Settling NAFTA and WTO Disputes : A Net of Parallel and Contradictory Commitments?

In May 2012, the Appellate Body of the World Trade Organization (WTO) issued a report on the labeling of tuna in a dispute between the United States and Mexico, known as the US — Tuna II (Mexico) case. The case has attracted a fair amount of attention, but not on the fact that it raised, at an early stage, procedural questions of utmost importance for the jurisdiction of the WTO. The article studies this issue of contradictory claims in matter of exclusive jurisdiction. It argues that 20 years of adjudication at the WTO has not solved the issue of conflicting claims. The first part develops the case of NAFTA Article 2005 as an instance of free trade agreement (FTA) containing a claim of exclusive jurisdiction. The second part reviews the obligations of WTO Members in matters of dispute settlement, paying particular attention to the last 20 years of jurisprudence on this issue. The article reaches the conclusion that deep tensions may exist between these obligations. The third part discusses the role of general rules of public international law invoked to resolve such conflicts between parallel and contradictory commitments. The article argues that, contrary to what is often argued in doctrine, the Vienna Convention on the Law of Treaties does not fully solve this conflict