Measuring influence in the European Union: Has the Lisbon treaty changed the balance of power?

Our objective is to assess a country’s influence in the EU Council of Ministers not merely on the basis of its voting weight, but on a more refined measure that also takes into account the voting behavior of other countries. A country that is likely to receive support from other countries, on the basis of a similarity of interests, or having a capacity to build stable ‘alliances’ will be more influential than a country with more votes, but which tends to be isolated in its policy preferences. We thus set out a novel quantitative methodology, based on Spearman’s rank correlation coefficient, for integrating in one single measure the voting weight and the degree of support enjoyed by each country.

We apply the methodology to a data set that is richer than existing data sets. The data on voting behavior is based on the voting records provided by the Council Secretariat; we include all the votes taking place under the Treaty of Nice. In contrast with the existing literature, we differentiate between yes votes, no votes, and abstentions; moreover, we also take declarations on votes into account.

Our measure of influence gives novel insights into the level of influence member states can exert on decision making. For example, many smaller member states manage to exert a bigger influence on decision making than big member states; even though the smaller states have a lower voting weight, they manage to receive more support from others. We further use this measure to assess whether the changes in voting weights from the Nice to the Lisbon Treaty have shifted the balance of power. It turns out that for some of the smaller member states a decrease in voting weight does not imply that they lose influence on decision making.