(5) A decision on a matter entrusted by paragraph (3) or (4) of this article to the court or other authority specified in article 6 shall be subject to no appeal. The court or other authority, in appointing an arbitrator, shall have due regard to any qualifications required of the arbitrator by the agreement of the parties and to such considerations as are likely to secure the appointment of an independent and impartial arbitrator and, in the case of a sole or third arbitrator, shall take into account as well the advisability of appointing an arbitrator of a nationality other than those of the parties.
[Note: See section 24.]
Article 12. Grounds for challenge
(1) When a person is approached in connection with his possible appointment as an arbitrator, he shall disclose any circumstances likely to give rise to justifiable doubts as to his impartiality or independence. An arbitrator, from the time of his appointment and throughout the arbitral proceedings, shall without delay disclose any such circumstances to the parties unless they have already been informed of them by him.
(2) An arbitrator may be challenged only if circumstances exist that give rise to justifiable doubts as to his impartiality or independence, or if he does not possess qualifications agreed to by the parties. A party may challenge an arbitrator appointed by him, or in whose appointment he has participated, only for reasons of which he becomes aware after the appointment has been made.
[Note: See section 25.]
Article 13. Challenge procedure
(1) The parties are free to agree on a procedure for challenging an arbitrator, subject to the provisions of paragraph (3) of this article.
(2) Failing such agreement, a party who intends to challenge an arbitrator shall, within fifteen days after becoming aware of the constitution of the arbitral tribunal or after becoming aware of any circumstance referred to in article 12(2), send a written statement of the reasons for the challenge to the arbitral tribunal. Unless the challenged arbitrator withdraws from his office or the other party agrees to the challenge, the arbitral tribunal shall decide on the challenge.
