On November 20, 2015, the WTO Appellate Body issued its report [3] in United States-Measures Concerning the Importation, Marketing and Sale of Tuna and Tuna Products. According to a news report [4], Mexico had first initiated dispute settlement proceedings in 2009 and won on a number of claims before both the original panel [5] and on the Appellate Body’s review [6] of its findings. In reaction to these decisions, the U.S. changed its tuna labelling regulations but Mexico instituted review proceedings, arguing these changes were insufficient to implement the Dispute Settlement Body’s recommendations and rulings. The Appellate Body agreed, finding that “the amended tuna measure modifies the conditions of competition to the detriment of Mexican tuna products in the US market; that such detrimental impact does not stem exclusively from a legitimate regulatory distinction; and, thus, that the amended tuna measure accords less favourable treatment to Mexican tuna products as compared to like tuna products from the United States and other countries and is therefore inconsistent with Article 2.1 of the TBT Agreement [7].”  The Appellate Body further disagreed with the panel’s method of analysis, stating that by looking at each of the three sets of labelling requirements separately, “the Panel failed to conduct a holistic assessment of how those various labelling conditions, taken together, adversely affect the conditions of competition for Mexican tuna products in the US market as compared to like US and other tuna products. Nor did the Panel give due consideration to the question of whether and how such detrimental impact resembles, in nature or extent, the detrimental impact that was found, in the original proceedings, to exist under the original tuna measure.” Finally, the Appellate Body addressed Article XX GATT [8], finding that “the distinctions drawn in the measure between these different fishing methods in different areas of the oceans” constituted “discrimination for purposes of the chapeau of Article XX.” It concluded by finding that the U.S. “has not demonstrated that these aspects of the amended tuna measure do not constitute arbitrary or unjustifiable discrimination within the meaning of the chapeau of Article XX” as “aspects of the design of the amended tuna measure are difficult to reconcile with the objective of protecting dolphins from harm. In particular, we consider that the determination provisions do not provide for the substantive conditions of access to the dolphin-safe label to be reinforced by observer certification in all circumstances of comparably high risk, and that this may also entail different tracking and verification requirements . . . .”