Canada's constitution governs the legal framework of the country and consists of written text and unwritten traditions and conventions. The Constitution includes the Canadian Charter of Rights and Freedoms, which guarantees basic rights and freedoms for Canadians that, generally, cannot be overridden by legislation of any level of government in Canada. It contains, however, a "notwithstanding clause", which allows the federal parliament and the provincial legislatures the power to override some other sections of the Charter temporarily, for a period of five years.
The position of Prime Minister, Canada's head of government, belongs to the leader of the political party that can obtain the confidence of a majority in the House of Commons. The Prime Minister and their Cabinet are formally appointed by the Governor General (who is the Monarch's representative in Canada). However, the Prime Minister chooses the Cabinet, and by convention, the Governor General respects the Prime Minister's choices. The Cabinet is traditionally drawn from members of the Prime Minister's party in both legislative houses, and mostly from the House of Commons. Executive power is exercised by the Prime Minister and Cabinet, all of whom are sworn into the Queen's Privy Council for Canada, and become Ministers of the Crown. The Prime Minister exercises vast political power, especially in the appointment of other officials within the government and civil service. Michaëlle Jean has served as Governor General since September 25, 2005, and Stephen Harper, leader of the Conservative Party, has served as Prime Minister since February 6, 2006.
The federal parliament is made up of the Queen and two houses: an elected House of Commons and an appointed Senate. Each member in the House of Commons is elected by simple plurality in a "riding" or electoral district; general elections are called by the Governor General when the Prime Minister so advises. While there is no minimum term for a Parliament, a new election must be called within five years of the last general election. Members of the Senate, whose seats are apportioned on a regional basis, are chosen by the Prime Minister and formally appointed by the Governor General, and serve until age 75.
Canada's four major political parties are the Conservative Party of Canada, Liberal Party of Canada, New Democratic Party (NDP), and the Bloc Québécois. The current government is formed by the Conservative Party of Canada. While the Green Party of Canada and other smaller parties do not have current representation in Parliament, the list of historical parties with elected representation is substantial.