EXAMPLE 21 The United Nations Security Council

The United Nations Security Council has five permanent members—China, France, Russia, the United Kingdom, and the United States—and ten other members that serve two-year terms. To resolve a dispute not involving a member of the Security Council, 9 votes are required, including the votes of each of the permanent members. (Thus, each permanent member has veto power.) The Security Council voting system is thus specified by describing its minimal winning coalitions as consisting of the five permanent members and four other members. Exercise 40 (page 500) is an opportunity to consider this interesting voting system in depth.