Wis. Stat. § 194.31: Inspection of records.

The secretary, or any person employed by the secretary, shall, upon demand, have the right to inspect the insurance records of any common motor carrier of property or of passengers or of any contract motor carrier and to examine under oath any officer, agent or employee of such carrier in relation to the insurance required under s. 194.41; provided that any person other than the secretary who shall make such demand shall produce his or her authority under the hand and seal of the department.