When it comes to the NAFTA discussion, one topic that has been brewing the longest, without permanent resolution, is trade in softwood lumber between the U.S. and Canada. …Like in previous rounds of this fight, Canada has been quick to hit back. In November 2017, Canada filed a NAFTA challenge to the CVD duties and in December 2017, filed a NAFTA challenge to the AD duties. Canada also followed up with a challenge at the World Trade Organization in November 2017, claiming that the U.S. used a controversial methodology know “zeroing” in its AD duty calculation. Zeroing is a calculation methodology where in situations that the foreign domestic prices minus the U.S. import price would result in a negative number, a zero is used instead. The use “zeroing” increases the AD duty higher than it would otherwise be. The use of “zeroing” has been struck down as inconsistent with WTO law in previous cases.