How Brexit affects European Union power distribution

Abstract

The possible exit of the United Kingdom from the European Union will have profound economic and political effects. Here we look at a particular aspect, the power distribution in the Council of the European Union. Since the Lisbon treaty the exit does not require new negotiations as the success of a voting initiative only depends on the number and total population of the supporting member states. Using the Shapley-Shubik power index we calculate the member states' powers with and without the United Kingdom and update earlier power forecasts using the Eurostat's latest population projections. There is a remarkably sharp relation between population size and the change in power: Brexit increases the largest members', while decreases the smallest ones' powers.