This book explores strategies for limiting transnational market failures, governance failures and constitutional failures impeding protection of the universally agreed sustainable development goals like climate change mitigation and access to justice and transnational rule-of-law. Can multilevel democratic and judicial protection of fundamental rights and public goods across frontiers be extended through plurilateral agreements? Can transnational economic and environmental constitutionalism be reconciled with 'constitutional pluralism' and with democratic constitutionalism depending on individual and democratic consent of free and equal citizens? Will judicial challenges (e.g. of EU carbon border adjustment measures) and countermeasures lead to further disruption of UN and WTO law? "This innovative book provides convincing analyses by leading practitioners and academics of multilevel governance of transnational public goods. It advocates the need for stronger involvement of civil society and democratic institutions. It shows why constitutionalism and constitutional economics offer appropriate methodologies for limiting market failures, government failures and constitutional failures. It thereby offers a glimpse of much needed optimism." Karl-Ernst Brauner, former Deputy Director-General of the World Trade Organization (WTO)