The principle of “common but differentiated responsibility” (CBDR), formalized at the 1992 United Nations Conference on Environment and Development in Rio de Janeiro, is ultimately pertaining to the matter of climate justice. Its basic meaning is first and foremost a “shared” moral responsibility between different groups of countries to address global climate change, nevertheless the proportions of such responsibility are differentiated. CBDR’s underlying concepts of fairness and equity has also been manifested in other global governance architectures than just the climate. The World Trade Organization, for example, knows the principle of “special and differential treatment” for developing and least-developed countries. The CBDR principle has gone through “ups and downs” in the past 30 years and the world has further evolved. While it is entering the fourth decade, it still remains relevant today.