The following definitions are applicable in this chapter unless the context otherwise requires:
(1) "Materially false statement" means any false statement oral or written, regardless of its admissibility under the rules of evidence, which could have affected the course or outcome of the proceeding;
(2) "Oath" includes an affirmation and every other mode authorized by law of attesting to the truth of that which is stated; in this chapter, written statements shall be treated as if made under oath if:
(a) The statement was made on or pursuant to instructions on an official form bearing notice, authorized by law, to the effect that false statements made therein are punishable;
(b) The statement recites that it was made under oath, the declarant was aware of such recitation at the time he or she made the statement, intended that the statement should be represented as a sworn statement, and the statement was in fact so represented by its delivery or utterance with the signed jurat of an officer authorized to administer oaths appended thereto; or
(c) It is a statement, declaration, verification, or certificate, made within or outside the state of Washington, which is declared to be true under penalty of perjury as provided in chapter
5.50 RCW.
(3) An oath is "required or authorized by law" when the use of the oath is specifically provided for by statute or regulatory provision or when the oath is administered by a person authorized by state or federal law to administer oaths;
(4) "Official proceeding" means a proceeding heard before any legislative, judicial, administrative, or other government agency or official authorized to hear evidence under oath, including any referee, hearing examiner, commissioner, notary, or other person taking testimony or depositions;
(5) "Juror" means any person who is a member of any jury, including a grand jury, impaneled by any court of this state or by any public servant authorized by law to impanel a jury; the term juror also includes any person who has been drawn or summoned to attend as a prospective juror;
(6) "Testimony" includes oral or written statements, documents, or any other material that may be offered by a witness in an official proceeding.