The spying agencies are as accountable as any other agencies. They do what they do at the behest of the public's elected representatives.
"An internal investigation by the C.I.A. has found that its officers penetrated a computer network used by the Senate Intelligence Committee in preparing its damning report on the C.I.A.’s detention and interrogation program. "
https://mobile.nytimes.com/2014/08/01/world/senate-intellige...
You do know they have the worst dirt on everyone right?