In the wake of the Supreme Court's decision earlier this year striking down the use of a GPS tracker on a suspect's car without a warrant, the FBI issued two memos to agents with new guidelines for the use of the surveillance technology.

But the agency is withholding those memos from the public and has failed to respond to a records request submitted by the American Civil Liberties Union in July to obtain the documents.

On Tuesday, the ACLU filed a lawsuit against the FBI (.pdf), seeking the immediate release of the documents on the grounds that the public has a strong interest in knowing how the FBI is complying with the ruling.