CYIL vol. 11 (2020)

SILVANO DENEGA SOUZA CYIL 11 (2020) them, while these rulings come to get lost in the instructional, simplistic opinions of certain legal works, for they lack proper normative classification at the international stage. 4.2 Customary International Environmental Law International environmental law norms in the international legal system can be viewed more clearly when these arise directly from treaties. In fact, this has been the most effective way for the international community to discuss, understand and express concern in relation to the environmental protection. There is also the possibility that treaties themselves may predict evidence of the development of custom. 53 Bodansky argues that the pulverization of international environmental law in the form of treaties could undermine custom, yet it would still remain a source: ‘The growing importance of treaties suggests a diminished role for customary international environmental law. Nevertheless, many writers still consider custom an important source of international environmental law.’ 54 There is a perception of continuous movement and prospective practice of states regarding the implementation of international environmental agreements, considering the profusion of these instruments in the last decades. It is also a fact that this normalization has been targeted by critics due to the lack of an apparent hegemony in the debate, approval and practice process. Nevertheless, despite still heterogeneous, all those instruments repeatedly reinforce a single tendency; in other words, there is a known, evident convergence point: the environmental protection. Environmental protection may be considered the most relevant aspect of customary international environmental law, since it has been object of numerous multilateral and regional treaties which, directly or indirectly, regulate the environment subject, apart from providing guidance to paradigmatic decisions of international tribunals, United Nations resolutions, and reflecting in many other documents and practices proper to international law. The intent here is not to defend a point of view from which absolutely everything regarding the environmental protection could be qualified as custom. Nonetheless, several international instruments that encompass the matter share an easily identified feature, which is to almost always suggest a precautionary or sustainable development approach. These convergence points, as seen, could be indication of the existence of a custom. Notwithstanding this, perhaps the most common example of custom is that of the obligation to prevent cross-border pollution. This is said to be one of the most stable rules when it comes to customary international environmental law. 55 On the sources of international law listed under Article 38 of the Statute of the International Court of Justice, Christina Voigt states that ‘it is in particular customary law and general principles of law that seem most likely to capture the normative significance of sustainable development.’ 56 Furthermore, when it comes to international environmental law, two of these principles have been constantly discussed and are generally portrayed in agreements: the precautionary and sustainable development principles. 53 Brownlie (n 38) 5. 54 BODANSKY, Daniel, ‘Customary (And Not So Customary) International Environmental Law’ (1995) 3/1 Indiana Journal of Global Legal Studies 105, 106. 55 Ibid 112. 56 Voigt (n 35) 147.

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