Boundaries of Quebec under the Quebec Act.
The Quebec Act was an act of the British Parliament which received royal assent on 22 June 1774. The Quebec Act reversed many of the provisions of the Royal Proclamation of 1763, which had sought to encourage British settlement in Quebec by instituting English civil and criminal law and abolishing French civil law, which required tithing to the Catholic Church, and the seigneurial system, which made most of the population tenants of a handful of wealthy landowners.
It was assumed that the policies established by the Royal Proclamation would result in a steady stream of British immigrants into Quebec who would soon outnumber the Francophone inhabitants. However, this did not happen, since the original Thirteen Colonies had a more appealing climate and stronger ties with potential settlers in Great Britain. By the early 1770s it had become clear to Governor Guy Carleton that the province's Francophone population would not be assimilating to British ways, and that it would be better to appease them by restoring French civil law and granting religious freedom to Roman Catholics.
Under the provisions of the Quebec Act, French civil law and the seigneurial system were established, and the Test Act requiring adherence to the Protestant religion was replaced by an oath of loyalty to King George III that did not mention religion. The borders of the province of Quebec were also expanded to include the Great Lakes basin and the area north of the Ohio River.
The colonists of the Thirteen Colonies were unhappy with the Quebec Act for several reasons. The failure to establish an elected assembly in Quebec seemed an ominous portent, suggesting that the government of Lord North intended to abolish elected assemblies in the rest of British North America. Religious freedom for Catholics also appeared ominous, since the American colonists regarded Catholicism as synonymous with absolutism. The placement of the Ohio Country under the administration of Quebec outraged colonists who had been speculating in lands there since it put their ownership in question.
The timing of the passage of the Quebec Act, coming as it did at the same time as the Coercive Acts, convinced the American colonists that it was intended, along with the Coercive Acts, as punishment for the Boston Tea Party. As much as any of the actual Coercive Acts, the Quebec Act drove the American colonists into open rebellion, sparking the North American Rebellion.
Sobel does not say whether the Britannic Design of 1781 repealed any of the provisions of the Quebec Act, though Carleton's eagerness to incorporate Quebec into the Design suggests that it did not. If that is the case, then religious freedom for Catholics would have continued in Quebec under the Design, allowing them to stand for and vote for representation in the Quebec Council. Since the confederations of Indiana and Manitoba were split off from Quebec under the Design, presumbly those confederations also included religious freedom for Catholics.