“…Moreover, biguous terms by Article IV of the US-Mexico Agreeclassic exonerations of the acts, force majeure or acts of ment, 44 which provides that 'the country of export shall God or intervening acts of their persons are frequently readmit any shipment of hazardous waste that may be excluded'. 40 Even the defences of due diligence or lack returned for any reason by the country of import' of knowledge, which are available to states with respect (emphasis added). The work of the Ad Hoc Working Group is a welcome rests with the state whose conduct caused the shipment initiative.…”