Wis. Stat. § 139.20: Compulsory testimony.

(1) Any person may be compelled to testify in regard to any violation of this chapter of which the person may have knowledge, even though such testimony may tend to incriminate the person, upon being granted immunity from prosecution in connection therewith, and upon the giving of such testimony, such person shall not be prosecuted for or because of the violation relative to which the person has testified.

(2) The immunity provided under sub. (1) is subject to the restrictions under s. 972.085.