(Reuters) - British spies unlawfully retained people's intercepted data over almost five years, a tribunal said on Monday in a ruling that blamed “widespread corporate failure” at the domestic intelligence agency MI5 and the interior ministry.
The Investigatory Powers Tribunal, which did not mention specific cases or intelligence targets in its written judgment, said there had been “serious failings in compliance” by MI5 from late 2014 to April 2019.
Judge Andrew Edis also said the Home Office had failed to make "adequate enquiries" while approving the bulk surveillance warrants from 2016 until April 2019.
Human rights groups Liberty and Privacy International, which brought the legal action, said the ruling showed there had been years of rule-breaking by MI5, which was “overlooked” by the Home Office.
The case related to data obtained in "bulk" under the Investigatory Powers Act and previous legislation, which govern the interception of data for national security purposes.
Britain has been at the forefront of a battle between privacy and security since former U.S. security agency contractor Edward Snowden leaked details of mass monitoring tactics used by U.S. and British agents in 2013.
The Investigatory Powers Act provides vital tools to protect the public from criminals and terrorism, government and security officials say. But critics argue it grants police and spies some of the most extensive snooping capabilities in the West.
On Monday, Home Secretary Suella Braverman said the ruling related to "widespread corporate failings between the Home Office and MI5", which were "historic".
In a written statement to parliament, she added that the tribunal found that "it was not the case that MI5 should never have held the material at all, only that some small part of it had been retained for too long".
The tribunal also dismissed Liberty and Privacy International's wider challenge to the effectiveness of safeguards under the Investigatory Powers Act and its predecessor.
It also refused to quash any warrants that might have been unlawfully issued or direct MI5 to delete any unlawfully retained data as it “would be very damaging to national security”.
(Reporting by Sam Tobin; Editing by Andrew Heavens)