In terms of legal developments, the principle that reflects most directly the engagement of international environmental law with the special situation of developing countries is the principle of common but differentiated responsibilities. This principle reflects ‘differential treatment’, or the adaptation of the rules of international law to take into account inequality between countries. This has taken different forms, including ‘contextual’ norms, which reflect the fact that not all countries have the same capacity to comply with universal norms. This also includes norms that are ‘differential’, where developed and developing countries take on different commitments.
The principle of common but differentiated responsibilities is one of the main principles of international environmental law, as reflected in the fact that it was the only principle of the Rio Declaration specifically restated at Rio+20 in the Future we Want and in the 2030 Agenda for Sustainable Development. In legal instruments, differential treatment measures can be found in virtually every environmental treaty adopted since the mid-1980s. Put differently, international environmental law has been structured around a global South-North axis for decades.
Yet, despite significant enduring inter-state inequality, there has been a progressive push to move away from differentiation. This is based in part on the impressive economic performance of some developing countries over the past three decades. One of the results of this attempt to rethink the bases for environmental law can be seen in the Paris Agreement that abandoned negotiated differentiated commitments in favor of individually determined commitments, known as nationally determined contributions. Yet, even the Paris Agreement reflects the fact that inter-state inequality cannot be wished away, and a number of differential measures are also included, such as with regard to funding.