It was seen in the preceding chapter that it remains quite difficult to consider non-regression as an already established, free-standing principle of IEL. Nonetheless, the above Parts I and II have sketched various traces of progressive realisation and non-regression in human rights law and selected treaty regimes of IEL. It was found that the basic ideas of progressivity and non-regression are indeed visible, in different shapes, in numerous human rights treaty regimes and MEAs. In the following, it will be argued that, building on various similarities between human rights treaties and MEAs, both areas of international law could greatly benefit from paying more attention to their commonalities. The present approach thus departs from the ‘human rights approaches’ to environmental protection that were discussed above. The present book seeks to tread into different territory by examining to what extent human rights law may be used to refine the interpretation, application and operation of MEAs. It should be conceded that the following discussion does not necessarily only describe the current state of human rights law and IEL (de lege lata), but also makes suggestions for the future development of both areas of international law (de lege ferenda).

In the present understanding, the now widely recognised concept of sustainable development already suggests that there is a fundamental interconnectedness between, inter alia, human rights law and IEL, that should guide the interpretation and application of treaty regimes (Section I.). Comparative law accounts are suggested as a possible means for a systematic reception from one treaty regime (e.g. a human rights treaty) into another, related treaty regime (e.g. an environmental agreement). In this regard, it will be considered what the role and use of comparative law methods in the context of international legal analyses can be (Section II.). With a view to the basic framework of treaty law, one may wonder whether the interpreter of a treaty text is barred from taking into account comparative arguments in his or her interpretive operation (Section III.). Furthermore, a general comparative framework for analysing human rights treaties and MEAs will be introduced (Section IV.), before one can turn to the results that could be gleaned from a comparative analysis of human rights treaties and MEAs (Section V.). This chapter will conclude with a discussion of the advantages and shortcomings of the suggested comparative approach (Section VI.).