Due Regard and Due Diligence

Abstract Chapter Four examines the practice in the same international courts as Chapter Three, this time focusing on ‘due regard’ and ‘due diligence’. These emerging regulatory standards require that States have due regard for one another’s rights and interests, and that States exercise due diligence in the control of activity that may cause transboundary harm. As in Chapter Three, the standards seen in these cases are often accommodating of domestic authority. Due diligence, particularly, significantly accommodates domestic authority. International legal obligations for States to control private conduct and prevent transboundary harm are understood only as obligations of conduct or limited due diligence obligations. This tends to leave international law less equipped to mandate the action from States that will better fulfil States’ combined substantive needs. The emerging global regulatory standards thus appear to do too little to enhance traditional substantive justifications for international law’s claim to legitimate authority.