Well the WTO rulings on lumber and agro are mixed. In the case of lumber they state that the duty applied by the US contravenes NAFTA - not that the duty concept in general is incorrect.
Unilateral agro subsidy reduction would be much preferable but politically no one will do it. Subsidizing farmers through marketing boards, quota's, price supports and tariffs is insane.
It would stimulate 3rd world trade as well, and set a good example for all to follow.
I would never argue that the US is a capitalist market - far from it. Big Government, over taxation, over regulation and general interference is rife. However, Canada, without a strong military, real security at our borders and without working with the US at an adult-partnership level, will never create the environment needed to ensure that trade is soundly protected.
Trade and alliance patterns are very much intertwined. Canada has been free riding off the US military for far too long.