Central and Eastern Europe Soviet Union; the independent states in former Yugoslavia (which were not considered part of the Eastern bloc); and the three Baltic states – Estonia, Latvia, Lithuania (which chose not to join the CIS with the other 12 former republics of the USSR). The CEE countries are further subdivided by their accession status to the European Union (EU): the eight first-wave accession countries that joined the EU on 1 May 2004 (Estonia, Latvia, Lithuania, Czech Republic, Slovakia, Poland, Hungary, and Slovenia), the two second-wave accession countries that joined on 1 January 2007 (Romania and Bulgaria) and the third-wave accession country that
Withdrawal from the European Union occur on 29 March 2019. Three territories of EU member states have withdrawn: French Algeria (in 1962, upon independence), Greenland (in 1985, following a referendum) and Saint Barthélemy (in 2012), the latter two becoming Overseas Countries and Territories of the European Union. Article 50, which allows a member state to withdraw, was originally drafted by Scottish cross-bench peer and former diplomat Lord Kerr of Kinlochard, the secretary-general of the European Convention, which drafted the Constitutional Treaty for the European Union. Following the failure of the ratification process for the European Constitution, the clause was incorporated into the Treaty of Lisbon