No, I wouldn't suggest that it's an American body. It's a private adjudicative or a quasi-private adjudicative body.
I mentioned the fact that the cases are often heard in Washington, which doesn't make it an American regime. I also made a point, though, about the place of arbitration. That's a determination the tribunal makes, and in claims against Canada that's usually some place outside the country, which means that only a court in that jurisdiction has the authority to review an arbitral award.
So it's the removal from the purview of Canadian courts and from the purview of Canadian elected officials that I find problematic with this regime--and I think you should as well--not necessarily to an American body but to one that sits outside the framework of Canadian law and outside the framework of the Canadian Constitution. It exists in an international law space largely created to resolve commercial disputes, not disputes about public policy and law. That's the concern.