Plan B Earth v Secretary of State for Transport [2020] EWCA Civ 214

The UK Court of Appeal cancelled the government’s decision to develop a third runway in Heathrow Airport on the ground that the strategic environmental assessment had not taken the adoption and ratification of the Paris Agreement into account.
The main argument accepted by the Court was that the Planning Act 2008 s.5(8) requires a national policy statement to “take … account of Government policy relating to the mitigation of … climate change.” The plan at issue took account of the UK’s Climate Change Act 2008 (based only on a 2C target), but not of the Paris Agreement (which defined a “well below” 2C target and a 1.5C target). In the Court’s view, the Paris Agreement constituted government policy.
The Court also accepted that taking account of the Paris Agreement was necessary under the EU Directive on Strategic Environmental Assessment, as Annex I requires States to take into account any international objectives on environmental protection.
The case highlights the role that environmental assessment procedures can play as a tool for climate change mitigation.
However, the Court did not carefully discuss the question of the relevance of the Paris Agreement. This treaty does not provide any specific objective for the UK (or for international civil aviation). While the Court seems concerned by a change in the global temperature target (from 2C, to “well below” 2C and towards 1.5C), it is unclear what, if any, significance this has for the mitigation objectives applicable to the UK or to international civil aviation.
The UK government has apparently decided not to appeal against this judgement. The government could very well carry out a new environmental assessment procedure for the same project, addressing the procedural flaw identified by the Court of Appeal. PM Johnson has however clearly indicated his opposition to the project.