Marriage registration is a legal obligation aimed at ensuring marital status certainty and protecting children’s rights. In the indigenous community of Kampung Sereh, however, marriage validity is often determined by customary and religious legitimacy rather than state registration. This situation creates potential legal issues, including the status of children, inheritance rights, and population administration. The study seeks to analyze factors influencing legal compliance, identify obstacles, evaluate legal effectiveness, and develop a compliance model that respects local culture while guaranteeing legal certainty. Using a qualitative case study approach, the research applies Lawrence M. Friedman’s legal system theory, which emphasizes structure, substance, and culture. Data were obtained through observation and interviews with customary leaders, religious figures, village officials, and community members, and analyzed thematically. Findings reveal compliance is influenced by collaboration among officials, customary leaders, and the church; the alignment of rules with customary practice; and community perceptions of marital validity. Barriers include limited access, rigid procedures, timing differences between custom and state, and dominance of customary legitimacy. The study offers a Cultural-Legal Compliance Model integrating rituals with state registration through collaboration, local education, flexibility, and proportional incentives. Abstrak Pencatatan perkawinan merupakan kewajiban hukum yang dirancang untuk memastikan kepastian status pasangan dan perlindungan hak anak. Namun, di masyarakat adat Kampung Sereh, sahnya perkawinan lebih sering ditentukan oleh legitimasi adat dan agama daripada pencatatan negara. Kondisi ini berpotensi menimbulkan masalah hukum, seperti penetapan status anak, hak waris, dan administrasi kependudukan. Penelitian ini bertujuan menelaah faktor yang memengaruhi kepatuhan hukum, hambatan yang dihadapi, efektivitas hukum yang berlaku, sekaligus merumuskan model kepatuhan hukum yang menghargai budaya lokal namun tetap menjamin kepastian hukum. Penelitian dilakukan dengan pendekatan kualitatif dan desain studi kasus, berlandaskan teori sistem hukum Lawrence M. Friedman yang menekankan dimensi struktur, substansi, serta budaya hukum. Data diperoleh melalui observasi lapangan dan wawancara mendalam bersama tokoh adat, pemuka agama, aparat kampung, serta warga, kemudian dianalisis menggunakan teknik tematik. Hasil penelitian menunjukkan kepatuhan hukum dipengaruhi kolaborasi aparat kampung, tokoh adat, dan gereja; kesesuaian aturan formal dengan praktik adat; serta persepsi masyarakat mengenai sahnya perkawinan. Hambatan meliputi keterbatasan layanan, prosedur yang kaku, perbedaan waktu antara adat dan negara, serta dominasi legitimasi adat. Penelitian menawarkan Cultural-Legal Compliance Model yang memadukan prosesi adat dengan pencatatan negara melalui kolaborasi, edukasi lokal, fleksibilitas prosedural, serta penerapan insentif dan sanksi proporsional.