This book explores how Global South states construct legal narratives in the advisory proceedings on climate change before the International Tribunal for the Law of the Sea (ITLOS). It frames climate change as a matter of ‘community interest’ that demands collective action and legal interpretation within international institutions. The study argues that the narratives advanced by Global South states are not merely legal texts but may be embedded within broader political contexts and informed by historical inequalities, colonial legacies, and disproportionate climate vulnerabilities. Drawing on a mixed-method approach, the research examines whether and how these narratives reflect shared demands for climate justice and align with political positions expressed in multilateral arenas, such as the Conferences of the Parties (COPs) of the United Nations Framework Convention on Climate Change (UNFCCC). By analysing Global South states’ submissions and discourses, the book sheds light on how legal language operates as a strategic tool of foreign legal policy, shaping and reflecting international legal development through institutionalized adjudication.