Wis. Stat. § 102.58: Decreased compensation.

(1) If injury is caused by the failure of the employee to use safety devices that are provided in accordance with any statute, rule, or order of the department of safety and professional services and that are adequately maintained, and the use of which is reasonably enforced by the employer, or if injury results from the employee’s failure to obey any reasonable rule adopted and reasonably enforced by the employer for the safety of the employee and of which the employee has notice, the compensation and death benefit provided in this chapter shall be reduced by 15 percent, but the total reduction may not exceed $15,000.

(2) If an employee violates the employer’s policy concerning employee drug or alcohol use and is injured, and if that violation is causal to the employee’s injury, no compensation or death benefits shall be payable to the injured employee or a dependent of the injured employee and no payment under s. 102.49 (5) (b) or (c) shall be payable. Nothing in this subsection shall reduce or eliminate an employer’s liability for incidental compensation under s. 102.42 (1) to (8) or drug treatment under s. 102.425.