Chatrie v. United States · ¶10

In recent years, law enforcement officers have employed so-called geofence warrants to obtain information that technology companies collect about their users’ cell-phone locations. Suppose that investigators know a crime was committed at a particular place and time, but do not have a suspect. They may draw a “geofence”—a virtual perimeter—around the crime scene and get a warrant compelling a company to hand over data about the cell phones located in that area near the time of the crime. Following a process specified in the warrant, the company will turn over the cell-phone data and eventually identify by name one or more of the users thus disclosed.

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