Plan B Earth and Others v. UK Prime Minister

By Leon Qiu

Law appliedDomestic Environmental Law
Key wordsUnited Kingdom; Court of First Instance; Court of Appeal; Supreme Court; Environmental Law.

Case Information:

Court(s): Queen’s Bench Division (Divisional Court), Court of Appeal (Civil Division), the Supreme Court

Dissenting judgement? No

Filing date: 2018

Last Update: 2020

Status: Decided


Divisional Court

Whether the UK Government’s policy supporting the expansion of Heathrow airport, adopted under the Planning Act 2008 (“PA 2008”), provided adequate consideration to the UK’s climate change commitments under the Paris Agreement.

Court of Appeal (On Appeal) 

Whether the Divisional Court erred in finding that Secretary of State (“the defendant”) had not acted unlawfully in designating the policy without considering the Paris Agreement.

The UK Supreme Court (On appeal) 

  1. Whether the government’s commitment to the Paris Agreement (particularly the ministerial statements given in March 2016 prior to signing the Paris Agreement) constituted part of ‘Government policy’ under s 5(8) of PA 2008. 
  2. Whether the defendant had breached his duty under s 10(3)(a) of PA 2008 by failing to have proper regard to the Paris Agreement when designating the policy. 
  3. Whether the Secretary of State had breached his duty under the SEA Directive [1], due to making no reference to the Paris Agreement in the environmental report required under the SEA Directive
  4. Whether the Secretary of State had breached his duties under the PA 2008 s 10(2) and 10(3) by failing to take into consideration the post-2050 and non-CO2 emissions grounds.


In June 2018, the defendant declared a policy supporting the development of a third runway at Heathrow Airport, designated under s 5 of PA 2008 through Airports National Policy Statement (“ANPS”). Plan B Earth and others (collectively “the claimants”) contested the designation decision by judicial review in multiple ways, including grounds of climate change. The Divisional Court’s ruling in this regard was later appealed to the Court of Appeal and was reversed. 


The Claimants:

The Secretary of State failed to consider the Paris Agreement through designating the ANPS. Subsequently, the defendant has violated the SEA Directive on the assessment of the effect of certain plans and programmes on the environment. 

The Defendant

The correct approach when designating the ANPS was to consider existing domestic legal obligations, such as the Climate Change Act 2008 (“CCA 2008”) and policy commitments, which the ANPS had done. While the Paris Agreement was not ignored, it was deemed irrelevant and should not be  considered in the context of ANPS. 


Divisional Court:

The Divisional Court dismissed the application on the grounds that:

  1. Any obligation imposed on the UK Government by the Paris Agreement did not affect domestic law.
  2. Neither Government Policy nor the Paris Agreement could override or undermine the policy as set out under CCA 2008. Therefore, the Secretary of State did not err in taking the CCA 2008 targets into account and not considering the Paris Agreement when designating ANPS.

Following the dismissal, several parties to the case appealed.

Court of Appeal, Civil Division:

The Court of Appeal reversed the decision of the Divisional Court. The Court held that:

  1. The Defendant’s designation of ANPS unders 5(1) of the 2008 Act was unlawful. The defendant should have taken the 2015 Paris Agreement into account, but failed to do so. 

Section 5(8) of the PA 2008 required the ANPS to explain how the defendant had taken Government Policy into account. The term ‘Government Policy’ was not to be limited to the legal requirements of the CCA 2008. The Divisional Court had erred in concluding that the defendant had been forced to take a position that was inconsistent with their statutory obligations required under the CCA 2008. The CCA 2008’s words did not require the defendant to act in accordance with any particular policy; rather, they required consideration of policy and explain how it had been considered. This consideration and explanation is missing in the present case [2].

By the time of the ANPS designation, the Government’s commitment to the Paris Agreement had been part of the ‘Government policy.’ This resulted from the UK’s solemn ratification and clear reiterations of the Government policy of adhering to the Paris Agreement. It did not follow that the defendant was obligated to act according to the Paris Agreement or achieve any particular outcome; the only obligation was to take the Paris Agreement into account in the decision-making process [3].

  1. The Secretary of State received legal advice that they may not only disregard the Paris Agreement but that they had been legally obliged to ignore it altogether. This was a clear misdirection of law. There had been a material misdirection of law at a crucial point in the process, causing confusion that reverberated throughout the decision-making process. The decision produced was thus unsafe [4].

The Court of Appeal therefore found in favour of the Claimants. Following this decision, the Government appealed to the UK Supreme Court. 

The UK Supreme Court:

The UK Supreme Court reversed the decision of the Court of Appeal and found that the Divisional Court had been correct in finding in favour of the Government and not the claimants. The UK Supreme Court held that it was wrong to hold that the defendant failed to take the Paris Agreement into account. The defendant lawfully exercised discretion as to how much weight to attribute to it. 

  1. On issue (1), the words ‘Government policy’ should not be applied in their ordinary sense. The criteria for a ‘policy’ is the absolute minimum required to be satisfied for a statement to constitute ‘policy’ under PA 2008 s 5(8). [5] Parliament could not have intended to create a bear trap and require ministers to consider any ministerial statements [6]. When the defendant had designated the ANPS, the Government’s relevant approach had still been developing, so there was no established policy other than what was included in the CCA 2008. The PA 2008 s 5(8) challenge thus failed [7].
  2. On issue (2), as to whether the Secretary of State had acted irrationally in omitting to take the Paris Agreement further into account or to give it greater weight than he actually had done [8]. According to evidence, the Secretary of State had considered whether he should take the Paris Agreement into account beyond the extent to which it was already reflected in the CCA 2008 obligations, and had concluded that it would not be appropriate. The reason was that the international obligations of the UK under the Paris Agreement had been sufficiently considered in the designation of the ANPS. Such an opinion was rational.
  3. On issue (3), evidence showed that the Paris Agreement had been considered when drafting the environmental report, and the defendant had decided in the exercise of his discretion to not make a distinct reference to it [9]. The defendant had not breached any of his obligations under the SEA Directive in such processes [10].
  4. On issue (4), the defendant had not acted irrationally in not attempting in the ANPS to assess post-2050 emissions against policies which had yet to be determined.

Please find the full Divisional Court judgement here

Please find the full Court of Appeal judgement here

Please find the full Supreme Court judgement here

Last edited 27 May 2022; with thanks to the case editor, Olivia Amura.


[1] Directive 2001/42/EC of the European Parliament and of the Council of 27 June 2001 on the assessment of the effects of certain plans and programmes on the environment. 
[2] R (on the application of Plan B Earth Ltd) v The Secretary of State For Transport and others [2020] EWCA Civ 214, paras. 223–226.
[3] Ibid., paras. 228, 238.
[4] Ibid., para. 227.
[5] R (on the application of Friends of the Earth Ltd and others) v Heathrow Airport [2020] UKSC 52, paras 107, 106.
[6] Ibid., para. 105.
[7] Ibid., paras. 111, 112.
[8] Ibid., para 125.
[9] Ibid., para. 140.
[10] Ibid., para. 150.
Categories YCLD

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