Police across the US are increasingly using “reverse location search warrants” to force tech companies to hand over location data of anyone near a crime scene
Context & Ripple Effects
Slate's report lands a year after the Supreme Court held that police need a warrant to obtain mobile-phone tower location records — a decision that pushed investigators toward a different mechanism: rather than tracking one suspect over time, they now demand the locations of everyone near a scene at a moment. The related coverage shows this technique scaling fast around Google's Sensorvault database, with the geofence warrant practice becoming standard investigative procedure within months.
What follows is a widening arc: by 2020 the tactic draws courtroom challenges in California and Virginia, and by 2023 a review of 115 warrants shows its use spreading well beyond violent crime. Meanwhile, some local agencies skip the warrant question entirely with tools like Fog Reveal, which searches device records without judicial sign-off.
First-order effects
- Google becomes the default custodian of crime-scene location data, forced to hand over records of every user near an incident — including people with no connection to the case.
- Bystanders swept into these searches have no notice and no individualized basis for the seizure of their location history.
Second-order effects
- Courts in California and Virginia begin scrutinizing whether blanket geofence requests satisfy Fourth Amendment standards, forcing judges to define limits the Supreme Court never set for this technique.
- As companies face legal and reputational friction over handing over bulk data, some agencies route around them entirely — turning to broker tools like Fog Reveal that operate at times without warrants.
Third-order effects
- If the pattern holds, US policing splits into two tracks: judicially reviewed geofence demands on major platforms, and warrantless commercial data brokers filling the gap — shifting the constitutional fight from phone companies to an unregulated data-broker market.
- The Supreme Court's warrant requirement for historical location records gets tested against techniques that invert the logic: instead of tracking a known suspect, police identify suspects by first seizing everyone's data.
The trend: Location-based policing is expanding from targeted tracking of individuals to dragnet searches of everyone near a scene, with data brokers emerging as the workaround as courts and platforms push back.