5. Material changes in the law of state responsibility

Three levels of state responsibility have been identified in relation to the environment: the mildest and most traditional one is that related to responsibility on the basis of fault or lack of due diligence; an intermediate level, called objective or strict responsibility, is related to an obligation of result, which is the obligation not to damage the environment and the violation of which will engage responsibility regardless of fault; the most stringent level, referred to as absolute responsibility, concerns liability for acts not prohibited by international law irrespective of fault or of the lawfulness of the activity in question.³⁴

Examples of all these types of responsibility can be found in contemporary international environmental law. The Law of the Sea Convention regime is mostly based on the due diligence test,³⁵ an obligation of result involving objective or strict liability is found in the Convention on Environmental Modification Techniques,³⁶ and finally, absolute international liability is found in the Convention on International Liability for Damage Caused by Space Objects.³⁷ Most treaties rely on general obligations of cooperation or the commitment to take appropriate measures to prevent pollution, and thus involve only a due diligence obligation to prevent pollution, the mildest of the three standards.

However, the fact that international law has been exploring more stringent forms of responsibility is, in and of itself, indicative of the sense of change that is taking place.³⁸ The most significant of these changes is the introduction of the concept of absolute and strict liability. Delinking the adverse effects of a given hazardous or dangerous activity from the element of culpa of the state or operator incorporates the test of "objective" responsibility as opposed to the "subjective" criteria of traditional international law.³⁹ Still more stringent criteria have been emerging lately, particularly as concerns the idea of holding a state responsible for damage ensuing from given activities irrespective of whether it took all necessary measures to prevent injury. The result is that responsibility will attach in spite of due diligence having been observed. Liability for acts not prohibited by international law is another major development that will be examined in more detail below.

The issue of environmental damage has also given rise to interesting developments in the international law of responsibility. First, in addition to traditional notions of economic damage, international law is beginning to recognize environmental damage as such for the purpose of invoking the responsibility of states.⁴⁰ In this context the environment becomes a value on its own merits and is protected by the law, as evidenced by Cosmos 954,⁴¹ the recent Patmos Case,⁴² and, above all, by the Antarctic arrangements.⁴³

Second, the International Law Commission has made the point that material damage would not be an essential element in the case of responsibility for wrongful acts. The attribution of the conduct to the state and the breach of an international obligation would suffice to invoke responsibility.⁴⁴ Under traditional international law, however, the violation of the obligation would be sufficient to engage responsibility, which means that the old rules are very helpful indeed to broaden the scope of the law at present. On the other hand, when the international liability is for acts not prohibited by international law, material damage would be the essential basis of compensation,⁴⁵ resulting in the paradox that, on this point, the new rules are more restrictive than the old.

Although the seriousness of the damage is another issue where the practice is not entirely uniform, certain gravity is, without a doubt, required. This requirement, however, is qualified by two considerations that relate to the evolving state of international law. First, given the emphasis on preventive measures characterizing present environmental law, the adoption of all necessary preventive and remedial measures even where no injury has occurred is beginning to emerge as a new type of obligation. Second, as mentioned in the Restatement of the Law (Third), when pollution is caused by substances that are highly dangerous to human life and health, there is no need to prove a significant impact or injury, thereby altering rather dramatically the traditional standards of international law.⁴⁶ Examples of this trend are blacklisting of hazardous products and abnormally dangerous activities like the launching of space objects.⁴⁷