The formation of an economic union requires nations to surrender a large measure of their national sovereignty to supranational authorities in communitywide institutions such as the European Parliament. The ratification of the Maastricht Treaty (formally, the Treaty on European Union or TEU) by all of the 12 members created the European Union
The treaty set the foundation for economic and monetary union (EMU) with the establishment of the euro (€) as a common currency by Jan 1, 1999