At the Maastricht European Council in December 1991, it was agreed that any European state whose system of government is founded on the principle of democracy could apply to become a member of the Union. In June 1993, the European Council at Copenhagen agreed that the countries with which association agreements were negotiated could in principle become members of the Union and that the future relationship with those countries could evolve on that basis. Criteria for membership of the European Union, the so-called "Copenhagen criteria", were also established. I quote: