The lawsuit, filed today by Privacy International, joins a slew of legal challenges spawned by Snowden's disclosures. Other rights groups have filed lawsuits against the agency for its mass intercept of data flooding back and forth across the world's fiber optic cables and satellites.
Unusually, Privacy's lawsuit challenges GCHQ's ability to hack into smartphones and computers, which it calls "potentially far more intrusive than any other current surveillance technique."
Richard Aldrich, the author of a book on GCHQ, said the agency worried about such lawsuits, explaining that judges were "much more unpredictable in this area" than a decade ago.