Revisiting the hermeneutical function of sustainable development in international law: from an hermeneutical tool to an obligation to strive for sustainable developmentfrom an hermeneutical tool to an obligation to strive for sustainable development

The wide dissemination of sustainable development in international law has generated considerable academic interest. However, because of its evasive and flexible content academic commentary has often been at pains to ascertain sustainable development’s legal nature, which has proved a notion rebellious to legal classification. It is thus often seen as a political rather than a legal norm, or as a new branch of international law. On yet another analysis, sustainable development is to be understood as an “interstitial norm” capable of influencing the content of primary norms, thus exerting its normative influence as an interpretative tool in the hands of judges. Its interpretative function is certainly very significant. Judicial bodies have used it to legitimize recourse to evolutive treaty interpretation, as a rule of conflict resolution, or even to redefine conventional obligations. However, beyond this convenient hermeneutical function, by laying down an objective to strive for in hundreds of treaties, sustainable development primarily purports to regulate state conduct. As an objective, it lays down not an absolute but a relative obligation to achieve sustainable development. Such obligations are known as obligations of means or of best efforts. In other words, legal subjects are under an obligation to promote sustainable development