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 arbitrators impartiality or independence, or if the arbitrator does not possess qualifications agreed to by the parties. A party may challenge the arbitrator appointed by him only for reasons of which he becomes aware after the appointment has been made.

Article 13. Challenge procedure

1. The parties are free to agree on a procedure for challenging an arbitrator, subject to the provision of paragraph (3) of this article
2. Failing such agreement, a party who intends to challenge an arbitrator shall, within 15 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.
3. If a challenge under any procedure agreed upon by the parties or under the procedure of paragraph (2) of this article is not successful, the challenging party may request, within thirty days after having received notice of the decision rejecting the challenge, the court or other authority specified in article 6 on the challenge, which decision shall be subject to no appeal; while such a request is pending, the arbitral tribunal, including the challenged arbitrator, may continue the arbitral proceeding and make an award.

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