The liberal political thought has shaped views on normativity in international law by insisting on rule neutrality and determinacy through the sources doctrine and the idea of a clear-cut normative threshold. The present debate over the normative quality of diplomatic assurances poses an extraordinary challenge to these ideals. Moreover, any attempt to qualify the assurances as soft law further illustrates the manipulation of normativity-talk through the narratives of normative expansion and communitarisation. Ultimately, the liberal project cannot fulfill its promises, leaving international lawyers disenchanted.