<![CDATA[This study aims to analyze the legal implications of the relationship between children born out of wedlock and their biological fathers, particularly in relation to inheritance rights following Constitutional Court Decision Number 46/PUU-VIII/2010. The research addresses the normative tension between civil law recognition of paternity and the concept of lineage (nasab) within Indonesia’s plural legal system. Using a normative juridical method with statutory, conceptual, and comparative approaches, this study examines legal materials and judicial practices. The findings indicate that while the Constitutional Court decision expands civil recognition based on biological proof, it does not fully harmonize with inheritance regimes, especially within Islamic law, resulting in legal uncertainty, inconsistent judicial interpretation, and administrative barriers in inheritance processes. Therefore, the effectiveness of legal protection for children born out of wedlock depends on regulatory harmonization and consistent legal interpretation. The novelty of this study lies in its systematic analysis of the unresolved normative conflict between civil relationship and lineage concepts and its practical implications for inheritance law, offering a conceptual framework for legal harmonization to ensure certainty and justice. Penelitian ini bertujuan untuk menganalisis implikasi yuridis hubungan hukum anak luar kawin dengan ayah biologisnya, khususnya terkait hak waris pasca Putusan Mahkamah Konstitusi Nomor 46/PUU-VIII/2010. Penelitian ini berangkat dari adanya ketegangan normatif antara pengakuan hubungan keperdataan dan konsep nasab dalam sistem hukum Indonesia yang pluralistik. Metode yang digunakan adalah yuridis normatif dengan pendekatan perundang-undangan, konseptual, dan komparatif. Hasil penelitian menunjukkan bahwa putusan tersebut memperluas pengakuan hubungan keperdataan berbasis pembuktian biologis, namun belum sepenuhnya terharmonisasi dengan sistem kewarisan, khususnya dalam hukum Islam, sehingga menimbulkan ketidakpastian hukum, inkonsistensi putusan hakim, serta hambatan administratif dalam praktik kewarisan. Oleh karena itu, diperlukan harmonisasi regulasi dan keseragaman penafsiran hukum. Kebaruan penelitian ini terletak pada analisis sistematis terhadap konflik normatif antara hubungan keperdataan dan nasab serta implikasi praktisnya dalam hukum kewarisan, yang menghasilkan kerangka konseptual untuk mewujudkan kepastian dan keadilan hukum.]]>
