Wash. Rev. Code § 10.93.150
A disciplinary action or any other adverse personnel action may not be undertaken by a law enforcement agency against a peace officer solely because that officer's name has been placed on a list maintained by a prosecuting attorney's office of recurring witnesses for whom there is known potential impeachment information, or that the officer's name may otherwise be subject to disclosure pursuant to Brady v. Maryland, 373 U.S. 83 (1963). This section does not prohibit a law enforcement agency from taking disciplinary action or any other adverse personnel action against a peace officer based on the underlying acts or omissions for which that officer's name was placed on a prosecutor-maintained list, or may otherwise be subject to disclosure pursuant to Brady v. Maryland, 373 U.S. 83 (1963), if the actions taken by the law enforcement agency otherwise conform to the rules and procedures adopted by the law enforcement agency as determined through collective bargaining.
RCW 10.93.150
Intent- 2018 c 265 : "The United States supreme court has consistently found that prosecutors have the duty to disclose potentially exculpatory evidence to defense attorneys prior to trial. Some of the information that is being disclosed about government witnesses, often law enforcement officers, has not been substantiated or proven to any degree. This act prohibits a law enforcement agency from taking punitive action against a peace officer solely because the officer's name was placed on a potential impeachment list. This act specifically does not prohibit a law enforcement agency from taking punitive or personnel action against a peace officer based on the underlying acts or omissions for which that officer's name was placed on the list." [2018 c 265 s 1.]