Brexit involves a break from the environmental regulation regime of the EU, including the oversight by the European Commission. A large proportion of existing environmental law and policy in the UK derives from the EU, with its implementation largely monitored and enforced by EU institutions such as the European Commission. The Environment Act 2020 introduces a new regime of environmental principles and governance to fulfill the role that will be lost upon Brexit. The Act creates a new regime of environmental policy for the UK, together with a new system of targets, monitoring and reporting on issues such as air quality, water, waste and biodiversity. It also creates an entirely new regulator - the Office for Environmental Protection - with wide-ranging enforcement powers, and a new form of litigation: environmental review.