Strategic power in the European Union: Evaluating the distribution of power in policy games

In this paper we propose a new method to evaluate the distribution of power between decision making bodies in the European Union. Conventional methods that measure the voting power of players, such as the Banzhaf, Johnston, Holler, and Shapley-Shubik indices, are insufficient for this purpose. They take no account, in an endogenous way, of the differences in the abilities of players to affect the outcome of decision making, which are a result of the existence of political institutions. We propose a different way to measure decision making power based on the distance between a player’s ideal point and the equilibrium outcome of a game. While all previous indices are based on cooperative game theory, the index developed this paper is based on non-cooperative game theory, which has been the dominant thrust of theoretical politics and economics in the last years. The new index is applied to legislative procedures in the European Union. keywords: strategic power index, voting power indices, non-cooperative game theory, political institutions, European Union Strategic power in the European Union 1 The Council of the European Union, or Council in this contribution, is frequently referred to as the Council of Ministers, and prior to 1994 its full official name was the Council of Ministers of the European Communities. It should not be confused with the European Council, which is the meeting of the Heads of State, or their foreign ministers, of the Union’s member states. 1