This article addresses the question whether the Responsibility to Protect (RtoP) promotes a 'common humanity'. It observes how overt references to common humanity have receded from the RtoP discourse with the World Summit Outcome (WSO) in 2005. Nonetheless, the WSO prompted greater attention to crimes against humanity, which might conceivably strengthen a minimalist conception of humanity through the prosecution of its opposite number, inhumanity. This article tests Ruti Teitel's argument that 'humanity law' is reshaping the discourse of international politics by looking at the UN Security Council debates over RtoP in South Sudan. It concludes that the Council's failure to refer South Sudan to the International Criminal Court for crimes against humanity further weakens RtoP's potential to communicate a solidarist norm.