The court ruling could stall the £14 billion plan to expand Europe's busiest airport amid concerns over climate change, pollution and noise.
Campaigners have won a court ruling to block controversial plans for a third runway at Heathrow Airport on environmental grounds.
The ruling by England's Court of Appeal could stall a £14 billion plan to expand Europe's busiest airport amid concerns over climate change, pollution and noise.
It came after environmentalists and some local councils opposed Heathrow, which plans to build a third runway to increase capacity and reduce the use of holding patterns for arriving aircraft.
Parliament approved the plan in 2018, triggering a challenge from environmental groups who say the project conflicts with Britain's commitments to fight global warming. Local residents also complain about noise, pollution and increased congestion.
Heathrow said it would appeal the decision and was confident it could address the ruling's concerns.
Prime Minister Boris Johnson has long been an opponent of the expansion, and the ruling opens the possibility that he will use the decision as reason to reconsider the matter, and perhaps try to kill it. A spokesman for Johnson told reporters that Heathrow must still meet high environmental standards and demonstrate a "realistic" case for the project.
London Mayor Sadiq Khan, another longtime opponent of the project, described the decision as a victory for future generations.
"``The government must now finally see sense and abandon plans for a third runway at Heathrow," Khan said. ``We really are facing a climate emergency and it's about time the government started taking action to address this.''