The Obama administration is again arguing that a lawsuit accusing the National Security Agency of vacuuming up Americans’ electronic communications without warrants threatens national security and would expose state secrets if litigated.

“This case may be dismissed on the ground that its very subject matter constitutes a state secret,” the government said in a legal filing in San Francisco federal court.

Brought by the Electronic Frontier Foundation, the case is now four years old and its merits have never been litigated. The civil rights group claims that the major telecoms provided the NSA a warrantless backdoor to the nation’s communication backbone.