The purpose of this article is to explore the normative nature of the Ecosystem Approach in international environmental law. To do so, the article examines the implementation of this approach in two Mediterranean regimes: the Barcelona Convention and the General Fisheries Commission for the Mediterranean. As these two regimes have implemented the Ecosystem Approach by taking into account the experiences of other international regimes, they are representative of broader trends in relation to this concept. The examination reveals that the Ecosystem Approach operates as an interstitial principle: a norm that fulfils the functions of a principle with regard to other rules, but is devoid of normative autonomy. This understanding of the Ecosystem Approach brings clarity to a concept that is ambiguous yet is widely disseminated in environmental governance. It may also further the progressive emergence of the Ecosystem Approach as a general principle of international environmental law.
