6 Transboundary Environmental Impact Assessment and Strategic Environmental Assessment

Strategic environmental assessment (SEA) has emerged as a response to the criticism that environmental impact assessment (EIA) often comes late in the planning process when economic benefits are well defined and by which time it is difficult to analyse the potential environmental impact rigorously. The discussion certainly includes considerations on SEA, but more specific attention is paid to the development of transboundary EIA in the context of the Mekong region. The chapter begins by identifying and evaluating the development of both mechanisms under international law, including important treaties, soft-law documents and case law. The primary questions discussed are: What is the status quo of international arrangements on both mechanisms? Is transboundary EIA a customary rule and thus binding under international law? What are the key issues regarding the two processes or mechanisms? Which pathway is better for the development of transboundary EIA and SEA in the Mekong region?Keywords: case law; customary rule; environmental impact assessment (EIA); international law; Mekong region; potential environmental impact; soft-law documents; Strategic environmental assessment (SEA); transboundary EIA