You ever heard of National Security Letters?

NSLs typically contain a nondisclosure requirement forbidding the recipient of an NSL from disclosing the FBI had requested the information.[2] The nondisclosure provision must be authorized by the Director of the FBI, and only after he or she certifies “that otherwise there may result a danger to the national security of the United States; interference with a criminal, counterterrorism, or counterintelligence investigation; interference with diplomatic relations; or danger to the life or physical safety of any person.”