In 2002,
Lavanya Rajamani argued that developing countries would have an unfair economic advantage because they would not face the same restrictions as developed counties would. A climate change treaty would be ineffective without the participation of developing countries. The US has suggested that developing countries are not doing enough to satisfy their share of 'common responsibility for the problem' of climate change. Developing countries, however, argued that their carbon emissions are essential to their survival, while those of the developed countries are 'luxury emissions.' Christopher D. Stone argued that the meaning of the word 'differentiated' could be problematic as every agreement differentiates. He also says CBDR is "neither universal nor self-evident." Philippe Cullet points out that with CBDR, it may be difficult to determine the existence of specific customary norms. He suggests that CBDR, because it requires that actions be taken on the basis of capabilities and contributions made by countries to major global challenges such as climate change, it may make it difficult to determine specific customs. This is because CBDR demands that there be flexibility in application, thereby making it difficult for universally agreed-upon legal principles to be determined.
Todd Stern, then U.S. Special Envoy on Climate Change, said in his commencement speech at Dartmouth's 2012 graduation ceremony that the world can no longer have two distinct categories of countries having different responsibility for climate change mitigation. Countries should instead follow differentiation of a continuum, where states are required to act vigorously according to their own circumstances, abilities and responsibilities. He emphasized sharing the responsibility to reduce
carbon emissions between all countries instead of having a group of countries take the bulk of the responsibility for mitigation. == CBDR: Kyoto vs Paris ==