From a letter by Rep. Peter DeFazio to President Obama related to the NAFTA trucks case:
Mexico has made it clear that it chose products for retaliatory tariffs that would harm the districts or states of Members of Congress who led the charge to rid this program. For example, Oregon exports were specifically targeted including Christmas trees, wine, potatoes, pears, onions, and cherries. In essence, the government of Mexico is targeting U.S. elected officials who stand up for the safety of Americans. As you well know, such arbitrary tariffs are prohibited under the terms of WTO and NAFTA.
I thought this was pretty standard practice in coming up with trade retaliation. I wonder what his basis is for saying it violates WTO/NAFTA rules.