>It would probably take another Snowden to get any evidence on it.
And I think that the possibility of another Snowden for this requires that there be some functioning mechanism by which requests to do this are centrally cleared, or even recorded, which I don't think is a sure thing. I see it just as likely that different agencies and departments within them are operating under a lot of different standing blanket orders in the form of legal interpretations, and that once a parallel construction is created, the records of any alternate explanation are destroyed (or were never created.)
Not necessarily - some policeman or policewoman doing this or seeing her peers do that can one day wake up and say - I had enough with violating rights of Americans, I'm just going to document everything we're doing that is wrong and then publish it, and be whatever it will be. Fat chance, I know, but who thought it could happen in NSA before it did? You never know. And after that happens, of course higher-ups will deny that happened, but once the cat is out of the bag and the attention of the society has been captured that would be a different story altogether than now. It would move from "those crazy libertarians are breaking out their tinfoil hats again" to "omg omg police is really doing it right under our noses! It could even happen to me!"
For once, somebody could get and publish all those training manuals - unredacted, with all the juicy details. With it being this entrenched, something must be written down - you can't rule system this vast on lore alone.
And I think that the possibility of another Snowden for this requires that there be some functioning mechanism by which requests to do this are centrally cleared, or even recorded, which I don't think is a sure thing. I see it just as likely that different agencies and departments within them are operating under a lot of different standing blanket orders in the form of legal interpretations, and that once a parallel construction is created, the records of any alternate explanation are destroyed (or were never created.)