The significant link between human rights violations and the eventual outbreak of atrocity crimes has been widely promoted across the UN system. However, the question of how the connection between the R2P norm and human rights plays out in the actual practices and debates of the UN Security Council has been relatively under explored. In response, the article builds on constructivist research into norm robustness in order to trace how the R2P's shift to an atrocity prevention focus has generated increased applicatory contestation over the push to expand the link between human rights and threats to international peace and security. Based on extensive analysis of UN Security Council meeting records and three case studies, the article highlights two competing ideological frames that currently divide the Security Council's approach to atrocity prevention. This division has emphasised a key disconnect between the work of the Security Council and other UN institutions such as the Human Rights Council, therefore severely limiting the potential for effective atrocity prevention responses. Thus, without a stronger connection to human rights in the process of threat identification, the R2P norm will remain considerably limited as a prevention tool. Consequently, the article also contributes to a new understanding of the critical role evolving institutional rules and practices play in state attempts to both constrain and reshape human protection norms.