Arbitration — North American Free Trade Agreement, Chapter 11 — UNCITRAL arbitration — Award on Merits of Phase 2 — Tribunal finding Canada in breach of Article 1105 — Canada liable to Investor for resultant damages — Effect of NAFTA Free Trade Commission’s interpretation of Article 1105

Treaties — Interpretation — North American Free Trade Agreement, Chapter 11 — Article 1105 — NAFTA Free Trade Commission issuing interpretation of Article 1105 — Commission’s interpretation issued subsequent to Award on Merits of Phase 2 — Whether Commission’s interpretation valid exercise of Commission’s power — Whether binding on arbitration tribunal — Whether operating retroactively — Validity of arbitration tribunal’s Award on Merits under Article 1105 — Whether tribunal’s interpretation of Article 1105 compatible with Commission’s interpretation — Nature and content of customary international law — Whether Canada violating Article 1105

Damages — Whether Investor entitled to damages under Article 1105 — Heads of damages — Whether recoverable — Final award on costs — Articles 38 and 40 of the UNCITRAL Arbitration Rules