VOCAL 2024
Abstract Submission

30. Voting power in the Council of the European Union: A sensitivity analysis

Invited abstract in session WD-2: Applications, stream Game theory.

Wednesday, 12:00 - 13:30
Room: C 103

Authors (first author is the speaker)

1. Laszlo Csato
Institute for Computer Science and Control (SZTAKI) and Corvinus University of Budapest
2. Dora Greta Petroczy
Central Bank of Hungary

Abstract

The Council of the European Union (EU) is one of the main decision-making bodies of the EU. Many decisions require a qualified majority: the support of 55% of the member states (currently 15) that represent at least 65% of the total population. We investigate how the power distribution, based on the Shapley–Shubik index, and the proportion of winning coalitions change if these criteria are modified within reasonable bounds. The influence of the two countries with about 4% of the total population each is found to be almost flat. The level of decisiveness decreases if the population criterion is above 68% or the states criterion is at least 17. The proportion of winning coalitions can be increased from 13.2% to 20.8% (30.1%) such that the maximal relative change in the Shapley–Shubik indices remains below 3.5% (5.5%). Our results are indispensable to evaluate any proposal for reforming the qualified majority voting system.

Keywords

Status: accepted


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