Professor Ian Walden comments on a complaint filed with the Investigatory Powers Tribunal - Britain’s interception watchdog – by the lobby group Privacy International. They allege that America’s National Security Agency and its British counterpart GCHQ are spying on one another’s citizens and swapping the intercepted information without proper oversight. Professor Walden says that the otherwise robust European Court tended to be “quite deferential to member states with regard to national security”. He adds: “I don’t think this is a slam-dunk.”