The European Union (EU) has had a profound effect on UK environmental policy and governance. The EU provides treaty-based principles to underpin and inform new policy development and a well-developed system of monitoring and enforcement to ensure it is implemented. The EU’s system of environmental governance provides a set of structures that establishes minimum common standards across the UK. These structures have allowed the devolved nations to develop their own policies, some with a higher level of ambition than the UK’s. EU membership, therefore, provides a common framework that enables both transboundary cooperation and local policy innovation. Brexit consequently represents a major change to environmental governance in the United ...