Canada has a bicameral parliamentary system, meaning that in addition to the Queen, the Parliament consists of two chambers, namely the House of Commons and the Senate.
In their respective opinions regarding the Senate (2013 and 2014), both the Québec Court of Appeal and the Supreme Court of Canada recalled that there is no doubt that the Senate was a fundamental component of the federal compromise in 1867 and the product of a consensus between the federal government and the provinces.1 Thus, in exchange for representation by population in the House of Commons, Québec and the Maritime Provinces obtained equal representation of the regions in the Senate. This secured them a minimum representation in federal institutions.2 In addition, it enabled the Senate to serve as a counterweight to the other chamber.
According to section 22 of The Constitution Act of 1867, Senate seats are distributed across four regional divisions, each represented by 24 senators: Québec , Ontario , the Maritime Provinces (Nova Scotia , New Brunswick , and Prince Edward Island ) and the Western provinces (Manitoba , British Columbia , Saskatchewan  and Alberta ). Later, when Newfoundland and Labrador joined Confederation in 1949, they were entitled to six senators, while the Northwest Territories, Yukon and Nunavut were entitled to representation by one member each, for a total of 105 senators.
The Constitution provides that a senator must be a resident of the province for which he or she is appointed. In the case of Québec, an additional condition applies: Electoral Divisions were created, such that each senator must be a resident (or have his or her Real Property Qualification) in the Electoral Division for which he or she is appointed. The aim of this clause, at the time, was to ensure that a certain number of Québec's 24 senators represented the English-speaking minority, which were grouped territorially in various ridings.
Québec senators are selected by the Prime Minister of Canada and officially appointed by the Governor General. The province therefore does not have a say in choosing the senators who are called to represent it in this chamber.
Since the 1960s, Québec has been proposing Senate reform in the context of a broader constitutional reform. Québec has held that any reform of the federal institutions must include increased participation of the provinces in the senator appointment process and ensure proper representation of the provinces within the Senate.3
Québec considers that Senate reform can be realized only through multilateral negotiations. To this end, in November 2007, the National Assembly unanimously passed a motion reaffirming that "no modification to the Canadian Senate may be carried out without the consent of the Government of Québec and the National Assembly".
For more information on this case, please consult the following documents:
Resolution of the National Assembly, November 7, 2007 (In french, PDF, 1 page, 134 ko).
1. Projet de loi fédéral relatif au Sénat (Re), 2013 QCCA 1807 (CanLII); Reference Re Senate Reform, 2014 SCC 32.
2. Re: Authority of Parliament in relation to the Upper House,  1 S.C.R. 54, page 67; Reference Re Senate Reform, 2014 CSC 32, para. 15.
3. Secrétariat aux Affaires intergouvernementales canadiennes. Québec's Positions on Constitutional and Intergovernmental Issues from 1936 to March 2001, Gouvernement du Québec, 2001, paras. 207, 313, 334.