<![CDATA[This study examines isbat nikah (marriage legalization) as a legal alternative for unregistered underage marriages in Indonesia, focusing on the Ujung Tanjung Religious Court in Rokan Hilir Regency, Riau Province. The persistent rise in isbat nikah petitions—47,344 in 2020, 46,942 in 2021, and 58,017 in 2022—reflects the structural gap between Indonesia's formal prohibition of child marriage under Law Number 16 of 2019 and the social reality of widespread, unregistered underage unions. This study applies a qualitative, empirical-juridical field research design, combining court observations, interviews with judges and registrars, and documentary analysis. Three objectives are addressed: (1) the meaning and function of isbat nikah as a legal alternative for underage marriages; (2) the regulatory framework governing isbat nikah in Indonesia; and (3) Islamic law perspectives on minimum marriage ages across Muslim-majority countries. Findings show that judges at the Ujung Tanjung Religious Court apply a substantive-over-formal approach, prioritising the fulfilment of Islamic marriage pillars over formal age compliance. Grounded in maslahah mursalah under Article 7 of the Compilation of Islamic Law, isbat nikah provides indispensable legal recognition for couples and the children of unregistered unions. Comparative analysis reveals wide variation in minimum marriage ages across Muslim countries, shaped by fiqh school traditions, colonial legal histories, and reform trajectories. Analysis through maqasid al-shariah identifies a fundamental tension: while isbat nikah protects preservation of lineage, religion, and property, child marriage violates the objectives of preserving life, intellect, and physical wellbeing. The study concludes that isbat nikah must be retained as a remedial legal instrument while stronger preventive policies are urgently needed to curtail the normalisation of child marriage.]]>
