By-elections are held to fill a vacancy in the Canadian House of Commons.
Vacancies are caused by the death or resignation of a Member of Parliament or, more rarely, by the voiding of an election result by a court or as the result of an MP being expelled from the House of Commons.
In 1891, Thomas McGreevy (Quebec West) was expelled after being sentenced to a year in prison following his conviction for defrauding the government.
[2] This list below includes ministerial by-elections which occurred due to the requirement that Members of Parliament recontest their seats upon being appointed to Cabinet.
[3] Notable by-election upsets in Canadian history include the 1942 York South by-election in which the Co-operative Commonwealth Federation's Joseph Noseworthy upset Conservative leader and former prime minister Arthur Meighen's attempt to return to the House of Commons, Defence Minister Andrew McNaughton's defeat in the 1945 Grey North by-election, the 1949 by-election in Kamouraska where the Liberals, who had won the riding by a 55.8 percentage point margin in the previous general election, were defeated by the Independent Liberal candidate in the by-election; the 1943 Cartier by-election which the Liberals lost to the Labor-Progressive Party's Fred Rose; Walter Pitman's 1960 by-election victory in Peterborough as a New Party candidate, which was a catalyst for the creation of the New Democratic Party; Deborah Grey's 1989 by-election victory in Beaver River in which she won the Reform Party of Canada's first seat, and Gilles Duceppe's 1990 upset by-election victory in Laurier—Sainte-Marie on behalf of the newly formed Bloc Québécois.