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2.2 The Customary International Law

Summarizing we can state that international environmental law is the body of international law that concerns the protection of the global environment. Originally associated with the principle that says that states must not permit the use of their territory in such a way as to injure the territory of other states, international environmental law has since been expanded by a plethora of legally-binding international agreements. These encompass a wide variety of areas that have potential issues, from terrestrial, marine and atmospheric pollution through to wildlife and biodiversity protection.

The key constitutional moments in the development of international environmental law are:

•   The 1972 United Nations Convention on the Human Environment (UNCHE), held in Stockholm, Sweden

•   Publication of the 1987 Brundtland Report, Our Common Future, which coined the phrase ‘sustainable development’

•   The 1992 United Nations Conference on Environment and Development (UNCED), known as the Earth Summit, held in Rio de Janeiro, Brazil

As a core principle of the environmental law of nations it was determined at the Stockholm conference in 1972 that states are entitled to exploit their own resources, but that it is also their responsibility to ensure that actions originating in their territory are not causing any damage to the environment of other states. This policy is known today as ‘customary international law’. This law includes all norms and rules that countries follow as a matter of custom, and they are so prevalent that they bind all states in the world. When a principle becomes customary law is not always clear cut and states not wishing to be bound put forward many counter arguments.

Examples of customary international law relevant to the environment include:

•   The duty to warn other states promptly about emergencies of an environmental nature and environmental damage to which another state or states may be exposed

•   Principle 21 of the Stockholm Declaration (‘good neighbourliness’).

However an obligation of the state to take certain actions (for example, a prohibition of any transboundary damages to the environment) cannot be deduced from customary international law; at most there is an obligation to adhere to due diligence, which obtains generally between states (see Simonis 2003: 227). Nevertheless we can proceed on the assumption that international environmental law will gain ever-increasing importance. This will ultimately depend on how fully the principles pronounced in the 1972 Stockholm declaration will be implemented in cross-national stipulations. A special role in this process could also be played by the concept of ‘the common concern of humankind’, which has been confined so far to climate protection and biodiversity. And the United Nations Framework Convention on Climate Change (UNFCCC), the international treaty produced at the Earth Summit in 1992 could eventually mean that countries will take their obligations against global environmental problems more seriously—particularly with regard to North–South relations.