This book seeks to analyse various aspects of international law, the link being how they structure and marshal the different forces in the international legal order. It takes the following approaches to the matter. First, an attempt is made to determine the fundamental characteristics of international law, the forces that delineate and permeate its applications. Secondly, the multiple relations between law and policy are analysed. Politics are a highly relevant factor in the implementation of every legal order (and also a threat to it); this is all the more true in international law, where the two forces, law and politics, have significant links. Thirdly, the discussion focuses on a series of fundamental socio-legal notions: the common good, justice, legal security, reciprocity (plus equality and proportionality), liberty, ethics and social morality, and reason.