Although transboundary impact might be understood to include effects ranging from political and economic to ideological or intangible ones, in international environmental legal discourse the notion is generally understood to involve transboundary physical effects. Transboundary impacts in this former, wider sense may be subject to special treaty regimes, which, however, bear only indirectly on international environmental law. This article examines legal norms applicable to transboundary impacts on other individual states or group of states, their territory, natural resources, and people to the exclusion of transboundary effects of a global nature or affecting the global commons only. Much of international law governing transboundary impacts has an essentially bilateralist grounding. By contrast, norms applicable to the global commons more typically reflect the notion of an international communitarian interest in environmental protection. This article also considers transboundary environmental impacts in international law, international responsibility and liability for transboundary impacts, and the institutionalisation of transboundary environmental impact management.
