Washington Revised Code Title 80. Public Utilities § 80.04.070. Inspection of books, papers, and documents

The commission and each commissioner, or any person employed by the commission, shall have the right, at any and all times, to inspect the accounts, books, papers, and documents of any public service company, and the commission, or any commissioner, may examine under oath any officer, agent, or employee of such public service company in relation thereto, and with reference to the affairs of such company: PROVIDED, That any person other than a commissioner who shall make any such demand shall produce his or her authority from the commission to make such inspection.