In 1996, the Madagascan state enacted Law 96-025 (the GELOSE Law), which transferred the management of certain renewable natural resources to local populations by means of negotiated contracts. This legal strategy was innovative in many ways, namely by prescribing the use of Dina, a local traditional convention, in management-transfer contracts. By using Dina, the state claimed to reconcile the “legal” with the “legitimate” and to favour a sustainable management of these resources. This article focuses on the conditions of legitimacy of environmental norms in a pluralistic legal context marked by globalization. The use of Dina has not in fact contributed to an increased legitimacy of environmental norms, thanks to significant differences between its use and local regulatory procedures, insufficient governmental coordination in the implementation of Law 96-025, and a lack of resonance of sustainable development.