Wash. Rev. Code § 51.36.100
The legislature finds and declares it to be in the public interest of the residents of the state of Washington that a proper regulatory and inspection program be instituted in connection with the provision of medical, chiropractic, dental, vocational, and other health services to industrially injured workers pursuant to Title 51 RCW. In order to effectively accomplish such purpose and to assure that the industrially injured worker receives such services as are paid for by the state of Washington, the acceptance by the industrially injured worker of such services, and the request by a provider of services for reimbursement for providing such services, shall authorize the director of the department of labor and industries or the director's authorized representative to inspect and audit all records in connection with the provision of such services.
RCW 51.36.100