Self governance is incompatible with states secrets, and only leads to abuse, corruption, and tyranny.
History is full of known abuses, and for every known abuse there is the potential for LOTS of unknown abuse.
One can say "well congress will hold them accountable" but along time ago congress passed a law to declassify everything around JFK assassination, yet multiple presidents after bring pressured by the CIA for "national security reasons" have refused to release all kinds of document in direct violation of that law.
the CIA, any other agency with the power to "classify" things, is a direct and ever present threat to not only liberty but the underpinning of democracy everyone claims to support.