The International Court of Justice and the world's three legal systems

This paper seeks to understand why some countries accept the jurisdiction of the International Court of Justice (ICJ) more readily than others. The theory focuses on institutional differences between the world's major legal systems: civil law, common law, and Islamic law. Important characteristics of these legal systems (stare decisis, bona fides, pacta sunt servanda) are integrated in an expressive theory of adjudication, which focuses on how adjudication enhances interstate cooperation by correlating strategies, constructing focal points, and signaling information. The theory considers the ability of states to communicate with each other, using acceptance of ICJ jurisdiction as a form of cheap talk. Empirical analyses show (1) civil law states are more likely to accept the jurisdiction of the ICJ than common law or Islamic law states, (2) common law states place the greatest number of restrictions on their ICJ commitments, and (3) Islamic law states have the most durable commitments.