A treaty signed by the 12 member states of the European Union, agreed in February 1992, which came into effect on 1 November 1993. The treaty—officially known as the ‘Treaty on European Union’—envisages political union, with the concept of ‘union citizenship’; eventual monetary union under a European Central Bank; common policies on foreign affairs and security, with the Western European Union becoming the military arm of the Community; greater cooperation on domestic and environmental matters; some strengthening of the European Parliament; and ‘subsidiarity’, that is, an effective level of demarcation between the powers and responsibilities of the EU institutions and individual member states. The ratification by the member states was complicated by disagreements over certain clauses of the treaty. Britain refused to accept the Social Charter in 1992, a section of the treaty that protects the rights of employees, but agreed to it in 1997. However, Britain secured the right to refuse to adopt the single European currency. Denmark at first rejected the treaty in a referendum, but agreed to ratify it in a second referendum, having negotiated the right to ‘opt out’ of various provisions.