This timely book focuses on the EU-wide greenhouse gas emissions trading scheme for major sources. It combines legal and economic approaches and reviews the major revision of this scheme. A distinguished range of authors assess the experiences thus far and also consider future development from both theoretical and practical perspectives. They also discuss many design options, including auctioning, credit and trade, the inclusion of aviation emissions, and linking possibilities. Moreover, attention is paid to the role of legal principles, the role of case law, and to aspects of democratic accountability within an emissions trading scheme. Ways to avoid carbon leakage and the role of national climate policies are also discussed. This book makes clear that the economic efficiency and effectiveness of an emissions trading scheme depend to a large extent on the specific legislative choices, and hence the legislative design of such a scheme deserves meticulous attention.