R. v. Beaulac,  1 SCR 768
Language rights must in all cases be interpreted purposively, in a manner consistent with the preservation and development of official language communities in Canada. To the extent that Société des Acadiens stands for a restrictive interpretation of language rights, it is to be rejected. The fear that a liberal interpretation of language rights will make provinces less willing to become involved in the geographical extension of those rights is inconsistent with the requirement that language rights be interpreted as a fundamental tool for the preservation and protection of official language communities where they do apply. Language rights are a particular kind of right, distinct from the principles of fundamental justice. They have a different purpose and a different origin. When s. 530 of the Criminal Code was promulgated in British Columbia in 1990, the scope of the language rights of the accused was not meant to be determined restrictively. The amendments were remedial and meant to form part of the unfinished edifice of fundamental language rights.
Arsenault-Cameron v. Prince Edward Island, 2000 SCC 1,  1 SCR 3
Section 23 of the Charter mandates that provincial governments do whatever is practically possible to preserve and promote minority language education. Its object is in part remedial, and it is not meant to reinforce the status quo by adopting a formal vision of equality that would focus on treating the majority and minority official language groups alike. A purposive interpretation of s. 23 rights is based on the true purpose of redressing past injustices and providing the official language minority with equal access to high quality education in its own language, in circumstances where community development will be enhanced. The historical and contextual analysis is important for courts in determining whether a government has failed to meet its s. 23 obligations, and should guide governmental actors in reaching appropriate decisions to give effect to s. 23. The fact that constitutional language rights resulted from a political compromise is not unique to language rights and does not affect their scope.
DesRochers v. Canada (Industry), 2009 SCC 8,  1 SCR 194
The principle of linguistic equality in the provision of government services involves a guarantee in relation to the services provided by the federal institution, and the content of this principle must be defined in light of the nature and purpose of the service in question. It is possible that substantive equality will not result from the development and implementation of identical services for each language community. In the instant case, it is difficult to imagine how the economic development services could be provided without the participation of the targeted communities in both the development and the implementation of programs, since that is the very nature of the services. The communities could therefore expect to have distinct content that varied from one community to another, depending on priorities established by the communities themselves. Insofar as North Simcoe, in accordance with the programs’ objectives, made efforts to reach the linguistic majority community and involve that community in program development and implementation, it had a duty to do the same for the linguistic minority community.
Société des Acadiens et Acadiennes du Nouveau-Brunswick Inc. v. Canada, 2008 SCC 15,  1 SCR 383
Section 20(2) of the Charter requires the RCMP to provide services in both official languages when acting as a provincial police force in New Brunswick pursuant to the agreement. The RCMP retains its status as a federal institution when it acts under a contract with a province. However, since each RCMP member has, under s. 2(2) of the New Brunswick Police Act, all the attributes of a provincial peace officer and is authorized by that province to administer justice there, he or she performs the role of an “institution of the legislature or government” of New Brunswick and must comply with s. 20(2) of the Charter. There is no transfer of responsibility for the administration of justice in the province. Under the agreement, New Brunswick retains control over the RCMP’s policing activities. The provincial Minister of Justice discharges his or her constitutional obligations through the RCMP members designated as New Brunswick peace officers by the provincial legislation. Consequently, the RCMP does not act as a separate federal institution in administering justice in New Brunswick; it assumes, by way of contract, obligations related to the police service function set out in the provincial legislation. Furthermore, the functions for which the RCMP is responsible are government functions that are subject to specific constitutional obligations. The RCMP may not take on such functions without assuming the obligations associated with them. Thus, it is as a result of the agreement that the RCMP, by participating in a function of the New Brunswick government, has constitutional obligations imposed on it under s. 20(2) of the Charter.