Consider the case of the North American Free Trade Agreement (NAFTA), under which many goods produced in Mexico enter the United States duty free, while imports produced in other countries face U.S. tariff barriers. Because NAFTA was designed primarily to benefit firms and workers in North America, it is clear that goods manufactured elsewhere cannot be allowed to circumvent U.S. tariffs simply by being transshipped through Mexico on the way to the United States. Nor should it be possible for free riders to claim those foreign goods as “Mexican” that have received perfunctory labeling, repackaging, or processing in Mexico solely for ...