The European Union was established in 1993, as a complex political structure. It is composed of the two international organizations: the European Community and the European Atomic Energy Community that make up its first pillar together with the judiciary and internal affairs, while its separate second pillar constitutes the common foreign and security policy. Regarding the institutional structure of the European Union, it is important to mention the so-called "decision-making triangle" that is consisted of the European Commission, the European Parliament and the Council of the European Union. These institutions adopt general normative acts. Speaking of the institutions of the European Union, it is important to mention the European Council, which is responsible for the so-called "Guidance", the European Court of Justice that issues judgments and opinions that directly affect the legal system of the European Union. The advisory function belongs to the Economic and Social Committee and the Committee of the Regions. The signing and adoption of the Lisbon Treaty has made the European Union even more democratic, effective and capable of tackling global problems. The Lisbon Treaty has in the past, as well as nowadays, affectedall areas of activity of the European Union institutions.