Arbitrators — Composition of tribunal — Challenge to President of ad hoc Committee — Procedure for challenging members of ad hoc Committee — ICSID Convention, Article 53(4) — Validity of Arbitration Rule 53

Arbitrators — Composition of tribunal — Challenge to President of ad hoc Committee — Connection between President’s law firm and related company of Claimant — No personal involvement of President — No general retainer — Partner’s legal advice on matters unrelated to dispute before the Committee — Work substantially complete before commencement of proceedings — De minimis rule — Challenge rejected

Jurisdiction — Relation between concession contract, bilateral investment treaty and icsid Convention — Dispute with provincial authorities relating to investment contract — Investment contract providing for exclusive jurisdiction of provincial courts — Whether precluding claim under treaty

Jurisdiction — State responsibility claim against Argentina arising from conduct of provincial authorities — Non-designation of province under icsid, Article 25 — Article 25 irrelevant to treaty claim

Treaties — Bilateral investment treaty — Argentina–France bilateral investment treaty, Article 8(2) — “Fork in the road” provision — Relevance to Tribunal’s jurisdiction over treaty claim — Relevance to merits of claim

Annulment — Annulment proceedings — Claimant seeking partial annulment of decision on merits — Respondent seeking in the alternative annulment of whole award — Admissibility of Respondent’s claim — Whether a “counterclaim” — Power of ad hoc Committee to determine extent of annulment — Respondent’s arguments admissible

Annulment — Annulment proceedings — Tribunal finding that federal authorities did not fail to assist in resolution of provincial claim — No basis for annulment — icsid Convention, Article 53

Annulment — Annulment proceedings — State responsibility — Tribunal finding that it could not determine whether there was a treaty breach prior to municipal court proceedings on the contract claim — Bilateral investment treaty excluding requirement of exhaustion of local remedies — Manifest excess of jurisdiction — Failure to give reasons — Relation of treaty claim to contract claim — icsid Convention, Articles 26, 53 — ilc Articles on Responsibility of States for Internationally Wrongful Acts, 2001, Article 3