Deputy Prime Minister
The designation "Deputy Prime Minister" is strictly an honorary title conferred at the discretion of the Prime Minister on a member of the Cabinet. It has no standing in law, and does not carry any formal duties or tasks, though the Prime Minister may negotiate or assign specific tasks in conjunction with the title. Some prime ministers have elected not to appoint a Deputy Prime Minister, including Prime Ministers Joe Clark, stephen Harper, and Justin Trudeau.|
Role and Responsibilities
The title originates with Prime Minister Trudeau who first coined it when he designated The Honourable Allan J. MacEachen Deputy Prime Minister as well as Government Leader in the House of Commons in an interview with the press subsequent to the nomination of his Cabinet, September 16th, 1977. Since then there has been only The Right Honourable Joe Clark who has never named a Deputy Prime Minister.
From The Honourable Erik Nielsen's designation as Deputy Prime Minister, current practice holds that this title be assigned by "instrument of advice". An instrument of advice is essentially a private letter addressed to the Crown or its duly appointed representative, the Governor General, by the Prime Minister directly.
SOURCES: Library of Parliament and the Privy Council Office.
Former Deputy Prime Ministers
Prime Minister's Official Website