EFF joined the American Civil Liberties Union (ACLU) Foundation and the ACLU Foundation of Texas in backing a judge who required a search warrant before approving the seizure of two months of cell phone location data by law enforcement.  In this case, the government asked a magistrate judge to approve a request to two cell phone companies for 60 days of cell phone location records as part of a routine law enforcement investigation. The judge denied the request, saying it was necessary for the government to get a warrant based on probable cause before it could obtain the records. In an amicus brief filed in the U.S. Court of Appeals for the Fifth Circuit, EFF argues that the judge was correct, as getting a warrant is essential to ensuring Fourth Amendment protections.

The case was argued to the Fifth Circuit in October 2, 2012 in New Orleans. In July 2013, the Fifth Circuit reversed the lower court in a 2-1 decision, ruling that law enforcement didn't need a search warrant to access historical cell site records.