Abstract
Marriage, as a fundamental institution, plays an important role in determining civil rights and the legal status of citizens; therefore, its regulation reflects social, cultural, and religious values, as well as human rights principles. This study aims to compare the legal regulation of same-sex marriage in Thailand by examining the absence of legal recognition of same-sex marriage in Indonesia and assessing how social and cultural realities influence the acceptance and effectiveness of law in both countries. This research employs a normative juridical method, using statutory and conceptual approaches, by examining Law Number 1 of 1974 and Constitutional Court decisions in Indonesia, as well as the Marriage Equality Act 2025 and the Civil and Commercial Code in Thailand. The findings show that Indonesia explicitly limits marriage to heterosexual relationships based on the first principle of Pancasila, namely “Belief in the One and Only God”, thereby providing no legal recognition or civil rights for same-sex couples, including inheritance rights, marital property rights, and administrative protection. In contrast, Thailand provides full legal recognition of same-sex marriage through progressive legal reform, guaranteeing equal rights in civil registration, inheritance, social security, and adoption, although challenges in administrative implementation remain. Comparatively, the effectiveness of same-sex marriage regulation is strongly influenced by the level of social acceptance: Indonesia is shaped by Pancasila, which emphasizes morality, religion, and culture, whereas Thailand demonstrates that social openness is a key factor in the successful implementation of legal reform.