This case analysis considers the Court of Appeal’s decision in R (Plan B Earth and ors) v Secretary of State for Transport [2020] EWCA Civ 214, which followed the High Court challenge to the Secretary of State’s designation of the UK Airports National Policy Statement. The Court of Appeal found that the Secretary of State’s failure to take into account the UK’s commitment to the Paris Agreement when carrying out his duties under the Planning Act 2008 was unlawful. While permission to appeal this decision has been granted, it remains a notable judgment. The Plan B Earth case confirms the interaction between the UK’s climate change commitments and the statutory framework of the UK’s planning system. It also highlights the complexity of the Court’s institutional role in the context of environmental problems. Analysing the implications of this decision through a policymaking lens risks overlooking the role of public law principles that shaped the Court’s reasoning, defining the relationship between the Paris Agreement and the Planning Act
