Diplomatic representation in the community of the European diplomacy of the ‘Trente heureuses’ (1713–1740). – The study of Ancien Regime public international law compels researchers to broaden the traditional scope of legal history (treaties and doctrine). A broader understanding of normativity in international relations, inspired by sociology, cultural or international relations history leads to an analysis of diplomatic behaviour. Practice is of paramount importance to grasp the working of implicit principles, expressed in correspondence and legal memoranda. The three decades following the Peace of Utrecht (1713) illustrate how state consent-based international organisation operated in the 18th century, separate from doctrinal concepts. French and British archival material and existing prosopographic literature sketch a map of the European arena. Treaty interpretation and legal reasoning were the backbone of international relations. Consequently, jurists were more than apologists, and fulfilled an indispensable role in an interactional system.