The 40th Canadian Parliament was in session from November 18, 2008 to March 26, 2011. It was the last Parliament of the longest-running minority government in Canadian history that began with the previous Parliament. The membership of its House of Commons was determined by the results of the 2008 federal election held on October 14, 2008. Its first session was then prorogued by the Governor General on December 4, 2008, at the request of Prime Minister Stephen Harper, who was facing a likely no-confidence motion and a coalition agreement between the Liberal party and the New Democratic Party with the support of the Bloc Québécois (2008–2009 Canadian parliamentary dispute). Of the 308 MPs elected at the October 14, 2008 general election, 64 were new to Parliament and three sat in Parliaments previous to the 39th: John Duncan, Jack Harris and Roger Pomerleau.

There were three sessions of the 40th Parliament. On March 25, 2011, the House of Commons passed a Liberal motion of non-confidence by a vote of 156 to 145, finding the Conservative Cabinet in contempt of parliament, an unprecedented finding in Canadian and Commonwealth parliamentary history. On March 26, 2011, Prime Minister Stephen Harper subsequently asked Governor General David Johnston to dissolve parliament and issue a writ of election.

40th Canadian Parliament

Party standings

The party standings as of the election, and at dissolution, were as follows:

40th Canadian Parliament

Resignations and by-elections

NDP MP Dawn Black resigned her seat of New Westminster—Coquitlam effective April 13, 2009, to run (successfully) in the provincial riding of New Westminster in the 2009 British Columbia general election. The NDP's Fin Donnelly won the seat left vacant by Black in a by-election on November 9, 2009.

40th Canadian Parliament

Independent MP Bill Casey resigned his seat of Cumberland—Colchester—Musquodoboit Valley effective April 30, 2009, to accept a job as the Nova Scotia Department of Intergovernmental Affairs' senior representative in Ottawa. He was a former Conservative who voted against the 2007 budget, claiming that it broke the Atlantic Accord with his province and Newfoundland and Labrador, and was subsequently expelled from the Conservative caucus. Scott Armstrong, the Conservative candidate, won the by-election for this seat on November 9, 2009.

Bloc Québécois MP Paul Crête resigned his seat of Montmagny—L'Islet—Kamouraska—Rivière-du-Loup on May 21, 2009, to run in a provincial by-election in Rivière-du-Loup. Conservative Bernard Généreux won the November 9, 2009 by-election for this seat.

Bloc Québécois MP Réal Ménard resigned his seat of Hochelaga on September 16, 2009, to run in Montreal's municipal elections. On November 9, 2009, Daniel Paillé won this seat for the Bloc in a by-election.

New Democratic Party MP Judy Wasylycia-Leis (Winnipeg North) resigned from the House on April 30, 2010, to run (unsuccessfully) for the mayoralty of Winnipeg. Liberal Kevin Lamoureux won the by-election to replace her on November 29, 2010.

Liberal MP Maurizio Bevilacqua (Vaughan) resigned from the House effective August 25, 2010 to successfully run for mayor in Vaughan. Conservative Julian Fantino won the November 29, 2010 by-election to replace him.

Conservative MP Inky Mark (Dauphin—Swan River—Marquette) resigned from the House effective September 15, 2010 to run for mayor in Dauphin. Robert Sopuck held the seat for the Conservatives in a by-election held on November 29, 2010.

Bloc Québécois MP Jean-Yves Roy resigned from the House effective October 22, 2010, followed by Conservative MP Jay Hill effective October 25, 2010. Conservative MP Jim Prentice resigned from the House effective November 14, 2010 to take a position with CIBC. By-elections in these three ridings were not scheduled prior to the issue of the writ for the 41st general election.