A Dynamic Model of a Decision Making Body Where the Power of Veto Can Be Invoked

Classical analysis of the power of individuals or groups in decision making bodies tends to consider processes of coalition formation in isolation from each other. However, the results of attempts to form a winning coalition will affect the dynamics of coalition formation in the future, particularly when certain players are endowed with the power of veto. When a voter invokes their power of veto to block a generally popular motion, this is likely to provoke retaliation from the supporters of the motion. For this reason, even if a player is not in favor of a bill and can block it, it may be favorable for that party to abstain rather than veto in return for support regarding issues to be considered in the future. Hence, players should only use their power of veto if they are very strongly against a bill. In this paper, we present a model of voting in which the results of previous votes can affect the process of coalition formation. We present a model of such a dynamic voting game and present the form of an equilibrium in such a game. This theory is illustrated using an example based on the voting procedures used in the United Nations Security Council.