5. The zeroing reports represent a long-running dispute between the Appellate Body and panels – composed primarily of trade remedy experts – about the meaning of key provisions of the Antidumping Agreement. In their submissions, Mexico and several third parties have flayed the Panel for not adopting the Appellate Body’s findings in the various zeroing cases. While engaging in legal histrionics has dramatic value, the reality is that the Appellate Body recognized long ago in Japan – Alcoholic Beverages II that GATT and WTO reports are “not binding except with respect to resolving the particular dispute between the parties.” The Appellate Body has also indicated that panels are required only to “take into account” prior rulings on matters in issue. Here, the Panel carefully analyzed the Appellate Body’s reasoning in expanding a zeroing prohibition beyond average-to-average comparisons in investigations, and found that it could not agree. A reading of the Panel’s report will show that it responded in detail to each of the various rationales that have been put forward by the Appellate Body in its zeroing decisions. The Panel’s report reflects a sincere disagreement with the Appellate Body’s reasoning, not a lack of respect.
6. All of us want a strong WTO dispute settlement system that commands widespread respect and adherence. But no legal system can afford an unthinking adherence to precedent. Even in our common law system with its principle of stare decisis, the courts can and do reverse earlier rulings if they are convinced that a mistake was made. A legal system that cannot fix mistakes will lose credibility and eventually fall apart. Therefore, we urge the Appellate Body to approach this dispute with an open mind, and not to be cowed by emotional predictions by some of our friends that the world as we know it will end if some aspect of an earlier ruling is ever reconsidered. In view of the number of expert panelists that have disagreed with the Appellate Body’s previous findings on zeroing, and the criticism by respected academics of the Appellate Body’s zeroing rationales, it is simply not realistic or credible for our Mexican, Japanese, and European friends to try to shout down legitimate principled disagreement about whether the Antidumping Agreement and GATT 1994 Article VI contain a clear, broad-based prohibition on zeroing in all contexts.
The U.S. appellee's submission is here. I couldn't find the other participant's/third participants' submissions online to get the other side of the story.
This whole case must have been a delicate one for the U.S. lawyers, who had to say things like this to the Appellate Body: "The Appellate Body’s Interpretation of the Term "Margin of Dumping” Is at Odds with WTO/GATT Practice and the Ordinary Meaning of the Term."