In the preceding Part, it was seen that international human rights law has managed to develop a quite elaborate, though not always fully coherent, normative framework for the progressive realisation of human rights and the avoidance of retrogressive developments. In order to assess whether corresponding (or at least similar) normative elements have also emerged in the context of international environmental law (‘IEL’), the ensuing chapters essentially follow the approach taken in Part I and survey a number of selected environmental treaty regimes.

If one looks for treaty language expressly relating to notions of progressive realisation or non-regression, the examples remain sparse. One of the very few examples in this regard is the North American Agreement on Environmental Cooperation (‘NAAEC’), the so-called environmental side agreement to the North-Atlantic Free Trade Agreement (‘NAFTA’), which provides the following:

On a relatively small geographical scale (in the relationship between Canada, Mexico and the United States), these substantive provisions indeed come remarkably close to the establishment of a non-regression obligation relating to the degree of protection established by domestic environmental laws. Although the substantive obligations are further complemented by a set of treaty bodies – the Secretariat, the NAAEC Council, and the Joint Public Advisory Committee, all of which make the Commission for Environmental Cooperation (‘CEC’) – and the Agreement even provides for its supervision through an inter-state consultation mechanism (including a sanctions mechanism) as well as an accountability procedure based on ‘submissions’ from the public relating to failures to ‘effectively enforce’ domestic environmental law, its overall effectiveness has been called into doubt. After the ‘renegotiation’ and eventual replacement of the NAFTA regime, a new environmental side agreement will be primarily limited to institutional and procedural questions. Instead, the above-mentioned substantive provision will be integrated into ew Chapter 24 of a novel trade agreement between the United States of America, Mexico and Canada.