In Hincks v Gallardo,  O.J. No 69, the facts were that the men entered into a civil union in Britain. Same sex marriage was not available; the only choice was a civil union, which offered virtually identical rights and responsibilities to the parties as marriage would have done.
The Canadian court held that because the two did not have the choice to marry, and because the civil union regime was like a marriage in almost every respect, the two were "married" for Canadian purposes, and could be divorced under the Divorce Act.
This case is potentially important for immigration purposes. Till now, Immigration Canada has restricted recognition to marriages, but in light of this case, a Canadian who enters a civil union (also called a registered domestic partnerships) in a country where same sex marriage is not available, should be able to sponsor their non-Canadian partner on that basis.