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 2021 introduces a new regime of environmental principles and governance to fulfil 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 body – the Office for Environmental Protection – with wide-ranging enforcement powers, and a new form of litigation: environmental review. In addition, the Act extends and develops environmental law sectorally in a number of significant ways, including by on waste collection, biodiversity net gain, conservation covenants and due diligence on forest risk commodities. This new book will provide a practitioners’ guide to the implementation of the Act including related legislation and regulations made under it.