The American Civil Liberties Union filed a lawsuit on Wednesday to force the FBI to reveal internal memos on GPS tracking.
The ACLU requested the documents, which provide guidance to FBI agents about using GPS devices to track suspects, last month under the Freedom of Information Act, but the FBI has yet to respond.
The lawsuit asks the court to order the FBI to produce the documents immediately.
The ACLU first learned of the existence of the memos when FBI General Counsel Andrew Weissmann mentioned them during a panel discussion at the University of San Francisco Law School in February.
He said the memos provide guidance to agents in light of the Supreme Court's decision in United States v. Jones, which held that installing a GPS device on a suspect's car qualifies as a search under the Fourth Amendment.
The first memo offers instructions on whether the decision applies to vehicles other than cars, like boats or planes. The second memo guides agents on whether the decision restricts their ability to use other location-tracking tools.
In the panel discussion, Weissmann said the FBI turned off thousands of GPS devices following the Supreme Court's decision. He explained his office had to provide guidance on how to find and retrieve the devices because it could be unconstitutional to turn them back on to locate them.
"The American public has a strong interest in the disclosure of the memoranda," the ACLU writes in its suit. "The FBI is the nation's premier law enforcement agency. How the FBI implements the Supreme Court's decision in Jones will shape not only the conduct of its own agents but also the policies, practices and procedures of other law enforcement agencies — and, consequently, the privacy rights of Americans."
Chris Allen, an FBI spokesman, said the agency does not comment on pending litigation.
—Updated at 2:54 p.m.