiguity for lower courts.

Expect an immediate drop in geofence warrant filings, and a surge in motions to suppress evidence already gathered under the old regime. Every company collecting granular location data — from Uber to Apple's Find My network — just got legal cover to push back on overbroad requests.

Source: Supreme Court ruling guts government's use of geofence warrants
Domain: arstechnica.com