The 2005 UN World Summit was a pivotal event in the formal progression of the responsibility to protect (R2P) principles. Paragraphs 138–9 of the summit's outcome document articulated the fundamental responsibilities of states and the wider international community. The R2P approach was directly applied for the first time by the Security Council to the genocide in Darfur and most recently to the international response in Libya during the Arab Spring uprisings in 2011 and 2012. Since the late 1990s, the concept of R2P has evolved into what supporters now claim is a new type of responsive norm regarding how the international community should react to serious and deliberate human rights violations. The 2001 UN International Commission on Intervention and State Sovereignty co-chaired by Gareth Evans and Mohamed Sahnoun articulated in detail the principles of R2P. These principles were then formally endorsed by the majority of states at the 2005 UN General Assembly World Summit in New York.

At the 2005 summit, the international community almost unanimously endorsed the idea that states have a fundamental responsibility to protect their own citizens, and in most cases the citizens from other states, from gross human rights violations and other mass atrocities. However, the progression of R2P from concept to principle to formal ratification in 2005 has been a very difficult one with a great deal of disagreement over the validity of R2P as a substantive or even a developing norm in international affairs.