A NAFTA Chapter 19 panel (well, the majority, anyway) says yes. An excerpt:
A plain reading of the statute requires that all sales be analyzed in the dumping analysis as dumping refers to an aggregate concept. In directing the DOC to analyze aggregate amounts and compare average sales, the statute does not countenance a methodology, which permits the DOC to select some sales over others in the calculation of dumping margins. The wording of the statute requires that the DOC employ a methodology which analyzes all sales. Simply stated, the exclusion of positive value sales cannot be supported by the definition of aggregated amounts.
See pages 5-24. There's lots of good Charming Betsy/Chevron talk, for those are into that sort of thing.
There is a two member (Lichtenstein and Liebman) dissent that says zeroing does not violate U.S. law. See pages 53-90.
I hope to have something more to say about all this at some point, but it may be a while, so I thought I'd just mention the case for those who are interested.
