The Investigatory Powers Tribunal ruled today that the UK intelligence services acted unlawfully in their sharing of intelligence with the NSA prior to December 2014.

The case was brought to the Tribunal, which rules on intelligence matters, by the organisations Privacy International, Bytes for All, Liberty and Amnesty International.

The basis of the ruling is that the way in which intelligence sharing between GCHQ and the US intelligence services was kept secret prior to that date contravenes human rights. That includes the Tempora programme, by which the UK intercepts data passing through the transatlantic fibre-optic cables that carry much of the world's internet traffic, and warrantless access to data harvested by the NSA's Prism and Upstream programmes.

However, those same activities are now deemed to be legal. Following a limited disclosure by UK intelligence about its methodology with respect to information sharing with the US, on December 5th the IPT ruled that the cooperation between GCHQ and the NSA could continue.

Privacy International welcomed today's ruling, but said it does not go far enough since the activities are continuing as before.

"For far too long, intelligence agencies like GCHQ and NSA have acted like they are above the law. Today's decision confirms to the public what many have said all along - over the past decade, GCHQ and the NSA have been engaged in an illegal mass surveillance sharing program that has affected millions of people around the world," said deputy director Eric King in a statement.

"We must not allow agencies to continue justifying mass surveillance programmes using secret interpretations of secret laws. The world owes Edward Snowden a great debt for blowing the whistle, and today's decision is a vindication of his actions," he said, adding that more now needs to be done to put pressure on the authorities.

"The only reason why the NSA-GCHQ sharing relationship is still legal today is because of a last-minute clean-up effort by Government to release previously secret 'arrangements'. That is plainly not enough to fix what remains a massive loophole in the law, and we hope that the European Court decides to rule in favour of privacy rather than unchecked state power."

James Welch, legal director for Liberty, said his organisation will continue the battle through the European courts.

"We now know that, by keeping the public in the dark about their secret dealings with the National Security Agency, GCHQ acted unlawfully and violated our rights. That their activities are now deemed lawful is thanks only to the degree of disclosure Liberty and the other claimants were able to force from our secrecy-obsessed Government." Welch said.

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NSA-GCHQ data sharing was illegal - but they are free to carry on doing it