The establishment of the European Communities in the ’80s was one of the first steps in the process of developing the European Union as we know it today. Creation of the European Union marked the beginning of a new phase in European countries that have made efforts to understand the need for the working team. Its fundamental principles were also established - freedom, democracy and human rights, aiming to promote economic and social progress. Through a series of international treaties adopted at European level structures have been established that we call the European Union today. These treaties, known as "modifying treaties" began with the Marshall Plan in 1947 and ended in 2009 with the well-known Lisbon Treaty. U.E. today operates through a system of supranational independent institutions that make decisions through negotiation with Member States. The most important institutions of the European Union are: the European Commission, European Parliament, European Council, European Court of Justice and the European Central Bank. Perhaps the most important achievement of the European Union is the creation of the European single market comprising a unified system of economic and financial laws which apply in all member states. Legal rules imposed by the European Union guarantees the free movement of people, goods, services and capital. European law promotes common policies in the field of justice and home affairs, environment, health, agriculture, commerce and agriculture. There is a clear set of rules within maritime domain, fisheries and regional development. It was also established a monetary union, the so-called “Eurozone” currently consists of 17 states. Union has a combined population of over 500 million, i.e. about 8 % of the world population. The European Union had an annual GDP of about 18 trillion U.S. dollars in 2011. That means it is the first in the world bringing together about 21 % of global GDP.