Informal authorities in European private law

Abstract

Th is article considers the nature of authorities in the law, and, specifi cally, the oft en undervalued yet important role played by informal auctoritas, in contrast to formally binding enactments. It explores the terminological diffi culties within modern discourse which make discussion and understanding of such informal authorities diffi cult. Exemplarily, the status of Roman sources in the ius commune is considered in detail, establishing the informal criteria which determine their authoritative quality – belief in the extraordinary quality of the texts and the jurists’ mutual expectations of applying them. Th e analysis then proceeds to modern German practice and the enormously signifi cant role played by learned commentaries in the work of practising lawyers and courts – a phenomenon diffi cult to explain without recourse to a concept of informal authority. Finally, this understanding is demonstrated in the context of transnational private law by reference to the modern phenomenon of non-legislative codifi cations, such as the American Restatements, the Principles of European Contract Law and the UNIDROIT Principles of International Commercial Contracts: all those codifi cations have gained substantial informal authority as reference texts for international legal discourse.