This thesis analyses the evolution of the sexual and gender-based violence prohibition norm at the International Criminal Court. Underpinned by social constructivist research on international norms, insights into the appropriate application of legal norms, as well as feminist institutionalist and legal perspectives, the evolution is identified as an outcome of a socialization process with the norm’s appropriate application. The case study, based on qualitative data analysis, embraces seven stages of this process, each accompanied by a triangulation inquiry. Connecting research on the evolution of norms in international relations with that on resistance practices against international courts, this analysis studies the constellation and agency of the involved actors, institutional and structural as well as socio-political factors. The findings of this study should contribute to the understanding and conceptualization of the evolution of international norms, specifically in the fields of human rights and gender justice from an interdisciplinary perspective, joining political, social and legal aspects through a feminist lens.