Wis. Stat. § 346.73: Accident reports not to be used in trial.

Notwithstanding s. 346.70 (4) (f), accident reports required to be filed with or transmitted to the department or a county or municipal authority shall not be used as evidence in any judicial trial, civil or criminal, arising out of an accident, except that such reports may be used as evidence in any administrative proceeding conducted by the department. The department shall furnish upon demand of any person who has or claims to have made such a report, or upon demand of any court, a certificate showing that a specified accident report has or has not been made to the department solely to prove a compliance or a failure to comply with the requirement that such a report be made to the department.