The leader of the secret court that is supposed to provide critical oversight of the U.S. government's vast spying programs says its ability do so is limited and that it must trust the government to report when it improperly spies on Americans.

The chief judge of the Foreign Intelligence Surveillance Court says it lacks the tools to independently verify how often the federal government's surveillance breaks the court's rules that aim to protect Americans' privacy. Without taking drastic steps, it also cannot check the veracity of the government's assertions that the violations its staff members report are unintentional mistakes.

"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 compliance with its orders."