Political union is the last stage of the multinational integration process. It involves common home and judicial policies and a common foreign and security policy. According to the definition given above, a common policy entails a set of rules, decisions, measures and codes of conduct adopted by the common institutions set up by a group of states and implemented by the common institutions and the member states. A common policy does not exclude national policies, which continue to exist in all areas not covered by the decisions and rules agreed by the common institutions. Its development, however, requires the implementation by all the participating states of the common home and foreign policies agreed by the common institutions and the monitoring of this implementation by the common institutions. As long as these requirements are not met in certain sectors, political union, even though provided in a Treaty, is deficient or inexistent. In its place there may only exist intergovernmental political cooperation, leaving practically all freedom of action to the participants [see section 1.1.2].
At the same time as they were preparing the economic and monetary union stage, at Maastricht in 1991, europhilic nations were also projecting their political union. They, of course, encountered the opposition of their eurosceptic partners. The compromise solution that was found there and then was the partition of European integration into two Treaties (one on the European Union and one on the European Community) and into three construction pillars: the European Community - the first and main pillar; common foreign and security policy (CFSP); and justice and home affairs (JHA). The treaty establishing the European Community and the first pillar were to direct and regulate the first three stages of European integration: the customs union, the common market and the projected economic and monetary union using the Community method of decision-making by the common institutions. The Treaty on the European Union and the second and third pillars were intended to direct and manage the stage of political union using the intergovernmental cooperation method [see section 3.1].
It was soon apparent that this method was leading nowhere towards the construction of the second and third pillars of the Union and, therefore, the progress of political integration. The disappointment was most felt in the area of the third pillar, where there were matters of common interest to be regulated urgently: the free circulation of citizens and residents of the Member States, a common immigration policy and a common protection of the external borders of the Union from all sorts of illegal trafficking. Concerning the first of these matters, europhilic nations had already taken the lead by signing, in June 1990, the Schengen agreement for the abolition of border checks between themselves. But, the need was felt by all Member States, first, to generalise the experience gained by the pioneers to all the partners and, second, to extend it to other matters of common interest. This need led to the revision of the European Union Treaty, at Amsterdam in 1997. Most of the justice and home affairs pillar (notably questions relating to the free movement of persons, asylum, immigration, the crossing of external borders and judicial cooperation in civil matters) was placed under the Community orbit, i.e. under the Community decision-making procedure.
The treaty of Lisbon merged the European Union with the European Community, which ceased to exist, as of the coming into force of this treaty, on 1 December 2009. This merger put an end to the confusion between ''the Community'' and the ''Union'' and abolished the absurd notion of the ''three pillars'' of the Union. The provisions concerning the former JHA, now come under Title V of the Treaty on the functioning of the EU, named ''Area of freedom, security and justice'' (AFSJ).
The European Union now has a single legal personality under which it negotiates, signs and implements all its external commitments, policies and activities, including trade, aid to development, representation in third countries and in international organisations and foreign and security policy. However, despite the fact that all these external activities of the Union are placed under the responsibility of the High Representative of the Union for Foreign Affairs and Security Policy, the CFSP is still governed by intergovernmental cooperation, whereas commercial policy, aid to development and foreign relations are regulated by the EU's ordinary legislative procedure [see section 4.3]. This is the reason why CFSP is examined in this part and not in part VI, dedicated to the external policies of the Union.