Wis. Stat. § 105.09: Visitorial power.

Any deputy may enter any employment office or the place of business of any employment agent for the purpose of collecting facts and statistics, examining the records or registers kept by the employment agent and bringing to the attention of the agent any law or any order of the department, or any failure on the part of an employment agent to comply therewith. No employment agent may refuse to admit any deputy to his or her place of business.