This book discusses various aspects of the concept of "sustainability", from a legal, ethical and public choice perspective.The context of sustainable development went through considerable changes since its ‘official’ opening in the 80s. The original meaning referred to the right of development which must however be restricted by the interests of present and future generations. After the Rio+20 process, parallel with the adoption of the 7th EAP of the EU and many national sustainability strategies, the actual content and interpretation of the principle is examined, with a special focus on its possible implementation and the main driving forces. The book provides a general survey on the contemporary ideas of interpretation, focusing on sustainable development law. Ethical and legal fundamentals and the possible legal substance are presented. Examples of international law – from ICJ judgments to Mekong River – demonstrate that the concept is significant in international treaties; however it is a question as to how this can meaningfully contribute to the preservation of the Earth’s fragile ecosystem. The book has a special focus on EU policy and law, introducing the serious conceptual change from sustainable development to sustainable growth and also examining the appearance of the concept in primary law, secondary law and judicial practice, to embrace the likelihood of implementation. The book also discusses the potential motivations of sustainability in governance, examines the compliance issues in international environmental law, focusing on the choices made not by nations as unitary rational actors but by the individual decision-maker, groups of decision-makers, also looking at interactions among domestic interest groups. The model uses the public choice theory, supposing that the decision about the compliance at large depends on the benefit and cost of the projects.