A nice concept and how does the SCC propose to accomplish this?
Is it your opinion that Canada can exert no pressure on the United States?
Plainly Canada can't force compliance with international standards, but there are a variety of things that Canada could do to make life miserable for the United States, and there are a variety of things Canada could do or not do that would make life a lot nicer for the United States.
The SCC expects the Govt. of Canada to advance the rights of its citizens to the best of its ability.
It would be quite uncomfortable for the US if Canada were to recall its diplomatic staff, for example, it would throw a giant glaring spotlight on a horrendously undemocratic legal process. That's an extreme step, one that would hurt Canada too, certainly a last resort--but it would be effective. I can't imagine the undemocratic kangaroo court surviving long after that, it would essentially stay in the headlines until the issue was resolved.
Another severe, but not quite as extreme step, would be for Canada to fine the United States for its transgression and freeze some US assets inside Canada as restitution.
There are far milder steps that would have various levels of effect: So far the Govt. of Canada hasn't even gone as far as the Secretary General of the United Nations has--he at least lodged a diplomatic protest. It's a sad day when the UN SG is a better advocate for the rights of Canadian citizens than the Canadian government!