They feel treated like dirt. Workers call lawyers when they feel wronged in some way, especially when they have been treated less than humanely. Toxic workplaces or Toxic Managers lead to lawsuits.
A manager has gone rogue. Managers who harass a subordinate or terminate an employee because he/she got a serious illness. Typically the employer knew the manager was a problem and allowed the behavior to continue. In these situations jurors are not kind to employers.
Rules aren’t enforced evenly. Employees think the law is being broken when one employee is punished for breaking rules and another isn’t.