Wis. Stat. § 111.62
It shall be unlawful for any group of employees of a public utility employer acting in concert to call a strike or to go out on strike, or to cause any work stoppage or slowdown which would cause an interruption of an essential service; it also shall be unlawful for any public utility employer to lock out the employer's employees when such action would cause an interruption of essential service; and it shall be unlawful for any person or persons to instigate, to induce, to conspire with, or to encourage any other person or persons to engage in any strike or lockout or slowdown or work stoppage which would cause an interruption of an essential service. Any violation of this section by any member of a group of employees acting in concert or by any employer or by any officer of an employer acting for such employer, or by any other individual, shall constitute a misdemeanor.
Wis. Stat. § 111.62