Canada received the right to control its own domestic affairs when it

became a Dominion

Explanation:

(this happened back when Canada was colonized by the British empire). On the earlier stage of the colonization, People of Canada had to bow down to the rules and regulations imposed by the British empire and unable to make their own legislation.

In 1867, British empire decided to combine British colonies of Canada, Nova Scotia, and New Brunswick into one Dominion because it's easier to manage in British empire's perspective.