Climate change commitments lead to invalidity of Heathrow Airport extension policy

The UK's "Airports National Policy Statement: new runway capacity and infrastructure at airports in the south east of England" (ANPS), which provided for the extension of Heathrow Airport, has been held to be unlawful because the 2015 Paris Agreement was not considered in its development.

On 27 February 2020, the Court of Appeal of England and Wales (Court) unanimously ruled that the ANPS was invalid and its designation as a national policy statement was unlawful on several grounds involving climate change. These all relate to a failure to take into account the UK Government's commitment to the provisions of the 2015 Paris Agreement. Under the Paris Agreement, parties have committed to the long-term target of achieving net-zero greenhouse gas (GHG) emissions by 2050.

The ANPS was designated as a national policy statement for the purposes of the Planning Act 2008 (UK) (Planning Act) by the Secretary of State for Transport (Secretary) on 26 June 2018. Critically, the ANPS provided for the proposed expansion of capacity at Heathrow Airport by the addition of a third runway, which would significantly increase GHG emissions at the airport and from domestic and international air travel.

The controversial policy was subsequently subject to a number of challenges brought by five local authorities, the Mayor of London, Greenpeace Ltd, Friends of the Earth Ltd and Plan B Earth. Notably, the challenges relate to the legality of the administrative process followed by decision-makers,1 and the Court was not required to consider the merits of the ANPS.

Although there were a number of grounds of judicial review raised in the proceedings, the Court of Appeal upheld the appeal solely on the climate change grounds.

Firstly, the Planning Act2 required that the reasons for the policy set out in the ANPS "must ... include an explanation of how the policy set out in the statement takes account of Government policy relating to the mitigation of, and adaptation to, climate change". At the time of designation of the ANPS, the UK had legislated a 2050 target of achieving at least an 80% reduction in its GHG emissions from 1990 levels under the Climate Change Act 2008 (UK).3 The Secretary took this target into account but, on legal advice, chose not to take the Paris Agreement into account at all.4

The Court determined that the UK Government's commitment to the Paris Agreement was clearly part of "Government policy" by the time of the designation of the ANPS in 2018...