Wash. Rev. Code § 29A.68.050
The clerk shall issue subpoenas for witnesses in such contested election at the request of either party, which shall be served by the sheriff or constable, as other subpoenas, and the superior court shall have full power to issue attachments to compel the attendance of witnesses who shall have been duly subpoenaed to attend if they fail to do so.
The court shall meet at the time and place designated to determine such contested election by the rules of law and evidence governing the determination of questions of law and fact, so far as the same may be applicable, and may dismiss the proceedings if the statement of the cause or causes of contest is insufficient, or for want of prosecution. After hearing the proofs and allegations of the parties, the court shall pronounce judgment in the premises, either confirming or annulling and setting aside such election, according to the law and right of the case.
If in any such case it shall appear that another person than the one returned has the highest number of legal votes, said court shall declare such person duly elected. If in any such case it shall appear that the results of a measure are reversed, said court shall declare the change in result.
RCW 29A.68.050