Federal officials say the U-S has exhausted all possible means to avoid it's international trade obligations over country of origin labelling.
The WTO has ruled against COOL - for the fourth time.
Canadian government officials in Foreign Affairs, Trade and Development Canada and Agriculture and Agri-Food Canada say that decision is final, without the possibility of further appeal.
A joint statement released by Canadian and Mexican officials says those two countries will be seeking WTO authorization to take retaliatory measures against U-S exports.
Both countries are calling on the U-S to repeal COOL and comply with it's international obligations.
Agriculture Minister Gerry Ritz and International Trade Minister Ed Fast say the WTO ruling reaffirms Canada's long-standing position that COOL is blatantly protectionist and discriminates against Canada.