ironmental law has developed in a mostly sectoral and ad hoc manner. Regimes have been devised to address specific global or regional environmental problems, such as particular sources and types of transboundary pollution, rather than to promote transboundary environmental governance in a holistic and integrated manner.1 As a consequence there is today an array of international environmental regimes but a lack of coordination among them, and many regimes operate independently, and sometimes even inconsistently, in relation to each another.