The Security Council: P5, veto, reform debate
The UN Security Council's structure, the P5 veto under Article 27, and the reform debate from Razali to the IGN, mapped for UPSC, FSOT, CSS and BCS.
The constitutional architecture
The Security Council is the United Nations' enforcement organ, created by Chapter V of the UN Charter (1945). Article 23 fixes its membership at fifteen: five permanent members (P5) — China, France, Russia, the United Kingdom and the United States — and ten non-permanent members elected by the General Assembly for two-year terms under an equitable geographical distribution. Note the historical detail: the original membership was eleven; the 1963 amendment (resolution 1991A (XVIII)), in force from 1965, enlarged the non-permanent tier from six to ten. The Russian Federation succeeded the USSR's permanent seat in December 1991, and the People's Republic of China replaced the Republic of China (Taiwan) under General Assembly resolution 2758 (XXV) of 25 October 1971.
Primary responsibility for peace
Under Article 24, members confer on the Council "primary responsibility for the maintenance of international peace and security," and Article 25 binds all members to accept and carry out its decisions — the only UN organ whose resolutions are legally binding on the entire membership. Its powers flow from two chapters. Chapter VI (Articles 33-38) covers pacific settlement of disputes and yields recommendations. Chapter VII (Articles 39-51) is the coercive core: Article 39 authorises the Council to determine the existence of a threat to the peace, breach of the peace, or act of aggression; Article 41 permits non-forcible measures (sanctions, embargoes, severance of relations); and Article 42 authorises the use of armed force. The Korean War authorisation (resolution 84 of 1950), the Gulf War mandate (resolution 678 of 1990) and the Libya intervention (resolution 1973 of 2011) are the canonical Chapter VII precedents.
The voting rule
Article 27 governs voting. Procedural matters require nine affirmative votes (Article 27(2)). Substantive matters require nine affirmative votes "including the concurring votes of the permanent members" (Article 27(3)) — this is the veto. Two practices, settled outside the Charter text, are exam favourites. First, an abstention by a permanent member does not count as a veto: this customary reading was confirmed by the International Court of Justice in its 1971 Namibia Advisory Opinion. Second, the "double veto" lets a P5 member first vote to classify a question as substantive (where it can then veto it). Procedural votes cannot be vetoed. The Article 27(3) proviso that a party to a dispute "shall abstain from voting" in Chapter VI decisions is honoured largely in the breach.
Subsidiary machinery
The Council operates through sanctions committees, the Military Staff Committee (Article 47, largely dormant), and peacekeeping operations authorised since the 1956 UN Emergency Force. The Uniting for Peace resolution (377A (V) of 1950) lets the General Assembly act when the Council is deadlocked by a veto — invoked over Suez (1956), and revived by resolution 76/262 of 2022 requiring an Assembly debate within ten working days of any veto cast.