Is opposition to third runway at Heathrow Airport grounded?

On 16 December 2020, the Supreme Court overturned an earlier decision by the Court of Appeal, in February 2020, which had blocked the construction of a third runway at Heathrow Airport. The lower court had found in favour of the appellants - Friends of the Earth and others - on the basis that the Secretary of State for Transport’s decision to permit construction of the runway had failed to take full account of the UK Government’s commitments to mitigate climate change under the 2015 Paris climate accord.

The Supreme Court’s decision in this case now means that, as a matter of law, the airport can seek a development consent order, which is required for large infrastructure projects in the UK. Whether or not the runway project does go ahead remains to be seen. However, the Supreme Court’s decision now sets aside a legal precedent that many had hoped would provide a powerful platform for ensuring that Government policy on climate change directly informs transport and other infrastructure planning.


The Paris Agreement on Climate Change, signed on 12 December 2015 and ratified on 17 November 2016 by the UK government, sets out prescribed international climate goals which all signatories to the agreement seek to achieve, with the ultimate aim of achieving net-zero greenhouse emissions by the second half of the 21st century. The agreement establishes ambitious climate aspirations of limiting global warming to well below 2 degrees Celsius, preferably to 1.5 degrees Celsius, compared to pre-industrial levels.[1]

The Airports National Policy Statement (ANPS) is the national policy framework underpinning the planned expansion of Heathrow Airport, and more specifically, the construction of the third North West Runway (NWR). On 26 June 2018, the Secretary of State designated the ANPS as national climate policy.[2]


The respondents (and others) challenged the ANPS on the basis of its failure to take account of the Paris Agreement by way of judicial review before the High Court.

On 1st May 2019, the High Court dismissed their application for judicial review, [3] but the Court of Appeal subsequently allowed their appeal in a judgment dated 27th February 2020 and held that the ANPS was unlawful.

Heathrow Airport Ltd were granted leave to appeal to the Supreme Court with the hearing taking place on 7 and 8 October 2020.


The Supreme Court allowed the appeal unanimously, citing four reasons for the judgment:

Government policy

Section 5(7) Planning Act sets out that: a national policy statement must give reasons for the policy set out in the statement. Furthermore, subsection (8) states that: the reasons must (in particular) 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. The co-respondents, Plan B Earth, argued that the reasons required by section 5(7) needed reference to the Paris Agreement as this was part of Government policy.

Provisions in sections 1 and 4 Climate Change Act 2008 impose obligations on the Government to establish carbon budget targets. The UK’s sixth carbon budget was published on 9 December 2020 and has imposed stricter national climate targets than those prescribed by the Paris Agreement.

The Court held there was no established policy beyond that already encapsulated in the CCA 2008. The Government followed the advice of the CCC.[4]

Sustainable development

Sections 10(2) and 10(3) Planning Act 2008 enact duties upon the Secretary of State to designate national policy frameworks with the purpose of promoting the goal of sustainable development.

The Court found that the UK’s domestic climate obligations had been considered in formulating the ANPS and that it was inappropriate to consider the Paris Agreement in this exercise.[5]

Post-2050 and Non-CO2 Emissions

The Secretary of State did not act unreasonably in deciding not to consider post-2050 emissions by reference to future policies which were not yet formulated.

The Court held that future development consent applications would be assessed against the current emissions targets and climate policies effective at that time, rather than the time of designation of the ANPS.[6]

Environmental Report

Section 5(3) Planning Act 2008 obliges the Secretary of State to produce an appraisal of sustainability regarding national policy frameworks.

The Environmental Assessment of Plans and Programmes Regulations 2004 require the Secretary of State to produce an environmental report with respect to major plans and proposals such as the Heathrow Airport expansion.[7]

The appraisal of sustainability noted the UK’s climate commitments under the Climate Change Act and as a result, the Secretary of State took sufficient account of the UK’s international obligations as part of the Paris Agreement.[8]


The effect of this ruling places additional prominence on the UK’s climate policy in light of the CCC’s publication of the sixth carbon budget. This ruling will undoubtedly raise doubts over whether domestic obligations including those set out in the Climate Change Act 2008 will be achieved.

Furthermore, the impact of the Supreme Court ruling means that the expansion of Heathrow Airport through the construction of the NWR may, in principle, commence.

However, notwithstanding the Supreme Court’s decision, there may still be procedural blocks to the NWR project. Since the date of the Court of Appeal judgment at the beginning of this year the Government has created stricter pledges to cut emissions in the UK, including, earlier this month to cut carbon emissions by 68% by 2030. Against these renewed commitments, in the context of a pandemic significantly reducing air traffic, and as hosts of COP26 in November 2021, it may be that despite the Supreme Court’s decision, a third runway at Heathrow remains a paper project only.

Hausfeld London, partnering with the Good Law Project have written to the Government requiring that it reviews the ANPS or face legal proceedings, citing the Government’s new net-zero commitment in section 1 of the Climate Change Act 2008. The Government is due to respond by 18.1.2021.

With thanks to intern Alexander Batty for co-authoring this piece.


[1] R (on the application of Friends of the Earth Ltd and others) v Heathrow Airport Ltd [2020] UKSC 52

[2] Planning Act 2008, section 5(1)

[3] R (Spurrier and Others) v Secretary of State for Transport [2019] EWHC 1070 (Admin) 

[4] [2020] UKSC 52, para 111

[5] [2020] UKSC 52, para 88

[6] [2020] UKSC 52, para 157

[7] SI 2004/1633

[8] [2020] UKSC 52, para 149