Annulment of Marriage Due to Religious Differences and Unauthorised Polygamy (A Study of Supreme Court Decision No. 435 K/Ag/2026)

A subsequent marriage contracted while an earlier marriage remains legally subsisting, without judicial authorisation for polygamy, raises questions about capacity, validity and annulment, particularly when the parties also profess different religions. This article examines the doctrinal relationship between religious validity, the statutory impediment to remarriage and judicial annulment, with Supreme Court Decision No. 435 K/Ag/2026 as its reported case context. It adopts normative legal research using statutory, conceptual and case approaches. The analysis finds that religious differences under Article 2(1) of the Marriage Law and unauthorised polygamy under Articles 3–5 and 9 concern legally distinct questions. The absence of the required authorisation, alongside a subsisting earlier marriage, may support an annulment claim under Articles 22 and 24, independently of the broader debate over interfaith marriages. A decree must nevertheless safeguard children and the interests protected from retroactive effects under Article 28. The article proposes a three-stage reasoning framework addressing validity, the proven annulment ground and legal consequences. The full judicial reasoning still requires checking against the authenticated decision before case-specific conclusions are finalised.