Leading judges gave their ruling on Wednesday morning following separate judicial reviews of the Government’s decision to approve the plans, brought by a group of councils, residents, environmental charities and Mayor of London Sadiq Khan.
Lawyers for some of the claimants argued at a hearing in March that the plans would effectively create a “new airport” with the capacity of Gatwick and have “severe” consequences for Londoners.
Outlining the case on behalf of five London boroughs, Greenpeace and Mr Khan, Nigel Pleming QC said the plans could see the number of passengers using the airport rise to an estimated 132 million, an increase of 60%.
The case was brought against Transport Secretary Chris Grayling by local authorities and residents in London affected by the expansion and charities including Greenpeace, Friends Of The Earth and Plan B.
The campaigners claim the Government’s National Policy Statement (NPS) setting out its support for the project fails to properly deal with the impact on air quality, climate change, noise and congestion.
If the claimants succeeded with their argument that the NPS is unlawful and should be quashed, the Government would have had to start the process again and put it to another vote in Parliament.
Friends Of The Earth and Plan B argued Mr Grayling failed to take enough account of the impact on air quality when reaching the decision to approve the third runway.
Lawyers representing Mr Grayling said the claimants’ case was “unarguable” and “premature”, as they will all have the opportunity to make representations at a later stage in the planning process.
Support from Labour MPs helped push through the proposals to expand Europe’s busiest airport with an overwhelming majority of 296 in a Commons vote in June last year.
Mr Grayling said at the time that the new runway would set a “clear path to our future as a global nation in the post-Brexit world”.
Construction could begin in 2021, with the third runway operational by 2026.
As with any major infrastructure project, we have been anticipating legal challenges and will robustly defend our position
Demonstrators were due to gather outside the court ahead of the ruling by Lord Justice Hickinbottom and Mr Justice Holgate.
Speaking ahead of the judgment, Paul McGuinness, chairman of the No 3rd Runway Coalition, said: “Expansion of Heathrow airport would be a major policy error for the UK.
“The consolidation of this aviation behemoth in the already well-endowed south east would further entrench the regional imbalance of the economy.
“It would be an environmental disaster.”
A Department for Transport spokeswoman previously said: “Expansion at Heathrow is a critical programme which will provide a boost to the economy, increase our international links and create tens of thousands of new jobs.
“As with any major infrastructure project, we have been anticipating legal challenges and will robustly defend our position.”
A Heathrow spokeswoman previously said: “Our work in delivering Britain’s new runway will continue in tandem with this process following overwhelming support in Parliament.
“We remain focused on the work needed for our development consent order submission in 2020 and we are getting on with the delivery of this project which will benefit the whole of the UK.”