Title VII of the Civil Rights Act of 1964 prohibits discrimination and harassment in the workplace. In a practical sense, workplace harassment is generated by an individual — whether a co-worker, supervisor, manager, etc. There must be someone engaging in harassing conduct in order for there to be workplace harassment. And under Title VII, the status of that person affects an employer’s liability.
This makes sense. After all, if an employee is harassed at the workplace by a fellow employee and no one else ever knows about it — no supervisor, manager, or human resources personnel — the company will be in no position to take any action. For this reason, harassment promulgated by a co-worker has been judged under a general negligence standard. Only if the employer knew (or should have known) of the harassment and failed to take appropriate action can the employer be held liable. Such a rule is only fair.