Washington § 7.05.340 - Statement of claim and defense.

(1) Within the period of time agreed by the parties or determined by the arbitral tribunal, the claimant shall state the facts supporting its claim, the point at issue, and the relief or remedy sought, and the respondent shall state its defense in respect of these particulars, unless the parties have otherwise agreed as to the required elements of such statements. The parties may submit with their statements all documents they consider to be relevant or may add a reference to the documents or other evidence they will submit.

(2) Unless otherwise agreed by the parties, either party may amend or supplement its claims or defenses during the course of the arbitral proceedings, unless the arbitral tribunal considers it inappropriate to allow such amendment having regard to the delay in making it.