This investigation paper attempts to perform a positivist approach to the unity and coherence of international law, based on a documental scrutiny of the conceptions of Hans Kelsen and Herbert Hart on these two properties of law applied to the international normative system. Likewise, this paper characterizes the development of international law as fragmented, that is, created from regimes closed by the cognitive content regulated in them, a situation which makes it susceptible to the presence of conflicts between norms, which, precisely, could be avoided in a sufficiently unitary and coherent law.