The maritime transport of dangerous goods (DG), including hazardous and noxious substances (HNS), poses
escalating environmental and legal challenges, particularly in Southeast Asia’s high-traffic corridors. While
international frameworks such as UNCLOS, MARPOL, and the IMDG code impose clear obligations, ASEAN
member states exhibit fragmented implementation and limited HNS-specific preparedness. This paper critically assesses the region’s regulatory landscape through a legal-doctrinal and theoretical lens, identifying gaps
in treaty ratification, port state control, and regional cooperation. It argues that soft-law mechanisms and institutional inertia undermine effective risk governance. This study calls for a binding regional instrument on
HNS response, harmonized inspection regimes, and integrated liability frameworks to align ASEAN practices
with global marine protection standards. Accordingly, the purpose of this work is to examine how ASEAN’s
approach to DG transport aligns with international maritime law and to propose reforms that strengthen both
regional and global marine environmental governance.