Environmental principles proliferate in domestic international legal and policy discourse - from the polluter pays and precautionary principles to the principles of integration and sustainability - reflecting key goals of environmental protection and sustainable development on which there is apparent political consensus.a Environmental principles also have a high profile in environmental law, beyond their popularity as policy and political concepts, as ideas that might unify the subject and provide it with conceptual foundations or boost its delivery of environmental outcomes.aHowever, environmental principles are elusive concepts in environmental law - their meanings and legal functions are ambiguous, and they have varying histories in different jurisdictions.aThis book aims to deepen the legal understanding of environmental principles in light of recent legal developments.aTo this end, it analyses closely the increasing legal effects of environmental principles in different jurisdictions to demonstrate how they are in fact shaping and revealing innovative bodies of environmental law.a This analysis is a step forward in understanding a key feature of modern environmental law, as well as beingaa contribution to environmental policy debates and discussions internationally that rely heavily on environmental principles, including their supposed legal effects.