1. THE TREATIES

2. Understanding the Treaties
A constitution is a document (or a set of documents) that sets out the general rules and principles by which a state is governed.
The EU does not have a constitution as such, but it has a body of treaties that have almost the same role, in the sense that they outline the rules by which the EU functions.
The process of integration was initially guided by treaties agreed between sovereign states, but through a process of constitutionalization those treaties have since taken on most of the features of a constitution.

3. EU Constitutional Norms

4. Treaty-Building
There have been two phases in the development of the treaties: the first lasted until 1986 and was mainly intergovernmental with little public input or interest (influenced by an atmosphere of ‘permissive consensus’), while the second has been more open and affected by public debate.
The process of treaty-drafting has mainly taken place in intergovernmental conferences (IGCs), the meetings of which have been subject to increased public and political pressures.
Lisbon may be the last major amendment to the rules of the EU for some time to come, given that most of the rules needed to allow it to function efficiently are now in place, and that ‘reform fatigue’ has settled in. It has also been argued that a plateau has been reached, and that there is a ‘constitutional settlement’ that obviates the need for additional treaties.

5. The EU Legal Order
The major treaties are the foundations of the European legal order, but the EU legal order has additional elements, including the following:
Accession agreements signed each time a new state joins the EU.
Agreements among sub-groups of member states (such as Schengen and the Social Charter).
The Charter of Fundamental Rights of the EU, adopted in 2000 and coming into force under the terms of Lisbon.
The European Convention on Human Rights, drawn up in 1950 by the Council of Europe.