A detailed look at how police forces use “geofence” warrants and Google's Sensorvault location history database to find witnesses and suspects near crime scenes
The tech giant records people's locations worldwide. Now, investigators are using it to find suspects and witnesses near crimes …
Context & Ripple Effects
This NYT explainer landed two months after Slate first documented police reverse location search warrants sweeping up everyone near a crime scene, and it names the machinery behind the practice: Google's Sensorvault, a worldwide location-history database that turns any address into a suspect pool. It became the reference point for everything that followed.
The arc since runs through mounting legal challenges to geofence warrants, Google's first disclosure of warrant volumes — 8.3K in 2019 rising to 11K in 2020, an expansion into nonviolent cases, and finally Google's decision in late 2023 to stop responding after changing how Maps stores location data.
First-order effects
- Police forces gain a template for casting a digital dragnet: query Sensorvault by radius and time, then narrow from anonymized devices to named suspects — with everyone else near the scene swept in as potential witnesses.
- Google is cast as gatekeeper of criminal investigations, forced to build review processes for warrants its ad-driven location collection never anticipated.
Second-order effects
- Courts become the battleground: defense attorneys and judges must decide whether dragnet queries pass constitutional muster, and the resulting case law shapes how far any company can be compelled to hand over bystander data.
- Rival platforms and app makers face pressure over their own location retention, since any comparable history database makes them the next subpoena target.
Third-order effects
- If the pattern holds, mass location retention becomes a liability rather than an asset: platforms restructure how they store history precisely to shrink their warrant exposure, trading product capability for legal insulation.
- Location privacy hardens into a structural fault line between law enforcement's investigative appetite and consumer data practices, settled case-by-case rather than by statute.
The trend: Consumer location databases are turning tech companies into involuntary intermediaries of criminal investigation — until the companies redesign their data storage to shut the spigot.