Wash. Rev. Code § 5.64.010
Civil actions against health care providers—Admissibility of evidence of furnishing or offering to pay medical expenses—Admissibility of expressions of apology, sympathy, fault, etc
(1) In any civil action against a health care provider for personal injuries which is based upon alleged professional negligence, or in any arbitration or mediation proceeding related to such civil action, evidence of furnishing or offering or promising to pay medical, hospital, or similar expenses occasioned by an inj…