Increased appreciation of the many risks to the earth’s environment and the potentially irreversible damage which may be caused by human activity has resulted in a conscious effort by governments acting collectively, by international organizations, and by non-governmental organizations, to enhance legal protection of the environ-ment.¹ The resulting agenda is extensive: it includes the depletion of the ozone layer, problems of transboundary air pollution and anthropogenic climate change, the risks created by reliance upon nuclear power, the protection of the polar regions, the conservation of endangered species of flora and fauna, the control of the disposal of ultrahazardous wastes, and a range of procedural obligations from information exchange to environmental assessment. The policy issues generated by such an agenda are oft en difficult to resolve: inevitably the issues do not concern the ‘environment’ in isolation, but relate to economic and social priorities, systems of loss distribution and issues of development. Reconciling the protection of the environment with other issues such as these is sometimes referred to as the goal of sustainable development.

(p. 353) (A)  Environmental Issues under General International Law

Environmental concerns are reflected in many areas of international law: relevant categories include the law of the sea, the legal regime of Antarctica, and the non-navigational uses of international watercourses. Simultaneously, it is evident that general international law does not provide the focused problem-solving which results from carefully prepared standard-setting treaties linked with domestic and international support systems and funding. The development of specialized environmental regimes by treaty serves to address this deficiency.

Nonetheless, the legal underpinnings of the protection of the environment continue to be institutions of general international law. This is apparent from the literature, which typically invokes the principles of state responsibility of the territorial sovereign for sources of danger to other states created or tolerated within its territory, and cites Trail Smelter² and (less appropriately) Corfu Channel.³ It comes as no surprise that cases concerning environmental issues have also—and centrally—involved issues of general international law. Nuclear Tests concerned issues of admissibility and remedial law, as well as the status of unilateral promises.⁴Certain Phosphate Lands in Nauru related to issues of admissibility, the regime of a former UN trust territory, and state responsibility.⁵ The advisory opinion of the ITLOS Seabed Disputes Chamber, on responsibility and liability for international seabed mining, addressed important questions of treaty interpretation.⁶

In practice, specific transboundary problems will have a background in treaty relations and other dealings between states. Gabčíkovo-Nagymaros, relating to a joint hydroelectric project on the Danube, was concerned with the law of treaties and related points of state responsibility (issues of justification for alleged breaches of treaty obligations).⁷ Pulp Mills dealt with the law of treaties, international organizations, and international watercourses.⁸ Environmental concerns may arise in connection with law of the sea issues,⁹ and international trade disputes brought before the WTO Dispute Settlement Body,¹⁰ among others.

References(p. 354) (B)  Deficiencies in the Adversarial System of Responsibility

The key problem with focusing on responsibility as a means of ensuring environmental protection is that it addresses issues after damage has already occurred, instead of focusing on the need for prevention of damage in the first place. This deficiency is reflected in the growing support for the principle of preventive action in the area of environmental protection.

A particular difficulty is the selection and deployment of an appropriate basis of claim. Environmental impacts are often, in physical terms, incremental and may involve complex and diffuse causal mechanisms. The requirement of material or significant damage as a necessary condition of claim bears an uneasy relation to the scientific proof of a certain threshold of damage caused by an overall rise in radiation or other forms of pollution, and problems of multiple causation oft en arise.

In Nuclear Tests, the applicants employed the international law equivalent of trespass to deal with this problem: the deposit of radioactive fall-out was classified as a violation of their territorial sovereignty.¹¹ Likewise, the concept of ‘decisional sovereignty’ was used, referring to their right to determine what acts should take place within its territory. Implicit in these arguments was the proposition that little or no material harm to the applicants or their nationals would be caused by levels of fall-out which—over the distances involved—were rather less than the natural background radiation. The Court in a somewhat contrived manner avoided the problem, and French atmospheric testing ceased.¹²

It has been said that the decision in Nuclear Tests ‘suggested that an international tribunal cannot grant injunctions or prohibitory orders restraining violations of international law’.¹³ This is unjustified, and declarations are given by the Court which are injunctive in effect, as the joint dissenting opinion pointed out.¹⁴

But international claims—whether before the Court or a tribunal—can take many years to resolve, during which time the project in question—whether dam,¹⁵ bridge,¹⁶ orReferences(p. 355) large-scale land reclamation project¹⁷—may have been completed with little prospect of reversal. Requests for interim measures of protection addressed to the International Court or other tribunals thus have a crucial role.¹⁸

(C)  The Rio Conference 1992 and the Development of International Environmental Law

Evidence of international concern for environmental protection may be found in earlier international agreements¹⁹ such as the Convention relative to the Preservation of Fauna and Flora in their Natural Habitat (1936),²⁰ the Convention between the United States of America and Mexico for the protection of migratory birds and game mam mals (1937),²¹ and the International Agreement for the Regulation of Whaling (1938).²² But greater momentum and political impact was afforded by such organizations as World Wildlife Fund (founded 1961) and Greenpeace (founded 1971). The earlier sectoral approach was to a degree subsumed in a broader political and legal agenda culminating in the Rio Conference in 1992. An important step was the Brundtland Report, produced in 1987 by the World Commission on Environment and Development to address the challenge of finding multilateral paths toward sustainable development.²³ It was the first major report to focus on global sustainability, linking environmental and developmental issues; further, it proposed solutions based on international cooperation, and institutional and legal change.

In 1992, more than 100 governments met in Rio de Janeiro for the UN Conference on Environment and Development. The Earth Summit produced Agenda 21, a comprehensive plan of action calling for the ‘further development of international law on sustainable development, giving special attention to the delicate balance between environmental and developmental concerns.’²⁴ It also produced the Rio Declaration on Environment and Development,²⁵ containing 27 principles linked to the concept of sustainable development, and the non-binding Authoritative Statement of Principles for aReferences(p. 356) Global Consensus on the Management, Conservation and Sustainable Development of All Types of Forests (the Forest Principles).²⁶ In addition, the Convention on Biological Diversity (Biodiversity Convention)²⁷and the Framework Convention on Climate Change (UNFCCC)²⁸ were opened for signature.

A number of candidate legal principles have emerged from this ferment of activity: the more important of these may be briefly reviewed.

(A)  The Preventive Principle²⁹

As the International Court has observed, the ‘often irreversible’ character of environmental damage, and the limitations of reparation after the fact, mean that prevention is of the utmost importance.³⁰ The preventive principle requires action to be taken at an early stage. It is supported through a wide range of domestic and international measures directed at prohibiting harmful activities and enforcing compliance with standards.

In 2001 the ILC adopted the Draft Articles on the Prevention of Transboundary Harm from Hazardous Activities.³¹ This was the result of dividing its work on transboundary harm into two parts,³² the other pertaining to liability for transboundary harm.³³ The Draft Articles dealing with prevention ‘apply to activities not prohibited by international law which involve a risk of causing significant transboundary harm through their physical consequences’. Limiting activities to those ‘not prohibited by international law’ was ostensibly intended to separate issues of international liability from the topic of responsibility.³⁴

The Draft Articles draw on other established principles of international environmental law. For example, the requirement that a state ‘shall take all appropriate measures to prevent significant transboundary harm or at any event to minimize the risk thereof ’ invokes the precautionary principle, though the formulation used hasReferences(p. 357) been criticized.³⁵ Draft Article 7 includes environmental impact as a tool to assess the likelihood of transboundary harm. In requiring co-operation between states to prevent transboundary harm the Draft Articles also rely on the dynamics of international politics and supporting structures of international law to implement the provisions of any convention based upon them. Seeking to address circumstances which formed the basis of disputes in cases such as Trail Smelter, the ILC also sets out the ‘fundamental principle that the prior authorization of a state is required for activities which involve a risk of causing significant transboundary harm undertaken in its territory or otherwise under its jurisdiction or control’.

Despite the uncertainty surrounding their future status, the Draft Articles provide an authoritative statement on the scope of a state’s international legal obligation to prevent a risk of transboundary harm.³⁶

(B)  The Precautionary Principle³⁷

Probably the best known of the still evolving legal principles of environmental protection is the precautionary principle. This has been described as ‘an attempt to codify the concept of precaution in law’³⁸ where ‘precaution’ is defined as a strategy for addressing risk.³⁹ It concerns ‘the manner in which policy-makers, for the purposes of protecting the environment, apply science, technology and economics’.⁴⁰ Although well known, it is difficult to define. Sands observes that there is ‘no uniform understanding of the meaning of the precautionary principle among states and other members of the international community’.⁴¹ It has been noted that the consequences of applying a precautionary approach differ widely, depending on the context.⁴²

Different permutations of the precautionary principle are found in numerous multilateral instruments, such as the UNFCCC and the Biodiversity Convention. The precautionary principle can be interpreted to imply that precautionary regulation is justified when there is no clear evidence about a particular risk scenario, when the risk itself is uncertain, or until the risk is disproved.⁴⁵ The precautionary approach was affirmed as an obligation of sponsoring states in the advisory opinion of the ITLOS Seabed Disputes Chamber.⁴⁶

(C)  The Concept of Sustainable Development⁴⁷

Although emerging as a distinct field of scholarship, the existence of sustainable development as a distinct legal concept, that is, one which gives rise to or defines actionable rights, is controversial. Given the breadth of the concept, which includes trade, investment, and social concerns, it can be argued that sustainable development is better understood as a collection, or collocation, of different legal categories, and as a ‘general guideline’.⁴⁸

The most commonly cited definition, from the Brundtland Report, is ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’.⁴⁹ Development, a process of change toward improving quality of life for human beings and their communities, is said to be sustainable when it is achieved by the integration of social, economic, and environmental considerations in a way that provides for and protects the long-term well-being of populations. The field of sustainable development law refers to the emerging body of legal instruments, norms, and treaties directed at implementing this balance, as well as to the distinctive procedural elements (often based upon human rights law) underpinning them. The objective of sustainable development is increasingly included in general economic treaties and regional integration treaties.⁵⁰

References(p. 359) (D)  The Polluter-Pays Principle

Birnie, Boyle, and Redgwell describe the principle as ‘an economic policy for allocating the costs of pollution or environmental damage borne by public authorities’ with ‘implications for the development of international and national law on liability for damage’.⁵³ It is clear from the language of Article 16 of the Rio Declaration that the principle is essentially programmatic and hortatory: ‘it is doubtful whether it has achieved the status of a generally applicable rule of customary international law…’.⁵⁴ Its content is vague; it is unclear for example whether it entails strict liability. If so, it goes beyond normal principles of state responsibility for damage affecting the legal interest of another state.

(E)  The Sic Utere Tuo Principle

The general obligation of states to ensure that activities within their jurisdiction and control respect the environment of other states (and of areas beyond national control) was affirmed by the International Court in Legality of the Threat or Use of Nuclear Weapons.⁵⁵

(F)  The Obligation of Environmental Impact Assessment⁵⁶