The Court concluded that the exclusion of Royal Canadian Mounted Police officers from unionization and collective bargaining was unconstitutional, overruling Delisle v Canada (Deputy Attorney General).

[3] In the years after Delisle, the Court expanded the scope of section 2(d): in Health Services and Support — Facilities Subsector Bargaining Assn.

The Court of Appeal for Ontario unanimously reversed the trial ruling, applying the "impossibility" test articulated in Fraser and finding no breach of section 2(d).

[4] The MPAO, joined by the British Columbia Mounted Police Professional Association, was granted leave to appeal to the Supreme Court of Canada.

The majority opinion sought to "clarify the scope of the constitutional protection of collective bargaining" recognized in BC Health Services and Fraser.

[6]The Court did not explicitly state that Fraser was overruled, instead reasoning that the "impossibility" referred to in that case described the effects of the law at issue, not the legal standard for finding a breach.

In the weeks after MPAO was decided, the Court rendered its decision in Saskatchewan Federation, concluding that the right to strike is constitutionally protected.