(1) The commission and the attorney for a party may issue subpoenas according to the requirements of RCW 34.05.446. Unrepresented (pro se) parties may request the presiding officer to issue for them such subpoenas as are necessary to enable them to fairly present their case. Every subpoena must:

(a) State the name of the commission; and

(b) State the title of the adjudicative proceeding; and

(c) Command the persons to whom they are addressed to attend and give testimony, produce books, records, documents, or things under their control at a specified time and place.

(2) All parties must serve their subpoenas on all other parties at least ten days before the specified time for appearance or document production.

(3) Any person eighteen years of age or older may serve subpoenas by showing and reading the subpoenas to witnesses, or by giving them a copy of the subpoena, or by leaving a copy at their residence.

(4) When anyone other than an officer authorized to serve process performs service, the server must make proof of service by affidavit or a declaration under penalty of perjury.

(5) If a party makes a motion at or before the time stated for compliance in the subpoena, the presiding officer may:

(a) Quash or modify an unreasonable and oppressive subpoena; or

(b) Order the person who issued the subpoena to pay the reasonable cost of producing the books, papers, documents, or tangible things.

(6) Parties may seek judicial enforcement of subpoenas under RCW 34.05.588.

(7) Witnesses must attend and provide requested testimony or documents at the specified time and place.

(8) During a hearing, if it appears in the public interest or in the interest of justice that further testimony or argument should be received, the presiding officer may at his or her discretion continue the hearing and:

(a) Set the hearing ahead to a certain date; and

(b) Subpoena, or allow a party to subpoena, additional argument or evidence.