The chief judge of FISC, Reggie Walton, who has reacted angrily in the past to the claims of FISC being a "rubber stamp", has now admitted that the FISC really can't check on what the NSA is doing and relies on what they tell him to make sure that they're not breaking the law.
“The FISC is forced to rely upon the accuracy of the information that is provided to the Court,” its chief, U.S. District Judge Reggie Walton, said in a written statement to The Washington Post. “The FISC does not have the capacity to investigate issues of noncompliance, and in that respect the FISC is in the same position as any other court when it comes to enforcing [government] compliance with its orders.”