Wash. Rev. Code § 4.24.495
(2) Public employers and an employee organization, or any of their employees or agents, are not liable for, and have a complete defense to, any claims or actions under the law of this state for requiring, deducting, receiving, or retaining agency or fair share fees from public employees, and current or former public employees do not have standing to pursue these claims or actions, if the fees were permitted at the time under the laws of this state then in force and paid, through payroll deduction or otherwise, before June 27, 2018.
(4) For purposes of this section:
[ 2019 c 230 s 1.]