A 'Missed' Secondary Rule? Causation in the Breach of Preventive and Due Diligence Obligations

This contribution addresses the role of causation in the establishment of wrongfulness. While the International Law Commission (ILC) Articles on the Responsibility of States for Internationally Wrongful Acts place causality outside the conditions for an international wrongful act to accrue and treat it as an question pertaining to the interpretation and application of primary rules, this chapter argues that causality is a missed “secondary” element for assessing the breach of certain categories of international obligations. Specifically, causal queries come in to play whenever adjudicators need to evaluate the extent of a state’s responsibility for failing to comply with preventive and other due diligence obligations. Moving from a critical reassessment of the ILC approach to breaches of preventive obligations, this chapter grasps at the normative function performed by causality in tailoring the scope of states’ due diligence obligations and illustrates the hurdles of the causal question in this context.