Customary international law contains few rules directly relevant to the control of marine pollution. Two cases are sometimes cited to illustrate the existence of such rules. In the Corfu Channel Case (1949), we find the much quoted statement by the International Court of Justice to the effect that each state is under an obligation not to knowingly allow its territory to be used for acts contrary of the rights of other states. In the Trail Smelter Arbitration (1938–41), an even earlier case involving damage to property in the United States (US) caused by noxious fumes emitted by a smelter in Canada, the arbitral tribunal held that no state has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another state.
It is difficult, however, to adduce any particular standards regarding the control of maritime pollution from these two cases, let alone find in them sufficient evidence of the necessary opinio juris and state practice required for establishing settled rules of customary international law. The Corfu Channel Case was not, as such, concerned with pollution damage but with other types of harm resulting from the unauthorised mining of the channel. In addition, the statements issued by the court and the tribunal respectively centred on the use of territory by states and they cannot be taken as establishing general principles of law applicable to acts beyond the territorial boundaries of a state. Accordingly, it is to the United Nations Law of the Sea Convention (LOSC) and other treaties that we must look to establish the legal basis for control of pollution.