Unwritten European rules in international law: From Eurocentric to regional international law?

Treaties are the most visible, some would even say the ‘main source of international law’. This is true not only at the global level, but even more so in Europe. However, these treaties hardly explain the idiosyncratic, sometimes exceptionalist ways in which international law is identified, interpreted, and applied in this region. Still less do they explain the disproportionate normative influence of European legal rules outside Europe. Attributing these particularities and imbalances to ‘eurocentrism’ in international law is considered almost a truism these days. Yet, when examining how the European legal tradition translates into positive international law one category of rules has received little attention so far: the unwritten European rules that are resorted to within and beyond Europe. The idea of ‘unwritten’ European rules is not only historically charged but also conceptually vague. However, this article argues that a close analysis of their role is central to both understanding and overcoming the persistence of ‘eurocentrism’ in international law. To demonstrate this claim, the article introduces the term ‘unwritten’ European rules in international law. A historical section illustrates their ambivalent role since the beginning of the nineteenth century. It then analyses the continuing relevance of unwritten European rules in contemporary legal practice. The final section discusses how a common framework of secondary rules can help to distinguish between hegemonic and integrative uses of unwritten European rules, before concluding.