Find one pagers, infographics, cases, and many more resources on Cell Site Location Information

EFF Briefs

EFF Amicus Briefs

  • Carpenter v. U.S., 585 U.S. ___, 138 S. Ct. 2206 (2018) in the Supreme Court of the United States, our amicus briefs both encouraged the Court to take the case and argued that police must get a warrant before collecting the detailed location data that all phones generate as part of their routine functioning.
  • U.S. v. Elmore (Gilton), et al., in the U.S. Court of Appeals for the Ninth Circuit, our amicus brief argued that police need a search warrant to obtain historical cell site records from a cell phone provider.
  • Commonwealth v. Augustine, 467 Mass. 230, 4 N.E. 3d 846 (2014)  in the Commonwealth of Massachusetts Supreme Judicial Court, our amicus brief urged the Court to rule that police must get a search warrant in order to access historical cell site information.
  • State of Maine v. O’Donnell, pending before the Maine Supreme Court, is a case where police asked Verizon to provide real-time CSLI on the phones of two burglary suspects. The carrier “pinged” the phones and transmitted the locations to police, who arrested the pair. Our amicus brief argued that while the Carpenter decision involved historical cell phone location data, the rule articulated by the U.S. Supreme Court—that collection of historical CSLI from third party phone companies is a Fourth Amendment search that requires a warrant—applies equally to real-time CSLI collection.
  • Commonwealth of Massachusetts v. Almonor, pending before the Massachusetts Supreme Court, involves a similar case where police had a phone carrier "ping" the cell phone of a suspect in a murder case. The real-time CSLI search pinpointed the suspect in a private home. The state contends it can warrantlessly get cell phone location data to locate anyone, anytime, at any place for up to six hours. A trial court disagreed and the state appealed. Our amicus brief likewise argued that the Carpenter decision should apply to searches of real-time CSLI.

EFF Blogs and Press Releases

Academic Articles and Research

Legislation

Law Enforcement Training Guides and Materials