Governments can, and commonly do, adopt policies whose environmental implications completely overshadow the impacts of individual development projects as assessed by projectscale environmental impact assessment. Environmental assessment (EA) of government policies is therefore as important to sustainable development as EA of projects. One way to achieve routine policy EA is through a formal legal framework which covers: definition of a policy; screening criteria and exemptions; public advertisement, exhibition and submission; technical standards for environmental assessment; substantive criteria for weighing public environmental costs against public benefits; and provisions for third-party standing. The aims of such a framework would be to make policy EA a routine part of policy formulation.