International law claims to be the most universal field of law: one law for all sovereign nations of the world. This article is discussing some issues of this process of universalization of international law in the 19th century: Which were the achievements of ›one law for all‹ in international law, with which methodological premises did it go along and what were its alternatives? Which excluding aspects did international law bear at that time? Which particularizations and discriminations did the doctrine incorporate and to what extent can a cultural history of law contribute to its analysis? And finally: Why shall we go beyond legal pluralism? Obviously there is a historiographical challenge and I would like to plea for a wider scope of normativity when analyzing the multiple entangled ways of pre-modern normative orders addressing the interstate relations (Ius Gentium, natural law, moral philosophy) to modern global legal regimes (international law). With the idea of “multinormativity” one could analyze the interweavement, transfer and hybridization of norms from different spheres. The international law doctrine of the 19th century represented in this perspective a distinct social order with many ambivalences. It was never a pure “positivist” legal regime. The social, philosophical and political contexts of legal thinking and legal practice were directly affecting the entangled problems of universalization, equality and structural discrimination in 19th century international legal doctrine.