Washington Revised Code Title 11. Probate and Trust Law § 11.90.060. Testimony and documentary evidence from another state

(1) In a guardianship or protective proceeding, in addition to other procedures that may be available, testimony of a witness who is located in another state may be offered by deposition or other means allowable in this state for testimony taken in another state.  The court on its own motion may order that the testimony of a witness be taken in another state and may prescribe the manner in which and the terms upon which the testimony is to be taken.

(2) In a guardianship or protective proceeding, a court in this state may permit a witness located in another state to be deposed or to testify by telephone or audiovisual or other electronic means.  A court of this state shall cooperate with the court of the other state in designating an appropriate location for the deposition or testimony.

(3) Documentary evidence transmitted from another state to a court of this state by technological means that do not produce an original writing may not be excluded from evidence on an objection based on the best evidence rule.