Reassessing the Allocation of Responsibilities in Global Marine Plastic Pollution : A Renewed Examination of the Principle of Common but Differentiated Responsibilities

Abstract

Marine plastic pollution is a transboundary challenge requiring urgent global cooperation. Such cooperation must rest on a unified framework that distributes responsibilities fairly and authoritatively while respecting national sovereignty. The Fifth United Nations Environment Assembly launched an intergovernmental negotiating committee to achieve a legally binding “Global Plastics Treaty” by 2024, yet the agreement remains elusive by the fifth session in 2025. Disputes persist over plastic source control, financing mechanisms, and raw material regulation—issues tied directly to allocating national responsibilities. This paper applies the principle of common but differentiated responsibilities (CBDR) to global marine plastic. It first clarifies the doctrinal foundations of CBDR and demonstrates its relevance for structuring responsibilities. It then analyses controversies and practices across national, regional, and multilateral levels, situating CBDR within ongoing treaty negotiations. The study further identifies challenges in applying CBDR, including instrumentalisation, contradictions in differentiation, outdated categories, interpretive conflicts, and deadlock over means of implementation. Building on this analysis, the paper advances policy strategies to operationalise CBDR. These include reforming procedural rules, constructing a dynamic and tiered responsibility system, designing a “core and flexible” obligations framework, and establishing multidimensional support and oversight. Together, these measures can transform CBDR from a source of division into a tool that reconciles diverse national interests and capacities. These proposals can pave the way toward an effective and universal plastics treaty that promotes ocean sustainability, global equity, and public health by enabling fair responsibility-sharing.