12 April - Amid a lower than expected turnout, the electorate of
Hungaryvotes to join the European Union.[5]
16 April - The
Treaty of Accession 2003 is signed in
Athens by the 15 current member nations of the European Union and Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia. At 4,900 pages, it is the longest treaty in EU history.[6]