However we characterise normative “effectiveness”, international environmental law must be adaptable and capable of evolving to address new challenges and pursue ever-higher standards of environmental protection. Conventional regimes tend to be based on framework agreements, which institutionalise cooperation by establishing institutional machinery capable of elaborating more detailed environmental norms and standards. Older conventional instruments may also be understood in the light of current environmental standards and practices due to the “evolutionary interpretation” envisaged under the Vienna Convention. The almost universal participation of States in key global environmental treaties, as well as the pervasive influence of environmental norms on non-environmental treaty provisions, means that this “systemic integration” can promote more coherent and effective conventional regimes for environmental protection. In addition, a relatively relaxed approach is taken to recognition of the closely related customary rules, upon which environmental treaty rules tend to be based, due largely to the powerful law-making effect of a wealth of declarative instruments which rationalise the general principles of law relevant to environmental protection.
Quite apart from the traditionally recognised sources of international law, international environmental law relies heavily on atypical normative forms including, in particular, non-binding soft law instruments, which promote voluntary compliance, facilitate bilateral and multilateral environmental negotiations and provide a basis for the development of more specific binding norms. The rich infrastructure of intergovernmental-specialised agencies and programmes also plays a key role in providing the technical expertise required to achieve scientific consensus. International environmental law also tends to be procedurally sophisticated, requiring an open participative approach, especially where the environmental values concerned overlap with human rights requirements, thus ensuring that it can respond effectively to evolving societal expectations.
Finally, this field of international law is increasingly characterised by multilevel governance as well as by new forms of rules, standards and procedures emerging from non-traditional actors involved in the law-making process, suggesting a fluidity in the formation and evolution of international environmental rules, something which enhances their technical currency, broad legitimacy and applicability and, thus inevitably, their effectiveness.
As a new body of rules which has emerged very rapidly in recent decades, the “effectiveness” of international environmental law has long been a matter of concern, causing commentators to focus on various aspects of normative design and implementation.