Chatrie v. United States · ¶22

As those demands began to proliferate, Google worked with law enforcement officials to develop a three-step protocol to govern geofence warrants. At the first step, Google produces anonymized (i.e., no names attached) location data for all cell phones (or other devices) within the geofence—typically, a circle with a designated radius surrounding a latitude/longitude coordinate—during a specified timeframe. That data generally includes each phone’s latitude/longitude coordinate and corresponding timestamp; an estimate of that information’s accuracy; and a description of the information’s source (e.g., a Wi-Fi network, a cell site, or some other). The data at this stage shows each user’s location, every two minutes or so, within the geofence. At the second step of the process, officials review the data produced and typically ask Google to provide additional information for a subset of…

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