In Wisconsin Bell, Inc. v. Labor and Industry Review Commission and Charles Carlson (Carlson), the Wisconsin Supreme Court stated that employees who claim disability discrimination must prove discriminatory intent or that the employer knew the employee’s misconduct or poor performance was caused by a disability.

There, Carlson suffered from bipolar I disorder and was disciplined for customer mistreatment and avoiding his job duties. While awaiting final discipline, he presented doctor letters regarding his disability. After a final warning was issued, Carlson again avoided his job duties and claimed he needed to leave work for illness, but did not specify his disorder. His computer activity during this time suggested he was not actually ill. Again, while awaiting final discipline, he presented doctor’s letters regarding his disability. Ultimately, Carlson was terminated for policy violations.

The Wisconsin Supreme Court stated that the employee must show that the employer’s decision at the time was based on its knowledge of a causal connection between the employee’s misconduct and the disability. The court stated that the doctor’s letters presented by Carlson did not notify the employer of a connection between his disability and his behavior at work, and therefore the discipline was not unlawful.