Duty of fair representation is the legal duty of a union to equally, and in good faith, represent every employee in a bargaining unit, regardless of whether the employee is a union member or not. This legal duty arises out of the exclusive representative status unions hold under the National Labor Relations Act. A breach of the statutory duty of fair representation occurs only when a union's conduct toward a member of the collective bargaining unit is arbitrary, discriminatory, or in bad faith.
The duty of fair representation requires that a union represent all workers equally and without prejudice. A union cannot refuse to represent or improperly represent a worker due to the worker’s age, race, creed, nationality, sex, religion, political beliefs, union status or personality. If a union fails to represent a worker due to prejudice or hostility the union can be held liable. Its purpose is to ensure that the course of action in any grievance case will be determined by the merits of the grievance, and not by the merits of the grievant. The union may refuse to file or process a grievance for any number of reasons so long as they are valid, however it may not arbitrarily refuse to process a meritorious grievance or decline to proceed to arbitration because of hostility to the grievant or irrelevant and ill-motivated reasons.