Supreme Court overturns block on Heathrow’s expansion

6 min read

In its recent decision in R (on the application of Friends of the Earth Ltd and others) v Heathrow Airport Ltd, the Supreme Court reversed the Court of Appeal's decision that the planned expansion of Heathrow Airport was unlawful on climate change grounds, and determined that the UK Government had taken proper account of the UK's climate change commitments.



In June 2018, the UK Government supported Heathrow Airport Ltd's ("Heathrow Airport") longstanding plans to develop a third runway through the Airports National Policy Statement ("ANPS"), which had been designated by the Secretary of State for Transport ("SoS") under section 5 of the Planning Act 2008 ("Planning Act") for nationally significant infrastructure projects.

The Planning Act requires these types of policy statements to: (i) explain how the infrastructure project has taken account of UK Government policy on climate change (section 5(8)); and (ii) demonstrate that the policy is in line with the objective of achieving sustainable development, in particular, mitigating and adapting to climate change (section 10). Specifically, sections 10(2) and (3) of the Planning Act require the SoS to designate national policy frameworks with the aim of contributing to the achievement of sustainable development.

Several environmental campaigners, including Friends of the Earth Ltd and Plan B Earth ("Plan B"), challenged the lawfulness of the SoS's designation on a number of climate change-related grounds, including that the ANPS had not considered the UK Government's commitments under the Paris Agreement (ratified by the UK Government in November 2016). In 2019, the Divisional Court dismissed these claims, but in February 2020, the Court of Appeal overturned part of the Divisional Court's ruling and held that the SoS had acted unlawfully in failing to take the Paris Agreement into account when designating the ANPS. As a result, the Court of Appeal determined that the ANPS was of no legal effect (see here).

While the SoS did not appeal the Court of Appeal's decision, Heathrow Airport - which had already made significant investment in promoting the runway expansion scheme - decided, and was granted permission, to appeal the Court of Appeal's decision.



On 16 December 2020, the Supreme Court unanimously overturned the Court of Appeal's decision and allowed Heathrow Airport's appeal on all four grounds. The Supreme Court outlined four key reasons for the judgment:1

  1. Government policy: In contrast to the Court of Appeal's view, the Supreme Court held that for section 5(8) of the Planning Act to operate sensibly, the phrase "government policy" should be given a "relatively narrow meaning so that the relevant policies can readily be identified".It considered that "the epitome of "Government policy" is "a formal written statement of established policy" but, in some exceptional circumstances, may extend beyond such written statements and, where it does, there should be clear limits on what would constitute a policy.3 Accordingly, as the domestic implementation of the Paris Agreement commitments were still in development, the formal ratification of the Paris Agreement did not mean that it constituted "government policy" for the purposes of the Planning Act.4
  2. Sustainable development: The Supreme Court rejected the argument that the SoS had breached the duty outlined in sections 10(2) and (3) of the Planning Act by failing to have proper regard to the Paris Agreement when designating the ANPS (on the basis that the SoS was obliged to "have regard to the desirability of … mitigating, and adapting to, climate change" when discharging his duty under section 10(3) of the Planning Act).Indeed, the Court found the ANPS was structured in a manner to ensure that when Heathrow Airport applied for development consent to construct the runway, it would have to show, at that stage, that the runway expansion would be compatible with the up-to-date requirements under the Paris Agreement and the Climate Change Act 2008.6
  3. Environmental report: The Supreme Court dismissed the respondents' complaint that the appraisal of sustainability accompanying the ANPS (required by section 5(3) of and the Strategic Environmental Assessment Directive7) was defective because it did not refer to the Paris Agreement.The decision as to whether the information in an environmental report provides a sound and sufficient basis for public consultation is a matter that falls within the SoS's discretion, and the Supreme Court agreed with the Court of Appeal that the role of the court is not to restrict the exercise of this discretion more tightly than is necessary. Accordingly, the SoS's decision will only be found unlawful if it is one that no reasonable decision-maker would have made.9
  4. Post-2050 and non-CO2 emissions: The Supreme Court dismissed the argument that the SoS had separately breached his section 10 duty by failing to have regard to (i) the effect of greenhouse gas emissions created by the new runway after 2050; and (ii) the effect of non-CO₂ emissions.10 Instead, it determined that the SoS's approach to these issues was rational and lawful in all respects.



Following the Supreme Court's judgment, Heathrow Airport is now entitled to apply for planning permission for its third runway. However, notwithstanding that the Supreme Court's decision to overturn the Court of Appeal's judgment could have wide-reaching implications for infrastructure projects in the UK, challenges for the runway expansion plan remain. In particular, the project still requires a development consent order, which will require consideration of the more stringent climate change pledges made by the UK Government since the ANPS's approval in 2018. These include the UK Government's target to achieve carbon neutrality by 2050 (set in June 2019), as well as its recent (December 2020) pledge to cut emissions by 68% by 2030.11

Heathrow Airport may also still face further legal challenges as the prevalence of climate change-related actions continues to rise. Shortly after the judgment was rendered, Plan B announced that it intends to take the judgment to the European Court of Human Rights.12 Further, on 12 December 2020, Plan B served a pre-action letter on the UK Government alleging that its failure to develop a plan to tackle climate change was a violation of human rights and of both domestic and international law.13

Looking to the future, there is the potential for increased scrutiny of proposed infrastructure projects through the establishment of the Office for Environmental Protection ("OEP"), as created by the Environment Bill. The OEP is a new independent regulator that will scrutinise all government policy to ensure the environment is at the heart of decision making. Crucially, it will have the power to run its own independent investigations and enforce environmental law, including taking Government and other public bodies to court where necessary. Courts would then have the power to issue fines, should they deem it appropriate. While the OEP has the potential to hold the government to account, its effectiveness remains to be seen, with some commentators suggesting that the OEP will not have the 'teeth' it needs, as it will not be able directly to fine the Government if it breaches its environmental responsibilities.


1 R (on the application of Friends of the Earth Ltd and others) (Respondents) v Heathrow Airport Ltd (Appellant)[2020] UKSC 52. On appeal from: R (on the application of Plan B Earth) v Secretary of State for Transport [2020] EWCA Civ 214.
2 Paragraph 105.
3 Paragraph 106.
4 Paragraph 108.
5 Paragraph 115.
6 Paragraphs 87-124.
7 Council Directive 2001/42/EC of 27 June 2001 (the "SEA Directive") as transposed into domestic law by the Environmental Assessment of Plans and Programmes Regulations 2004 (SI 2004/1633).
8 Paragraph 139.
9 Paragraph 144.
10 Paragraphs 151-166.


Sam White (White & Case, Trainee Solicitor, London) contributed to the development of this publication.

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