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Expert Rule? Judges, Lawyers, and the Practices of Interpretation in International Criminal Law

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How do international courts develop international criminal law?

The number of international courts has increased significantly over the past three decades and international judges have begun to develop law through their decisions, especially in international criminal law. How were international criminal courts able to develop law so substantially, and with what consequences?


International judges have been updating or clarifying the legal meaning of specific provisions. In international criminal law, a particularly prominent example, international judges repeatedly describe the development of law as one of their main achievements. How far do judicial interpretations matter in global governance? How were international courts, required to remain within the boundaries of existing law, able to develop law so substantially, and with what consequences? The EU-funded EaRL project addressed these questions by looking into the broader relevance of the decisions rendered by international criminal courts as they’ve faced increasing pressure. “I examined three reasons for judicial discretion articulated in legal theory: possible ‘gaps’ within legal provisions as unforeseen circumstances arise; types of legal provisions that provide more room for discretion such as customary law; and the process of legal reasoning in which legal provisions are applied to factual situations that are themselves often inconclusive,” says Nora Stappert, Marie Skłodowska-Curie fellow. Legal theory is reflected in the professional convictions lawyers hold about how to interpret international law. According to Stappert: “In international criminal law, one of the assumptions widespread among judges and legal officers was that international courts should be careful not to overstep their responsibilities, which as a result curbed the potential for creativity and change in legal interpretation.”

International Criminal Court established

Since the end of the Cold War, the number of international courts has increased considerably. One example is the international criminal tribunals established by the UN Security Council in the early 1990s to focus on Rwanda and the former Yugoslavia. This led to the 1998 treaty establishing the International Criminal Court (ICC) as the first permanent international court to hold individuals accountable for genocide, war crimes, and crimes against humanity. International criminal courts started to produce a growing body of case law whose decisions not only addressed case facts, but untangled difficult legal questions. Consequently, they decided how the questions apply to the case at hand (e.g. how to interpret the law of command responsibility, a form of liability that holds military commanders responsible for offences committed by their subordinates).

Developing international criminal law

When addressing legal questions, international courts may develop international law. In many legal systems, judges develop law as they specify a rule’s meaning when applying it to a new case, which can become a precedent referred to in future decisions. The difference is that in international criminal law, international courts have developed law particularly rapidly. The EaRL project used legal theory and social research methods to understand how such developments are possible despite a strong requirement to root legal interpretations in existing law. Examining how international courts function is important as several international courts have come under increasing pressure. The ICC faced accusations of bias against Africans, and some states threatened and withdrew from the court. In December 2019, an Independent Expert Review was formally established to improve the work of the court. Stappert’s investigations yielded important results that explored how the practices of legal interpretation can develop legal meaning along with a methodological toolbox for studying the practices of legal interpretation in international law empirically.


EaRL, international courts, international criminal law, judicial interpretations, global governance

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