Privacy International filed today the complaint with the Investigatory Powers Tribunal, Britain's interception watchdog, over allegations that the National Security Agency and its British counterpart GCHQ are spying on one another's citizens and sharing the information without adequate legal oversight.
Both intelligence agencies have been shaken by the publication of leaked documents, which have revealed extensive details about their globe-spanning information-gathering effort.
In the United States, groups including the American Civil Liberties Union say they are suing. In Britain, rights group Liberty has also filed a complaint over the spying.