The Supreme Court today heard a case regarding whether or not law enforcement can access certain types of cell location data without a warrant. Government agencies do not currently need a warrant when requesting location and other data held by phone companies thanks to a 1979 court case. In that case, the Supreme Court decided a suspect had no reasonable expectation of privacy because he dialed phone numbers into his home phone. In so doing, he gave the phone company, a third party, that information. Personal data held by third parties is not as protected as information held by suspects. This third-party doctrine is what allows law enforcement to seek suspects' historical movements from cell phone companies without obtaining a warrant. In more recent cases, the Supreme Court has ruled that the government needs a warrant to seek GPS data and search suspects' cell phones. Today's case, Carpenter v. United States, argues that the third-party doctrine is outdated and that law enforcement seeking such data should be required to obtain a warrant as it would for GPS data. Carpenter's lawyers argued taking location data from a third party without a warrant violates the Fourth Amendment. "Most Americans, I think, still want to avoid Big Brother," noted Justice Sonia Sotomayor, further saying most people take their phones into bathrooms, bedrooms, and dressing rooms, all places where they expect privacy. At least four justices agree with Carpenter's basic argument, according to the Associated Press. The panel of justices will make a decision on the matter by next June.