This Sunday, the New York Times reported on a recent trend–prosecutors’ growing use of a defendant’s Global Positioning System device (e.g., cell phone, car, among others) to prove the defendant’s location. For instance, prosecutors in suburban Chicago used data from a defendant’s GPS device in his car to place the defendant at the scene of a murder. To be sure, tracking a person’s location is common-place in criminal investigations. But my colleague Renée Hutchins (who is quoted in the NY Times article) cautions that law enforcement should be allowed to acquire GPS data only by getting a warrant. In her recent UCLA Law Review article entitled Tied Up in Knotts? GPS Technology and the Fourth Amendment, Hutchins develops that argument.