I. INTRODUCTION 

1. The Article 1128 submissions of the United States and Mexico confirm that all three NAFTA Parties are in agreement – the Bilcon tribunal was incorrect in its interpretations of NAFTA Article 1102 (National Treatment) and Article 1105 (Minimum Standard of Treatment). This unanimous agreement reflects an authoritative interpretation of the NAFTA that must be taken into account by this Tribunal in accordance with Article 31 of the Vienna Convention on the Law of Treaties (“Vienna Convention”). 

2. In particular, the NAFTA Parties agree that: (i) the burden of proving a rule of customary international law under NAFTA Article 1105 rests solely on the claimant and requires proof of both State practice and opinio juris; (ii) the awards of investment tribunals do not qualify as state practice for the purposes of proving the existence of a rule of customary international law; (iii) a Chapter 11 tribunal does not have the jurisdiction to determine whether a challenged measure is consistent with domestic law; (iv) a breach of domestic law is not in and of itself a breach of Article 1105; (v) NAFTA Article 1102 only prohibits differential treatment on the basis of nationality; and (vi) the burden of proof with respect to Article 1102 rests and remains solely with the Claimant.