In spite of the recent failure of two referendums, the drafting of a constitution for the second biggest economic power in the world, the European Union (EU), remains a major event in the history of European integration. Whether the constitution or a revised version of it will come into force or not, several important questions emerge. How did an increased number of twentyfive member states reach a conclusion, whereas a lower number of fifteen had failed at previous intergovernmental attempts? In particular, how did the constitutional convention differ from previous intergovernmental conferences (iGCs) at which the EU exclusively bargained its treaty documents in the past? How can one explain the outcomes of the convention, which proposes redistribution of power and resources among twenty-five or more member states? This article uses the positions of the delegates of the EU's constitutional convention to examine bargaining in a setting with few formal rules. The authors use theoretical insights from a spatial model and new survey data to determine the implicit voting rule used at the convention. They find that the convention differed from previous IGCs because the convention was governed by consensus, whereas previous EU bargains on treaties had always required unanimous support. The level of consensus was higher than simple majority rule but lower than unanimity. Since this threshold impacted who won and who lost at the convention, the authors also examine the sources of bargaining power, such as delegates' distance to the status quo, distance to the median, population size, and domestic constraints. The results confirm several findings in the EU bargaining and two-level game literature, for example, that actors closer to the status quo hold a stronger bargaining position and that actors from larger member states are neither more likely nor less likely to win at the negotiating table than are actors from smaller states. The findings on the irrelevance of domestic constraints also indicate why the popular votes in France and the Netherlands failed.
Costly verification in collective decisions
