(1) On motion of a party, the court shall vacate an unconfirmed award if the moving party establishes that:

(a) The award was procured by corruption, fraud, or other undue means;

(b) There was:

(i) Evident partiality by the arbitrator;

(ii) Corruption by the arbitrator; or

(iii) Misconduct by the arbitrator substantially prejudicing the rights of a party;

(c) The arbitrator refused to postpone a hearing on showing of sufficient cause for postponement, refused to consider evidence material to the controversy, or otherwise conducted the hearing contrary to RCW 26.14.120, so as to prejudice substantially the rights of a party;

(d) The arbitrator exceeded the arbitrator's powers;

(e) No arbitration agreement exists, unless the moving party participated in the arbitration without making a motion under RCW 26.14.060 not later than the beginning of the first arbitration hearing; or

(f) The arbitration was conducted without proper notice under RCW 26.14.050 of the initiation of arbitration, so as to prejudice substantially the rights of a party.

(2) Except as otherwise provided in subsection (3) of this section, on motion of a party, the court shall vacate an unconfirmed award that determines a child-related dispute if the moving party establishes that:

(a) The award does not comply with RCW 26.14.140 or law of this state other than this chapter governing a child-related dispute or is contrary to the best interests of the child;

(b) The record of the hearing or the statement of reasons in the award is inadequate for the court to review the award; or

(c) A ground for vacating the award under subsection (1) of this section exists.

(3) If an award is subject to vacation under subsection (2)(a) of this section, on motion of a party, the court may amend the award if amending rather than vacating is in the best interests of the child.

(4) The court may determine a motion under subsection (2) or (3) of this section based on the record of the arbitration hearing and facts occurring after the hearing or may exercise de novo review.

(5) A motion under this section to vacate or amend an award must be filed not later than ninety days:

(a) After an arbitrator gives the party filing the motion notice of the award or a corrected award; or

(b) For a motion under subsection (1)(a) of this section, after the ground of corruption, fraud, or other undue means is known or by the exercise of reasonable care should have been known to the party filing the motion.

(6) If the court under this section vacates an award for a reason other than the absence of an enforceable arbitration agreement, the court may order a rehearing before an arbitrator. If the reason for vacating the award is that the award was procured by corruption, fraud, or other undue means or there was evident partiality, corruption, or misconduct by the arbitrator, the rehearing must be before another arbitrator.

(7) If the court under this section denies a motion to vacate or amend an award, the court may confirm the award under RCW 26.14.150 unless a motion is pending under RCW 26.14.170.