A New York Times editorial reports that a Philly appeals court will hear arguments today in a precedent-setting case to decide if government officials need a warrant to track your cell phone. "The United States Court of Appeals for the Third Circuit, in Philadelphia, could be the first federal appeals court to rule on what legal standard should apply to government requests for locational information. Because of the particular facts of this appeal, the court may do so on narrow statutory grounds. But, in this case or another one, the courts should make clear that the Fourth Amendment requires the government to obtain a search warrant for locational records after showing probable cause for connecting the phone user to criminal activity. Information about a person’s movements is by nature extremely private. It can reveal where they attend religious services and what political meetings or protests they are involved in. It can provide evidence of marital infidelity. If the courts allow the government to obtain these records without probable cause, the impact on ordinary people’s freedom will be substantial."