Federal law does not prohibit "bullying," per se. It prohibits harassment where the harassment is (a) both "severe and pervasive"; and (b) based upon an employee's membership in a protected class (i.e., harassment because of the employee's race, sex, religion, etc.). If the employee's co-workers are doing the harassing, then--generally speaking--an employer only becomes legally responsible if: (a) the employee complains; and (b) the employer fails to take remedial action. It's unclear...