(2) Failing any agreement referred to in subsection (1) of this section, a party which 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 circumstances referred to in ORS 36.476 (4) and (5), whichever shall be later, send a written statement of the reasons for the challenge to the arbitral tribunal.

(3) Unless the arbitrator challenged under subsection (2) of this section withdraws from office or the other party agrees to the challenge, the arbitral tribunal shall decide the challenge.

(4)(a) If a challenge under any procedure agreed upon by the parties or under the procedure under subsections (2) and (3) of this section is not successful, the challenging party may request the circuit court, within 30 days after having received notice of the decision rejecting the challenge, to decide on the challenge.

(b) When the request is made, the circuit court may refuse to decide on the challenge if it is satisfied that, under the procedure agreed upon by the parties, the party making the request had an opportunity to have the challenge decided upon by other than the arbitral tribunal.

(c) Notwithstanding paragraph (b) of this subsection, whether the challenge is under any procedure agreed upon by the parties or under the procedure under subsections (2) and (3) of this section, if a challenge is based upon the grounds set forth in ORS 36.476 (1), the circuit court shall hear the challenge and, if it determines that the facts support a finding that such ground or grounds fairly exist, then the challenge shall be sustained.

(5) The decision of the circuit court under subsection (4) of this section is final and not subject to appeal.

(6) While a request under subsection (4) of this section is pending, the arbitral tribunal, including the challenged arbitrator, may continue with the arbitral proceedings and make an arbitral award. [1991 c.405 §16; 1993 c.244 §4]