Judicial Legislation, Not Lawmaking: How the ICJ Fills Legal Gaps Without Creating New Law

The International Court of Justice (ICJ) often faces criticism for allegedly exceeding its mandateby engaging in what some perceive as lawmaking. This debate, though not new, continues tospark significant scholarly discourse and is even echoed by some of its own judges. Althoughthe ICJ consistently denies having a lawmaking function, its practices demonstrate its role in thedevelopment of international law. This raises the question: How can the Court contribute to thedevelopment of international law, particularly in addressing gaps, if it lacks formal lawmakingcapacities? Are the criticisms of the Court exceeding its mandate valid? Existing literatureoften conflates ‘judicial legislation’ with ‘lawmaking’, creating a bottleneck in reasoning whichcausing scholars to necessarily conclude that the ICJ inevitably exceeds its judiciary mandate andengages in creating new laws. However, understanding the ICJ’s role in developing internationallaw and addressing gaps, despite its statutory limitations, requires distinguishing between‘judicial legislation’ and ‘lawmaking’. While the latter involves creating new laws, ‘judiciallegislation’ refers to a method of interpretation for adapting existing laws and establishing newlegal relationships to address emerging legal requirements. This article goes further to identifywhich types of interpretation are most effective for such judicial legislation. By examining theapproaches of the UN International Law Commission (ILC), the article highlights ‘evolutiveinterpretation’ as a particularly suitable method. Evolutive interpretation enables the Court torejuvenate existing laws, clarify ambiguities, and develop legal frameworks for unregulatedissues – all while staying within its adjudicative-only mandate and avoiding lawmaking.