In this Part of the book we embed environmental law and policy in a European context. This context is made up of a complex of European law and policy-making institutions and adjudication and enforcement bodies. The relationship between European Union (EU) law and policy in this context is highly intricate and politically charged (both at the EU and Member State levels) such that the line between non-binding legal instruments and areas of policy ‘hardened’ up over time to create firm obligations is at times difficult to draw. Key principles (for example precaution) also appear to straddle the law–policy divide: although their legal nature is somewhat uncertain, they do feature in the European Community (EC) Treaty's Title on the Environment, and the Court of First Instance (CFI) and the European Court of Justice (ECJ) have been prepared to assess the actions of both the EU institutions and the Member States by reference to them. The status of ‘principles’, and the absence of a hard definition, both makes them important policy guidance and suggests that they are not likely to play a very strong role in judicial review. A sense of the complexity of the institutional arrangements, and the relationship between law and policy, is provided by Damian Chalmers.