1. Canada, the United Mexican States ("Mexico"), and the United States of America form one of the world's largest economic trading blocs, with investors of each country investing heavily in the territories of the others. The proposed appeal raises questions, none of which has been addressed by this Court before, regarding the scope of the protections which Canada, the United States and Mexico agreed to confer upon those investors through Chapter Eleven of the North American Free Trade Agreement (the "NAFTA"), as well' as issues concerning the scope and operation of the Vienna Convention on the Law of Treaties. The proposed appeal is of national and supra-national significance, because it has implications for the proper application of similar investment-protection treaties throughout the world, including many to which Canada is a signatory.

2. Indeed, even if the Court of Appeal is found to have reached the correct result in this particular case, Canada's broad international economic interests (and those of the Mexico and the United States of America) - as well as the interests of investors in the NAFTA Parties, and elsewhere - will be served by this Court's consideration of the important issues engaged by the proposed appeal. The particular importance of the issues raised by this case is reflected in the fact that both of the other NAFTA Parties - Canada and the United States - which were not parties to the underlying arbitration, intervened at the Court of Appeal, with Canada being granted leave to participate as a full party.