Wis. Stat. § 885.15: Immunity.

(1) No person may be excused from attending, testifying or producing books, papers, and documents before any court in a prosecution under s. 134.05 on the ground or for the reason that the testimony or evidence required of him or her may tend to incriminate him or her, or to subject him or her to a penalty or forfeiture. No person who testifies or produces evidence in obedience to the command of the court in the prosecution may be liable to any suit or prosecution, civil or criminal, for or on account of testifying or producing evidence; provided, that no person may be exempted from prosecution and punishment for perjury committed in so testifying.

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