Abstract

Transboundary haze pollution remains a recurrent environmental and political challenge in Southeast Asia. This article analyzes how the Association of Southeast Asian Nations (ASEAN) has institutionalized cooperation to address this issue, highlighting its shift from fragmented to more structured but flexible governance. Drawing on an integrated framework that combines transaction cost economics, regime theory, and commons governance, the study traces ASEAN’s progression from low to medium institutionalization across four key milestones: the 1995 ASEAN Cooperation Plan, the 1997 Regional Haze Action Plan, the 2002 ASEAN Agreement on Transboundary Haze Pollution, and its subsequent implementation. Rather than interpreting ASEAN’s trajectory as institutional stagnation, it argues that ASEAN’s emphasis on consensus, informality, and non-interference reflects a strategic adaptation to regional interdependence, sovereignty sensitivities, and political diversity. The analysis demonstrates how medium institutionalization has enabled cooperation in a region where centralized enforcement is not feasible. By institutionalizing haze governance through a loosely coupled but resilient framework, ASEAN’s approach offers lessons for regions confronting transboundary environmental challenges and collective action dilemmas under sovereignty constraints.