Child marriage is a serious human rights violation. The United Nations started tackling the issue in the 1990s. Nevertheless, Child marriage remains prevalent in certain regions, particularly in countries in sub-Saharan Africa. Previous research has shown that, despite passing a national law prohibiting child marriage in 2015, Chad, a country in sub-Saharan Africa, still has a high rate of child marriage. Therefore, this research aims to understand the reasons why the rate of child marriage in Chad remains at high level, even if the country passed a law in 2015. This research uses a qualitative approach, which is abductive reasoning, to assume the factors hindering policy intervention related to banning child marriage. The combination of desk study, secondary data analysis, and frame analysis are then used to discuss and analyse the institutional, socio-cultural, economic, and structural barriers to policy implementation. The finding exposited that the persistence of child marriage stems from weak governance, entrenched cultural norms, financial distress, and conflicting social, and structural attitudes. These factors undermine the effectiveness of legal interventions. This research employs social norms theory and policy implementation theory to explain why legal reforms fail in the absence of political, socio-cultural, and economic support systems. The research concludes that sustainable legal change in Chad related to child marriage requires a long-term, context-specific, multi-sectoral and economically supported approach. The research serves as a reference for failed policy interventions on child marriage in developing countries, highlighting the importance of aligning legal frameworks with social realities.