The UK spy agency GCHQ says it doesn't need a warrant to intercept and store all UK social media traffic, search history and webmail because it is headed offshore, so it's "foreign communications". It had kept this interpretation of English and Welsh law a secret until now, and only revealed it after a protracted legal battle with the excellent people at Privacy International and six other civil liberties groups, including Amnesty International, and ACLU.
Mr Farr did not reveal the extent to which GCHQ uses its power to intercept external communications.
In a statement, GCHQ said all its work "is carried out in accordance with a strict legal and policy framework which ensures that our activities are authorised, necessary and proportionate".
But civil liberty groups were outraged by the revelations.
James Welch, legal director of human rights group Liberty, said: "The security services consider that they're entitled to read, listen and analyse all our communications on Facebook, Google and other US-based platforms.
"If there was any remaining doubt that our snooping laws need a radical overhaul there can be no longer."
Meanwhile Eric King, deputy director of Privacy International said the revelation showed that spy agencies operated under their own laws.
"Intelligence agencies cannot be considered accountable to parliament and to the public they serve when their actions are obfuscated through secret interpretations of Byzantine laws."