…is the subject of a pending cert. petition to the Supreme Court, reports Ars Technica (here). The issue is whether law enforcement's use of cell phone data to locate a person is subject to the privacy protections of the Fourth Amendment (such as the warrant requirement). The en banc Eleventh Circuit answered no (here). The petition's chances got a boost this week when the Fourth Circuit took the opposite view, rejecting a "shrunken Fourth Amendment" and holding that law enforcement's use of cell location data requires a warrant (here).
At the heart of the debate is whether the third-party doctrine, under which a person has no reasonable expectation of privacy in information voluntarily disclosed to the third party, applies to cell phone information. The third-party doctrine was developed in the 1970s in a very different technological landscape. Today everyone with a cell phone unavoidably shares information about themselves, including location information, with their providers. If the third-party doctrine applies, none of this information is protected by the Fourth Amendment. Will the same Supreme Court that unanimously rejected the constitutionality of round-the-clock GPS surveillance in U.S. v. Jones and unanimously required a warrant to search the contents of a cellphone in Riley v. California extend the third-party doctrine to today's technology? It seems unlikely.