Procedure — Consent to arbitration — nafta Article 1121 — Conditions precedent to submission of claim — Waiver of right to initiate or continue parallel proceedings in municipal court — Waiver implies unilateral abdication of rights — Waiver must be clear, explicit and categorical — nafta Articles 1121(3) and 1137(1)(b) — Submission of waiver in conjunction with icsid Additional Facility Rules Article 2 notice — Nature and effectiveness of waiver — Observance of formalities

Municipal law — Reliance on Mexican legislation in domestic proceedings — No express invocation of nafta breaches — Domestic proceedings fall within Article 1121 prohibition — Measures complained of in both proceedings have same factual and legal basis — Claim for breach of contract in municipal law may coexist with claim based on nafta Article 1105

Jurisdiction — Based on consent — Fulfilment of conditions precedent necessary for jurisdiction — Procedural conditions — Failure to comply with nafta Article 1121 requirements