Here's a clue:
USA Today has published an extraordinary interview with three former NSA employees who praise Edward Snowden's leaks, corroborate some of his claims, and warn about unlawful government acts....
- Congressional overseers "have no real way of seeing into what these agencies are doing. They are totally dependent on the agencies briefing them on programs, telling them what they are doing."
- Lawmakers "don't really don't understand what the NSA does and how it operates. Even when they get briefings, they still don't understand." --quoted at Vox Populi.
Read the rest of the Vox link, by the way. Snowden wasn't kidding.