The Breach of the Obligation to Prevent Environmental Harm and the Law of State Responsibility

International environmental law is rightly perceived as one of the most challenging fields for the secondary rules governing State responsibility. In particular, the conditions for establishing how the critical obligation of States to prevent environmental harm has been breached remain rather obscure. The Articles on the Responsibility of States for Internationally Wrongful Acts, adopted by the UN ILC in 2001, do not help to clarify the issue of whether preventive commitments of States in the field of environmental protection can be classified as obligations of conduct, of result, or otherwise. Considering the poor conceptualization of the matter in the ILC Articles, very little can be expected from the test of judicial application to which the same Articles are currently submitted. Nonetheless, recent international case law in environmental matters reveals that international judges are inclined to rest on the qualification of the States’ obligations to prevent environmental harm as one of conduct or of due diligence and to elaborate about the conditions governing the breach of such obligation. The present contribution aims at revisiting the issue of the breach of the obligation to prevent environmental damage in light of recent international case law and to assess its relevance for the process of the codification of State responsibility.