States tend to comply with international law, but what happens if a State breaks a rule of international law? ‘Implementing international law’ considers the different ways in which international law is implemented—diplomatic protest through acts of retorsion, counter-measures, litigation, arbitration, and mediation. If litigation is necessary, most cases in which international law is applied arise in municipal courts and tribunals. Only a small proportion of cases that are decided by the application of rules of international law are taken to the International Court. Despite the increasing engagement between international law and individuals, the particular focus of international law remains fixed upon States and State responsibility.