Global climate constitutionalism is seen as a possible legal answer to the social and political unwillingness of states to effectively tackle climate change as a global problem. The constitutionalisation of international climate law is supposed to ensure greater participation of non-state actors such as NGOs or individuals and a rollback of state sovereignty where states do not care about meeting their climate commitments. This book addresses the question of whether non-state actors such as NGOs or individuals create international climate law through so-called climate change litigation. Against the background of Peter Häberle's theory of the "open society of constitutional interpreters", four selected cases (Urgenda v Netherlands, Leghari v Pakistan, Juliana v United States of America, Future Generations v Colombia) are used to examine how actors not formally recognized as subjects of international law (re)interpret national and international law and thereby contribute to theconstitutionalisation of the international climate law regime.