From the UK:
The "Big Brother" comprehensive national database system feared by many MPs has been built behind their backs over the last decade, and even has a name for its most intrusive component: a central London national phone and internet tapping centre called PRESTON.
Duncan Campbell, theregister.co.uk
The only way to keep intelligence services under control and working for the people appears to be to create a dedicated agency with directly elected officials* that have 100% access power comparable to a permanent search warrant and subpoena power against the intelligence agencies (and the authority to take the police with them to enforce this access by force if necessary). And of course they would need to be authorised to publish whatever they want, the intelligence services' ability to simply classify their fuck-ups is
related: 2013-09 Effective oversight over bureaucracies
*: With at least two elected officials of equal power, the one with the most and the one with the second-most votes. This way even a submissive, authority-believing public could end up having at least one true champion for civil liberties in that office.