Nash revisited: Bargaining Power at EU Intergovernmental Conferences

The EU treaties serve as a "constitution" for the European Union. They essentially establish the distribution of power between the levels of government and their institutions. Given this fundamental nature, treaty reforms are highly controversial whenever EU governments come together at Intergovernmental Conferences (IGCs). My paper sheds light on bargaining power at IGCs. I evaluate whether certain member states systematically get more while others regularly fail to shape the outcome. If so, what determines whether or not a state is successful? To model the negotiations and predict bargaining outcomes, I employ multidimensional variants of the Nash Bargaining Solution (NBS) (Nash 1950). The fact that treaty amendments require unanimity at the internatinal table as well as national ratifications gives rise to multiple variants of the Nash model: Apart from a symmetric version which essentially captures institutionalist ideas, I calculate asymmetric models that account for member states'' size, dependency on cooperation, and national ratification hurdles. While many theoretical models of international cooperation are based on the NBS, multidimensional empirical applications are scarce. Previous research has tested concurrent theories and models of bargaining power at single IGCs (König, 2007; Linhart, 2006; Slapin, 2006, 2008), while I propose a longitudinal design: I analyze five major reform steps, namely the Single European Act (1986), the Maastricht (1991), Amsterdam (1996), Nice (2000) treaties as well as the Rome (2004) Treaty.