ABSTRACT
The 1992 Rio Earth Summit yielded two influential formulations of this principle of international law and North–South equity in sustainable development. The first, from the Rio Declaration, states that: In view of the different contributions to global environmental degradation, states have common but differentiated responsibilities. In the second, 192 signatory nations adopted this “common but differentiated responsibilities” (or CBDR) framework for assigning national climate change burdens through the climate change regime. Politically, CBDR remains a core ideal for burden-sharing arrangements associated with international climate policy, and of sustainable development more generally, but one around which agreement has been elusive. The United States has expressly rejected any interpretation of CBDR in international law that implies acceptance of “any international obligations or liabilities, or any diminution in the responsibilities of developing countries”. All CBDR formulations share the normative foundation for assigning national burdens for climate change in some version of the polluter pays principle, but interpret the demands of that principle differently.
