The fragmentation of international environmental law is further exacerbated by the fact that each MEA can be characterized as a “legality” or a regime of its own, being equipped with autonomous institutional structures and procedures to ensure their further development [19] . In fact, almost each of one thousand MEA normally establishes a permanent plenary body, a secretariat, together with numerous advisory bodies and technical expert groups [20] . The plenary bodies – commonly referred to as “Conference of the Parties” (COP) – serve as a continuous forum for adoption of amendments to the existing framework treaty or conclusion of new related treaties, usually in the form of protocols or annexes [21] . To complicate the issue even further, the newly developed protocols often establish their own separate plenary organs, normally called the “Meeting of the Parties”, which at times do not have the same membership as the respective COP [22] . Indeed, following this process, many MEAs, including the 1985 Ozone Convention, the 1987 Montreal Protocol or the ¶{p. 471}1992 Framework Convention on Climate Change have developed into complex regulatory regimes, comprising several additional protocols, numerous amendments and additional decisions by COPs [23] . Indeed, the transpiring picture of environmental governance has been defined as “polycentric”, comprising multiple regime complexes, defined as “functionally overlapping institutions that continuously affect each other’s operations” [24] .

As should become clear from the description above, this highly-decentralized institutional structure of international environmental law represents a fertile soil for recurring inter-legality situations, where several regimes simultaneously regulate the same subject matter. To illustrate with just one example, both the climate change regime – represented by the UN Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol – and the Convention on Biological Diversity (CBD), address the issue of forests, albeit from different perspectives [25] . The former focuses on the role of forests in mitigating global warming by viewing them as carbon sinks or, alternatively, as a source of carbon emissions. To elaborate, since the main goal of the climate change regime is to encourage parties to reduce emissions, in practice, it gives more value to young trees and plants, which can act as effective carbon sinks by absorbing large amounts of carbon dioxide throughout their lifespans [26] . Instead, aged trees, that have already accumulated considerable amount of carbon, are seen as less valuable or potentially troublesome as they will eventually discharge ¶{p. 472}the carbon back to the atmosphere when they die and decompose [27] . Seen in this light, several scholars argued that replacing the old forests with industrial plantations of young fast-growing trees, capable of isolating more carbon, is a preferable option from the climate change perspective [28] . This stance, however, comes into conflict with the objectives of the biodiversity regime that seeks to protect the forest ecosystem holistically, by maintaining the balance between young and old plant lives [29] . As a result, the parties to both the UNFCCC and the CBD are placed under inconsistent obligations under the two related agreements, potentially disincentivizing them to fulfill their environmental obligations under either of the agreements [30] .

The problem of multiple sources overlapping in uncoordinated manner is further intensified by the fact that most of environmental regimes have weak compliance mechanisms in the form of reporting duties, essentially leaving it to the parties themselves to decide upon which of the competing obligations should be honored [31] . To clarify, out of more than thousand environmental agreements, only very few provide for some forms of judicial settlement mechanisms and those that do are rarely used [32] . As a result, the majority of contemporary environmental litigation takes place through non-environmental institutions, including human rights courts, as the next sections will demonstrate. And it is in this dimension that the second external inter-legality profile of international environmental law becomes visible.¶{p. 473}

Despite the absence of a central focal point in international environmental law, it is hardly disputed that the discipline represents an autonomous branch of international law, underpinned by common principles and regulatory standards [33] . This autonomous nature of environmental law becomes even more evident when it comes into interaction with other branches of international law, thereby creating “external” inter-legality situations. This section will address one of such inter-legality situations, namely the relationships between international environmental law and human rights law.

Although – as demonstrated in the previous section – international environmental law has developed as a separate regime with its own principles and institutions, its relationship with human rights law, for a long time, has been perceived as one of synergy and increasing integration [34] . Given the past achievements of human rights in improving human condition worldwide, as well as the natural link between human rights and environment, environmental issues, from the very beginning, have been viewed through the human rights paradigm [35] . In other words, the objectives of the two regimes have been long understood as corresponding, being both focused on improving the human well-being [36] . This approach to environmental protection was pioneered by the 1972 Stockholm Declaration on the Human Environment, which as the first principle, proclaimed the “fundamental ¶{p. 474}right to freedom, equality, and adequate conditions of life, in an environment of a quality that permits a life of dignity and well-being” [37] . As clear from the title and the wording of the Declaration, the document put environmental protection at the service of human interests, with the former being understood as an indispensable precondition for the enjoyment of human rights [38] . Although the Stockholm Declaration was not a legally binding instrument, it has been extremely influential in the normative framing of the relationships between the environment and human rights [39] . As noted by Fatma Zohra Ksentini, the former UN Special Rapporteur on Human Rights and the Environment, the document constituted a “qualitative leap”, which turned the ethos of environmental law from environmental protection to that of “a right to a healthy and decent environment” [40] . This subsumption of environmental law within the logic of the human rights regime was further exacerbated by the “implementation deficit” of international environmental law outlined above: in absence of its own judicial mechanisms, environmental claims have been increasingly adjudicated by human rights courts and predominantly within this instrumental paradigm [41] .