Investigating the effectiveness of strategic environmental assessment in Thailand

Strategic environmental assessment (SEA) was introduced in Thailand in 2005, aiming to direct decision-making at the strategic level (policy, programme, plan) towards sustainable development. Given reforms to the SEA requirements in 2018, it is timely to evaluate emerging SEA experience in the Thai context to inform future practice. The effectiveness of 14 SEAs was investigated based on a version of a recently published framework which substitutes 'legitimacy' for normative effectiveness and pluralism, modified through the addition of disaggregated sub-criteria associated with each dimension of effectiveness (procedural, substantive, transactive, and legitimacy), to facilitate a richer understanding of the effectiveness of practice. This more detailed effectiveness framework enabled a comprehensive evaluation of practice, and should be transferable to other contexts. The findings suggest that SEA in Thailand currently partially achieves procedural, substantive, and transactive effectiveness. Achieving some elements of substantive effectiveness where practice is currently weak is considered to be particularly challenging, and also determinative in the achievement of legitimacy. Consequently, the majority of SEAs evaluated in this study failed to achieve legitimacy.