James Bowden, an graduate student in the School of Political Studies at the University of Ottawa (author of the excellent blog Parliamentum and contributor to iPolitics) has posted "1791: The Birth of Canada" on SSRN.
Here's the abstract:
"Canada" as a polity dates back to 1791, rather than to 1867.
This paper outlines how the polity established by the Westminster Parliament through the Constitutional Act, 1791 (the colonies of Upper and Lower Canada under the Imperial Crown) evolved, in a direct and unbroken line, into the modern Canadian state, a constitutional monarchy now under its own separate Crown of Canada. This polity's institutions -- General General, the political executive, the parliament, the courts, and the civil service -- evolved uninterrupted as the Westminster Parliament re-organized the British North American Crown colonies through the Constitutional Act, 1791, the Act of Union, 1841, and the British North America Act, 1867.
Consequently, the Government of Canada's "Canada at 150" campaign, which equates "Canada" as a polity to Confederation in 1867, is a misnomer. "Confederation at 150" would be a more accurate slogan because we are celebrating the sesquicentennial of Confederation, when the United Province of Canada became the Dominion of Canada and reorganized the existed Crown colonies into a federation, and not the sesquicentennial of "Canada" itself.