Canada has strong democratic traditions upheld through a parliamentary government within the construct of constitutional monarchy, the monarchy of Canada being the foundation of the executive, legislative, and judicial branches and its authority stemming from the Canadian populace.[94][95][96][97] The sovereign is Queen Elizabeth II, who also serves as head of state of 15 other Commonwealth countries and resides predominantly in the United Kingdom. As such, the Queen's representative, the Governor General of Canada (presently David Lloyd Johnston[98]), carries out most of the royal duties in Canada.[99]
The direct participation of the royal and viceroyal figures in any of these areas of governance is limited, though;[97][100][101][102] in practice, their use of the executive powers is directed by the Cabinet, a committee of ministers of the Crown responsible to the elected House of Commons and headed by the Prime Minister of Canada (presently Stephen Harper[103]), the head of government. To ensure the stability of government, the governor general will usually appoint as prime minister the person who is the current leader of the political party that can obtain the confidence of a plurality in the House of Commons and the prime minister chooses the Cabinet.[104] The Prime Minister's Office (PMO) is thus one of the most powerful institutions in government, initiating most legislation for parliamentary approval and selecting for appointment by the Crown, besides the aforementioned, the governor general, lieutenant governors, senators, federal court judges, and heads of Crown corporations and government agencies.[100] The leader of the party with the second-most seats usually becomes the Leader of Her Majesty's Loyal Opposition (presently Michael Ignatieff[105]) and is part of an adversarial parliamentary system intended to keep the government in check.
Each Member of Parliament in the House of Commons is elected by simple plurality in an electoral district or riding. General elections must be called by the governor general, on the advice of the prime minister, within four years of the previous election, or may be triggered by the government losing a confidence vote in the House.[106] Members of the Senate, whose seats are apportioned on a regional basis, serve until age 75.[107] Four parties had representatives elected to the federal parliament in the 2008 elections: the Conservative Party of Canada (governing party), the Liberal Party of Canada (the Official Opposition), the New Democratic Party (NDP), and the Bloc Québécois. The list of historical parties with elected representation is substantial.
Canada's federal structure divides government responsibilities between the federal government and the ten provinces. Provincial legislatures are unicameral and operate in parliamentary fashion similar to the House of Commons.[108] Canada's three territories also have legislatures, but these are not sovereign and have fewer constitutional responsibilities than the provinces and with some structural differences.[109][110]