2. Traditional norms, principles, and rules

The fundamental norms and principles of international environmental law are embodied in customary law regarding the use of a state's territory. The principle of limited territorial sovereignty as expressed in the Roman law "maxim sic utere tuo ut alienum non laedas" means that states cannot use or permit the use of their territories to the detriment of the rights and legitimate interests of other states. This principle is intrinsically related to that of state responsibility: states are responsible for the damage that they cause to other states. The principle of limited territorial sovereignty has been invoked in the transfrontier pollution context by international tribunals, e.g., the Trail Smelter arbitration.² It was also incorporated in Principle 21 of the Stockholm Declaration on Human Environment:

States have, in accordance with the Charter of the United Nations and the principle of international law, the sovereign right to exploit their own resources pursuant to their own environmental policies, and the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction.³

The principle has also been codified into positive principles and rules in various treaty-making processes.

(A) Substantive principles and rules

Substantive principles and rules have been developed in the process of treaty-making on marine pollution, pollution of international rivers and lakes, atmospheric pollution, and the protection and conservation of fauna and flora. The international regulation of these problems has placed emphasis upon prevention rather than upon ex post facto remedies. Common legal techniques that are used include the identification of regulated activities and pollutants, the demarcation of the extent of jurisdiction, and the establishment of a regulating method, e.g., total prohibitions or restrictions on the production, trade, consumption, disposal, or emission of certain substances or pollutants, and standard-setting for those purposes.⁴

In contrast, principles and rules of state responsibility have not emerged in environmental treaty law. They are thought to be one of the problems that can be dealt with within the framework of general international law. However, certain treaties on marine pollution and nuclear hazards have established strict civil liability for the ship owner or the operator.⁵

(B) Procedural principles and rules

Procedural principles and rules have emerged simultaneous to the development of the substantive principles and rules. These procedural principles and rules, both customary and conventional, clarify and/or elaborate upon the procedural duties of due care or diligence of the states to protect the environment. They also supplement the implementation of the objectives of the substantive principles and rules. Examples include the principle of information exchange, the principle of environmental impact assessment, the principle of prior notification, the principle of warning, and the principle of consultation.⁶