Wash. Rev. Code § 10.46.085
When a defendant is charged with a crime which constitutes a violation of RCW 9A.64.020 or chapter 9.68, 9.68A, or 9A.44 RCW, and the alleged victim of the crime is a person under the age of eighteen years, neither the defendant nor the prosecuting attorney may agree to extend the originally scheduled trial date unless the court within its discretion finds that there are substantial and compelling reasons for a continuance of the trial date and that the benefit of the postponement outweighs the detriment to the victim. The court may consider the testimony of lay witnesses and of expert witnesses, if available, regarding the impact of the continuance on the victim.
RCW 10.46.085
Finding-1989 c 332: "The legislature finds that treatment of the emotional problems of child sexual abuse victims may be impaired by lengthy delay in trial of the accused and the resulting delay in testimony of the child victim. The trauma of the abusive incident is likely to be exacerbated by requiring testimony from a victim who has substantially completed therapy and is forced to relive the incident. The legislature finds that it is necessary to prevent, to the extent reasonably possible, lengthy and unnecessary delays in trial of a person charged with abuse of a minor." [ 1989 c 332 s 6.]