That large-scale industrial, agricultural, and technical activities conducted in the territory of one country can cause detrimental effects in the territory of another country or to areas of the global commons is by no means a novel problem in international law. Such transboundary damage has given rise to numerous theories of State responsibility or liability, focusing on remedial rules. But for a long time State practice in this field remained inconsistent and fragmentary. During the past two decades, however, the scope and content of the subject have dramatically expanded, exerting a direct impact on the codification and progressive development of international law in three important fields: (1) the regime of State responsibility; (2) international liability for injurious consequences arising from acts not prohibited by international law; and (3) international environmental law. State responsibility and international liability for injurious consequences have been two of the major issues on the agenda of the International Law Commission (ILC).

In current parlance, transboundary damage is also often referred to as environmental damage, but of a specific type, namely, environmental damage caused by or originating in one State, and affecting the territory of another. There is a vast body of international treaties on various forms of transboundary damage – pollution of international waters, long-range air pollution, land-source damage to the ocean and oil pollution, to give only a few examples.