WaPo: The Volokh Conspiracy: Applying the Fourth Amendment to placing calls from a locked phone to identify its owner by Orin Kerr:
A story in the Sacramento Bee flags a novel Fourth Amendment issue pending in federal court. Here’s the issue: If the police find a locked phone that was left behind at a crime scene, do the police need to get a warrant before trying to identify the phone’s owner by calling 911, thereby generating a caller-ID record at 911 that discloses the phone’s number and leads to identification of its owner?
This question has come up in the “Gone Girl” kidnapping case currently before Judge Troy Nunley in Sacramento. As I understand the facts from the SacBee story, the defendant, Matthew Muller, allegedly attempted a home burglary months after the kidnapping. The homeowner fought back, and Muller fled. In the course of fleeing, Muller left his locked cellphone behind.