The significance of the environment to existence calls for national, regional and international concern for its protection and preservation. The concept of common but differentiated responsibilities, which was enshrined as principle 7 of the Rio Declaration at the first Rio Earth Summit in 1992, is a reflection of this essence. Within the context of this relevancy, this paper appraised the principle of common but differentiated responsibilities in international environmental law, with a view to underscore the values and applicability of the principle; evaluate its nativity and international legal recognition; examine the principle in the light of climate change issues and international legal and regulatory responses; as well as constraints associated with the application of the principle. The paper adopted a doctrinal research approach through which the subject area was eliably examined and analysed. The paper found that non participation constraint, emission targets and per capital approach constraint, and comparability of action constraint, are the factors militating against the principle in the climate regime. The paper concluded that there should is the need for global environmental security through the application of the principle and therefore recommended that climate regime should accommodate the responsibilities of developing countries in the fight against climate change and not just laying all emphasis on the developed nations, as every nation contribute one way or the other in the common problem though in varying degrees.
Keywords: Common but Differentiated Responsibilities and Climate Change