Ontario is the only Canadian province where the Members of the provincial legislature refer to themselves as "MPPs," or "Members of the Provincial Parliament." In seven other provinces, the Members are designated "MLAs," for "Members of the Legislative Assembly." Parliamentarians in Quebec are called "MNAs," in reference to their membership in the National Assembly, while in Newfoundland, the Members call themselves "MHA," after their House of Assembly.
Section 69 of the British North America Act (now the Constitution Act, 1867), Canada's basic constitutional document, declared that "there shall be a Legislature for Ontario, consisting of the Lieutenant Governor and of One House, styled the Legislative Assembly of Ontario." Nevertheless, for some decades after Confederation the Members of the new provincial legislature referred to themselves variously as MLA and MPP, as did the official records. The latitude in official nomenclature the Members permitted themselves was undoubtedly a hang-over from the Union era (1841-1867), when the Members of the provincial legislature representing the combined Upper and Lower Canada were commonly identified by a variety of titles, including MPP, MLA and MHA.
It was not until 1938 that the Legislature was asked to collectively ponder the question of how its Members should be designated. In the spring of that year, the Member for St. Patrick, Lieutenant-Colonel Fraser Hunter, introduced a bill to fix the designation of the elected representatives as MP. He contended that the titles MPP and MLA were confusing, inaccurate, and undignified, and he was tired of trying to explain their meaning to visitors from elsewhere in the British Empire. However, Hunter failed to persuade his colleagues, who responded by passing a resolution of the House formally declaring their preference for the designation of MPP.
The debate over how provincial parliamentarians should be recognized soon flared up again, in the form of a debate between Arthur Beauchesne, the distinguished Clerk of the House of Commons, and Louis Philippe Pigeon, the Law Clerk of the Quebec Legislature. Beauchesne argued that the BNA Act clearly stated that "there shall be one Parliament for Canada" - such that provincial legislatures were of an inferior order of being, while Pigeon countered with a scholarly defence of the autonomy of provincial legislatures which is still cited by scholars in this field.
The terms of this engagement recalled an earlier intellectual donnybrook shortly after Confederation, when Fennings Taylor, the Clerk Assistant of the Senate, wrote a book contending that only the Canadian Parliament, and not the newly minted provincial legislatures, properly inherited the privileges and stature of the British House of Commons. He was opposed by S.J. Watson, the Parliamentary Librarian for Ontario, who argued that the new provincial legislatures could legitimately lay claim to the title of provincial parliament. Such debates echoed the political battles between the centralist Sir John A. Macdonald and Ontario Premier Oliver Mowat, the champion of the provincial rights school, which raged on throughout the late decades of the nineteenth century until the constitutional issues at stake were finally resolved in the provinces' favour by the Judicial Committee of the Privy Council.
As far as the Ontario Legislature was concerned, the matter appeared to be settled following the defeat of Lieutenant-Colonel Hunter’s bill in 1938. However, something of a revival occurred in the late 1970s and early 1980s, due to the efforts of former MPP Mel Swart (Welland-Thorold), who introduced a series of Private Member's Public Bills which, if any had passed, would have formally changed the Members’ designation from MPP to MLA. Mr. Swart believed that the term MPP caused confusion in the minds of the public, and that Ontario should conform to the practice in most of the other provinces. In 1986, Norm Sterling, MPP, introduced his own Private Member's Public Bill which would have established MPP as the official designation. None of these proposals was passed, leaving the 1938 resolution as the continuing authority for the title "MPP".