ABSTRACT
The early and rather tentative case law under customary international law had concentrated upon the duty of one state not to knowingly allow activities upon its territory to damage the territory or interests of another state.81 However, from this general proposition can be deduced a duty to notify other states of environmental harm. Thus, Principle 18 of the Rio Declaration (1992) provides that ‘States shall immediately inform other States of any natural disasters or other emergencies that are likely to produce sudden harmful effects on the environment’.82 This is supplemented by Principle 19, which provides that ‘States shall provide prior and timely notification and relevant information to potentially affected States on activities that may have a significant adverse transboundary effect and shall consult with those States at an early stage and in good faith’.
