The Standard of Proof Used by International Courts in Disputes Between States : An Analysis of the Approaches to Standards of Proof in the Attribution of State Responsibility by the ICJ and ITLOS

Sammanfattning

This thesis examines how the International Court of Justice (ICJ) and the International Tribunal for the Law of the Sea (ITLOS) approach the standard of proof, and how their respective institutional roles within the international legal framework shape that approach. The standard of proof plays a central role in international adjudication, as it determines whether the facts of a case have been sufficiently established to support a finding of state responsibility. Despite its significance, the articulation and application of evidentiary standards by international courts remain largely opaque. The thesis analyses the jurisprudence of the ICJ and ITLOS together with relevant scholarly writings in order to identify how each court formulates evidentiary thresholds, the factors influencing these formulations, and their implications. The analysis demonstrates that both courts apply a flexible standard of proof, tailored to the circumstances of each case. In cases involving allegations of a higher gravity, a higher evidentiary threshold is required. The formulation of the standard also varies depending on the function the court performs, including whether the case concerns deliberate acts or omissions. However, ITLOS has generally been less explicit in its engagement with evidentiary standards. This may be explained by ITLOS’s limited jurisprudence and its narrower jurisdiction. The thesis further shows that evidentiary approaches are influenced by broader considerations, including state consent, sovereignty, and the potential political consequences of judicial decisions. These considerations must be balanced against competing values such as legality, transparency, predictability, and judicial legitimacy. The thesis concludes that the standard of proof applied by both courts is significantly shaped by their institutional roles within the international legal framework. Both courts adopt a flexible approach while also being constrained by their function as international courts tasked with settling disputes between sovereign states and navigating the political ramifications of their judgments.