Summary/Abstract
The escalating urgency of addressing climate change has prompted states to adopt innovative mitigation strategies, including Carbon Capture and Storage (CCS) technologies with transboundary applications. In February 2024, Indonesia and Singapore signed a Letter of Intent (LoI) to initiate bilateral cooperation on cross-border CCS, marking a significant development in regional carbon governance in Southeast Asia. This article analyzes the legal implications of this cooperation from the perspective of international law, with particular emphasis on the potential development of a binding bilateral agreement grounded in existing international legal frameworks. The central inquiry focuses on how the Indonesia–Singapore initiative contributes to the formulation of a transboundary legal framework for CCS and examines the relevant international legal principles and obligations that must be addressed. Employing a normative juridical methodology, this study draws on treaty law, state practice, and legal doctrine, while assessing pertinent international instruments such as the Paris Agreement, the United Nations Convention on the Law of the Sea (UNCLOS), and customary international law concerning transboundary environmental harm. The analysis indicates that, although the LoI is non-binding, it establishes a foundational platform for a legally enforceable bilateral treaty that may serve as a model for the region. Key legal challenges identified include jurisdictional clarity, liability allocation, environmental safeguards, and consistency with international climate obligations. The article concludes that the formulation of a robust bilateral agreement anchored in international legal norms is critical to ensuring legal certainty, environmental integrity, and reciprocal confidence in transboundary CCS implementation.