Wash. Rev. Code § 41.56.220
Any public employee who represents fifty percent or more of a bargaining unit or who represents on a statewide basis a group of five or more bargaining units shall have the right to absent himself or herself from his or her employment without pay and without suffering any discrimination in his or her future employment and without losing benefits incident to his or her employment while representing his or her bargaining unit at the legislature of the state of Washington during any regular or special session thereof: PROVIDED, That such employee is replaced by his or her bargaining unit with an employee who shall be paid by the employer and who shall be qualified to perform the duties and obligations of the absent member in accordance with the rules of the civil service or other standards established by his or her employer for such absent employee.
RCW 41.56.220