The D.C. Court of Appeals has ruled that warrantless use of a cell-site simulator or "stingray" violates the Fourth Amendment. The court found that Stingray devices enable "officers who possess a person's telephone number to discover that person's precise location remotely and at will." The court held that the use of a Stingray invaded a reasonable expectation of privacy and thus, was a Fourth Amendment search. EPIC recently filed a brief in a U.S. Supreme Court case arguing that warrantless location tracking violates the Fourth Amendment. EPIC has also promoted oversight of Stingrays by law enforcement agencies. An EPIC FOIA lawsuit in 2012 revealed that the FBI was using stingrays without a warrant, and that the FBI provided Stingrays to other law enforcement agencies. EPIC has also filed amicus briefs in federal and states courts arguing that cell phone location data is protected by the Fourth Amendment.