An article in the Wall Street Journal (September 3, 2015) titled ” Auto Parts dispute Taps the Brakes on Pacific Trade Deal” describes disagreement between Japan, Mexico and the US regarding auto parts that will be considered free of duty under the Trans-Pacific Partnership agreement (TPP). Mexico prefers such parts to have at least 50% of their content from TPP countries while Japan uses components from Thailand and China (non TPP countries) and does not like such constraints. US automakers prefer some level in between that preferred by Japan and Mexico. Will the impact of such constraints on global supply chains cause a shift to TPP country of origin suppliers ? Should the importance of the auto component industry to Mexico be considered when setting TPP guidelines, given that other countries get rules changed to reflect their comparative advantage ? How should this balance be struck when setting TPP country definitions and should it be standardized across industries ?