Canada is a federal state with a bicameral parliamentary system. This means that, in addition to the King or Queen, the Parliament of Canada consists of two legislative bodies: the House of Commons and the Senate.
The Senate was one of the fundamental elements of the 1867 compromise that established Canada as a federation. Representation by population was adopted in the House of Commons, and in return, Québec and the Maritime provinces garnered equal representation for each region in the Senate. This secured them a minimum level of representation in federal institutions, which was meant to protect the varied interests of Canada's regions and provinces in the development of federal legislation. It also was meant to allow the Senate to act as a counterbalance to the House of Commons.
According to section 22 of the Constitution Act, 1867, seats in the Senate are to be distributed across four regional divisions, each represented by 24 senators: 24 for Québec, 24 for Ontario, 24 for the Maritime provinces (10 for Nova Scotia, 10 for New Brunswick and 4 for Prince Edward Island) and 24 for the Western provinces (6 for Manitoba, 6 for British Columbia, 6 for Saskatchewan and 6 for Alberta). When Newfoundland and Labrador joined the federation in 1949, they were given 6 seats in the Senate, and the Northwest Territories, Yukon and Nunavut are represented by 1 senator each, bringing the current total number of senators to 105.
The Constitution states that each senator must reside in the province or territory for which they are appointed. For Québec senators, an additional condition applies: Québec is divided into electoral divisions, and each senator must reside (or have their real property qualification) in the electoral division they are appointed to represent. The aim of this additional requirement, at the time it was set out, was to ensure that a certain number of Québec's 24 senators represented the English-speaking minority, whose members were geographically clustered in particular electoral divisions.
Senators, including Québec senators, are selected by the prime minister of Canada and officially appointed by the governor general. Québec therefore does not have a say in choosing the individuals who are called to represent it in the Senate.
Since the 1960s, Québec has been proposing Senate reform as part of a broader constitutional reform movement. Québec has held that any reform of Canada's federal institutions must include increased provincial participation in the senatorial appointment process and ensure proper representation of the provinces in the Senate.
Québec is of the view that Senate reform can only be achieved through multilateral negotiations. To that end, in November 2007, the National Assembly of Québec 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.
From 2006 to 2012, the federal government tabled no fewer than eight bills to either turn the Senate into an elected house, limit the tenure of senators to a fixed term (of 8, 9 or 10 years), or both. The Constitution of Canada, however, stipulates that the "method of selecting Senators" can only be amended multilaterally, with the assent of the Senate, the House of Commons, and the legislative assemblies of at least seven provinces representing at least fifty percent (50%) of the population of all the provinces (the "7/50 formula" set out in paragraph 42(1)(b) of the Constitution Act, 1982). Moreover, in 1979, the Supreme Court ruled that the essential characteristics of the Senate could not be modified unilaterally (Re: Authority of Parliament in relation to the Upper House,  1 SCR 54, p. 67).
In April 2012, the Québec government referred a question to the Court of Appeal of Québec on issues pertaining to the constitutionality of the measures set out in Bill C-7, which at that time was the last Senate reform proposal tabled by the federal government. Titled An Act respecting the selection of senators and amending the Constitution Act, 1867 in respect of Senate term limits, Bill C-7 was divided into two parts. Firstly, it set out an electoral framework that was to be the "basis for the selection of Senate nominees." If a province enacted legislation on senatorial elections that was substantially in accordance with the stipulated federal framework, the prime minister of Canada would have had to "consider" the election results when recommending Senate nominees to the governor general, who officially appoints senators. Secondly, Bill C-7 would have amended section 29 of the Constitution Act, 1867, stipulating that senators would henceforth be appointed for a single term of nine years. Currently, section 29 states that a senator serves until they reach retirement age, which is set at 75 years of age.
On October 24, 2013, the Court of Appeal of Québec issued an opinion favourable to the Attorney General of Québec's position, declaring that Bill C-7, if passed, would have been unconstitutional, as the measures it contained pertained to the "powers of the Senate and the method of selecting Senators." These matters are covered by paragraph 42(1)(b) of the Constitution Act, 1982, which refers to the 7/50 formula (Projet de loi fédéral relatif au Sénat (Re) , 2013 QCCA 1807). The Attorney General of Canada had argued that the method of selection of senators was untouched by the bill, as the method would remain by appointment (not election), with the prime minister of Canada and governor general retaining their prerogative as to the final selection of nominees, regardless of the election results. He also argued that the length of a senator's tenure was not a matter subject to the multilateral procedure for constitutional amendment.
On February 1, 2013, the federal government also turned to the courts, filing a reference to the Supreme Court of Canada with respect to Senate reform. The government asked the Court to determine the procedure applicable for:
The hearings on the federal reference took place in November 2013. Aside from Yukon, all the provinces and territories intervened. The Supreme Court also appointed two friends of the Court (amicus curiae) to submit briefs, given the complexity and importance of this constitutional case.
On April 25, 2014, the Supreme Court found in favour of the Attorney General of Québec (and the other interveners who had submitted essentially the same arguments) on all questions put before it (Reference re Senate Reform,  1 SCR 704). It thus corroborated the essence of the conclusions reached in the Court of Appeal of Québec's opinion. It also concluded that the unanimous consent of both houses of the federal Parliament and all the provincial legislative assemblies was required to abolish the Senate (section 41 of the Constitution Act, 1982), thereby recognizing that all of the provinces had the right to dissent to the abolition of the Senate.
Moreover, the Supreme Court concluded that the federal Parliament could unilaterally repeal the real property qualification requirement for the 81 senators not from Québec. However, the consent of the National Assembly of Québec would be required for any amendment of the real property qualification requirement for the 24 senators representing Québec, including the full removal of the requirement for all 105 senators, as the Constitution contains a "special arrangement" for Québec senators.
The reference is significant for Québec, because it is one of the few decisions in constitutional case law that addresses a fundamental change to a federal institution lying at the heart of the 1867 compromise that established Canada as a federation, along with the role that Québec and the other provinces are expected to play with respect to such a change.