The Fourth Amendment finally caught up to the smartphone era. On Sunday, the Supreme Court ruled that geofence warrants—the controversial technique allowing law enforcement to demand location data on every device within a geographic area during a specified time—constitute unreasonable searches under the Constitution.

The decision represents the most significant expansion of digital privacy rights since Carpenter v. United States in 2018, when the Court held that accessing historical cell-site location data requires a warrant. This time, the justices went further: even with a warrant, the government cannot conduct the digital equivalent of stopping and frisking everyone who happened to walk past a crime scene.

What geofence warrants actually do

The technique emerged around 2016, when law enforcement agencies discovered they could serve Google with warrants demanding anonymized location data for every device that pinged within a defined geographic boundary during a specific window. Investigators would then narrow the pool, request identifying information on suspicious devices, and build cases from there.

The problem, as privacy advocates argued for years, was the inversion of traditional investigative logic. Instead of identifying a suspect and seeking evidence, police were vacuuming up data on thousands of innocent people to find a suspect. A geofence warrant served on a protest, a church, or a medical clinic could expose constitutionally protected activity.

Google reported receiving over 60,000 geofence requests from U.S. law enforcement between 2018 and 2023 before it began phasing out the practice. Other tech companies received similar demands.

The Court's reasoning

Writing for the majority, the justices held that the "particularity" requirement of the Fourth Amendment—which demands warrants describe the specific place to be searched and persons or things to be seized—cannot be satisfied by geofence requests. Drawing everyone within a radius into a criminal investigation, the Court found, is constitutionally indistinguishable from the "general warrants" the Founders explicitly rejected.

The ruling does not eliminate all location-based investigative techniques. Police may still obtain warrants for specific individuals' location histories, subpoena records from specific accounts, or use other targeted methods. What they cannot do is treat geography as probable cause.

Our take

This is the rare privacy ruling that actually matters. Geofence warrants represented a genuinely novel threat—not because the government wanted to track criminals, but because the technique made everyone a potential suspect by default. The Court recognized that constitutional protections must evolve with technology, not lag a decade behind it. For once, the Fourth Amendment arrived before the damage became irreversible.