Abstract
After the abandonment of the project of European Constitution, the idea of a simplified treaty was held by Member states to boost the institutional reform of the European Union. The treaty of Lisbon has to allow in particular Europe Twenty seven to work in a more effective and more democratic way. Since the beginning, the construction of Europe came true thanks to a succession of treaties negotiated by Member states: the treaty of Rome of 1957, the Single European Act of 1986, the treaty of Maastricht of 1992, the treaty of Amsterdam of 1997 and the treaty of Nice of 2000.
Since the 90s, the European Union (EU) is confronted with three challenges: the need to improve the efficiency of the decision-making of the EU following the enlargement, the concern to strengthen the democracy in the functioning of the community institutions and the will to increase the coherence of the foreign actions of the Union. These challenges are at the origin of the Declaration of Laeken (in December 15th, 2001) by which the heads of state and government make a commitment to reform the European institutions to return the more democratic and more effective Union.
