Introduction

This chapter highlights aspects of the process of diffusion of law as derived from the law and practice of the International Court of Justice (ICJ), the principal judicial organ of the United Nations seated at The Hague in The Netherlands. The ICJ is the world's only court having general jurisdiction over disputes between sovereign States. Diffusion of law is inherent in the concept of transnational law, which likewise is informed by interaction between legal systems and legal traditions. As understood here, legal diffusion essentially is a transnational phenomenon. This chapter seeks to increase our understanding of this phenomenon by focusing on the ICJ. Our focus on the ICJ in illustrating how legal diffusion occurs on the international plane comports with the goal to give ‘increased attention to public international law and institutions’ advocated by the casebook on Transnational Legal Problems for which Detlev Vagts has served as primary author/editor. According to that seminal work, the domain of transnational law is formed by international law and institutions together with aspects of national legal systems concerning ‘matters foreign’. As such, these constituent elements form ‘the legal framework bearing on relationships among nations or among their citizens and business entities’. Nations, citizens and businesses are all affected by the ICJ's work and they play various roles in it, as described below.