Canada's prime minister holds an office no constitutional document ever created
Canada's government formally belongs to the King, who holds every power of state yet takes no political role. The prime minister, who actually steers the country, exists only through long-standing convention: the Crown must choose whoever can command the confidence of the elected House of Commons.
The structure dates from Confederation and the Constitution Act, 1867, which placed the Crown at the core of a Westminster-style parliamentary democracy. Legally the executive is the King-in-Council, meaning the monarch guided by a body called the King's Privy Council for Canada. That council, largely former ministers, chief justices and senior statesmen, rarely meets in full. Its advisory work falls almost entirely to the Cabinet, chaired by the prime minister, whose advice is normally binding, so the monarch reigns but does not rule.
Day to day, the King is represented by a governor general, appointed on the prime minister's advice, who since 1947 may exercise almost all royal prerogatives, though a few duties, such as assenting to certain bills, remain with the sovereign personally. Should the governor general be absent or incapacitated, an official called the administrator of Canada steps in. The actual business of government runs through more than 103 departments and agencies, the Canadian Armed Forces and a public service of over 300,000 people.
Vocabulary here differs from the United States. In Canada, the government means the prime minister, Cabinet and governing party, while the entire state, including legislature and courts, is properly the Crown. Americans would instead speak of an administration. Canadians also tend to lump provincial bodies under the federal label, even though the ten provinces and three territories govern quite independently in a highly decentralised federation.
Branding has been contested too. In late 2010 the Prime Minister's Office informally told departments to replace Government of Canada with Harper Government in their communications, after the same Cabinet had earlier promoted the slogan Canada's New Government. Prime ministers are usually drawn from the leader of the party holding the most Commons seats, and Cabinet members mostly come from that chamber, with a few senators.
Source: Government of Canada
