Burden and Standard of Proof in International Courts: a Call for Greater Clarity and Consistency

This paper examines the burden and standard of proof in international courts and tribunals, particularly the International Court of Justice, noting a historical emphasis on law over facts and the adoption of a flexible approach to evidence. While the burden allocates the duty to prove, the standard defines the required evidentiary level and is complicated by civil-common law differences leading to varied ICJ application. Given the ICJ ’s increasingly fact-heavy jurisprudence, the paper argues for a clearer formulation of burden-of-proof rules emphasizing certainty, underpinned by the presumption of state compliance. It advocates for distinguishing between formulation (certainty) and application (flexibility using tools like presumptions for fairness). Promoting predictability and consistency is crucial for the legitimacy of international adjudication.