A special feature of the legal order of the European Union is reflected , among other things, in its institutional structure. Currently in the European Union there are seven institutions whose organization and activities are regulated by the Treaty on European Union and the Treaty on the Functioning of the European Union, based on the Lisabon Treaty, which came into force on 1 December 2009. These institutions are: the European Parliament, the European Council, the Council of Ministers, the European Commission, the Court of Justice of the European Union, the Court of Auditors and the European Central Bank. The European Parliament is the only directly elected body of the European Union and the representative body of 500 million citizens of the European Union. The European Council is the body which includes heads of state or prime ministers of the Member States, with the task of encouraging the development of the EU and acceptance of general policy guidelines and priorities. The Council of Ministers is, along with the European Parliament, the main legislative body of the European Union. The European Commission is the executive body of the European Union, responsible for proposing and implementing EU laws, supervising contracts and the daily management of the European Union. Court of Justice of the European Union is the highest court of EU law which interprets EU law and ensures its equal application to all Member States. The Court of Auditors performes audit of European Union finance. The European Central Bank is the central bank for the 19 EU countries that have adopted the euro currency. Agencies of the European Union, although not officially institutions, help the EU institutions 7 and national authorities in determining, preparation and assessment of specific measures in various policy areas.