The UK's most secretive court has ruled that British spies acted unlawfully in accessing millions of personal communications gathered by America.
It's the first time the Investigatory Powers Tribunal has ruled against the security services.
The court said that until December, the government's intelligence agency GCHQ did not make it clear enough to the public how it intercepted, stored and shared data from mass internet surveillance.
More transparency has since made the process legal.
Journalist Belle Lupton joined London Live to explain what ruling means.