This is from the panel request in DS429:
Because the United States has acted in the manner just described, Viet Nam considers the proceedings to be inconsistent, as such and as applied on a continued and ongoing basis, with certain WTO obligations. Viet Nam considers these actions to be inconsistent with the following provisions of the Anti-Dumping Agreement and the Vienna Convention on the Law of Treaties:
...
6. Article 31 of the Vienna Convention on the Law of Treaties because the USDOC's practice does not comport with the overall purpose and intent of the Anti-Dumping Agreement, namely, the fair and effective imposition of anti-dumping duties so as to prevent the sale of goods for less than fair value.
A WTO claim based on the VCLT?? Wow, this could really push the boundaries of the role of international law in WTO law.
Alas, it was not to be. This is how the issue was dealt with in the panel report (p. A-16):
4 US PRELIMINARY OBJECTION WITH RESPECT TO VIET NAM'S CLAIM UNDER ARTICLE 31 OF THE VIENNA CONVENTION
4.1. Viet Nam's panel request sets forth a claim with respect to the USDOC's limitation of the number of respondents selected for full investigation or review under, inter alia, Article 31 of the Vienna Convention on the Law of Treaties because the USDOC's practice does not comport with the overall purpose and intent of the Anti-Dumping Agreement, namely, the fair and effective imposition of anti-dumping duties so as to prevent the sale of goods for less than fair value.
4.2. The United States requests that the Panel find that this claim does not fall within its terms of reference. The United States argues that the Vienna Convention is not a "covered agreement" as defined in the DSU. Viet Nam indicates that it did not and does not intend to assert a claim under the Vienna Convention.
4.3. In light of this clarification, we do not consider it necessary to rule on this aspect of the United States' request for preliminary rulings.
