The constitutional Monarchy is practiced by the Government of Bhutan since 18 July 2008. The King is the head of state. The executive power is exercised by the Lhengye Zhungtshog or council of ministers, headed by the Prime Minister. Legislative power is vested in the bicameral Parliament, both the upper house, National Council, and the lower house, National Assembly. A royal edict issued on April 22, 2007 lifted the previous ban on political parties, ordering that they be created, in anticipation of National Assembly elections to be held the following year. In 2008, Bhutan adopted its first modern Constitution, codifying the institutions of government and the legal framework for a democratic multi-party system.