Britain's GCHQ eavesdropping agency breached fundamental human rights by intercepting and harvesting vast amounts of communications, the European Court of Human Rights ruled on Tuesday.
Revelations by former National Security Agency contractor Edward Snowden showed that GCHQ and the U.S. National Security Agency were sucking up vast amounts of communications from across the world,including on their own citizens.
The Strasbourg-based court ruled in a case known as "Big Brother Watch and Others vs. the United Kingdom" that Britain had breached the right to respect for private and family life communications and the right to freedom of expression with its bulk intercept regime.
The regime for obtaining communications data from service providers also violated human rights, the court said, though it added that bulk interception in itself was not illegal.
The law which allowed the bulk interception has since been replaced by new legislation which the British government says provides greater oversight.
"This judgment confirms that the UK’s mass spying breached citizens’ rights to privacy and free expression for decades," said Silkie Carlo, director of Big Brother Watch.
"We welcome the judgment that the UK’s surveillance regime was unlawful, but the missed opportunity for the Court to prescribe clearer limitations and safeguards means that risk is current and real."
Civil liberties campaigners,including Big Brother Watch and Amnesty International, had brought the case as they believed their communications had been harvested by bulk interception unnecessarily and without due process.
The British government argued that bulk interception was critical for national security and had enabled it to uncover grave threats. Essentially, London argued that it had to harvest vast amounts of data to find the threats.
The court ruled that a bulk interception regime did not in itself violate human rights but that it should have proper safeguards.
Britain said it had established an international benchmark with its "unprecedented transparency" over data and privacy.
"The UK has one of the most robust and transparent oversight regimes for the protection of personal data and privacy anywhere in the world," a government spokeswoman said, adding that the 2016 Investigatory Powers Act has already replaced the earlier legislation that was the basis of the challenge.
The court ruled that there had been no violation of rights by requests for intercepted material from foreign intelligence agencies.
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