The duty of fair representation is incumbent upon Canadian[1] and U.S. labor unions that are the exclusive bargaining representative of workers in a particular group.
The concept of a DFR originated in the 1940s in the American case, Steele v. Louisville & Nashville Railroad and was formalized as a legal test in Vaca v. Sipes (1967).
A DFR wasn't enacted in statute in Canada until amendments to the Labour Relations Act of Ontario were added in 1971, followed by British Columbia in 1973.
Generally the courts have taken a deferential approach to reviewing unions' decisions challenged as a breach of their duty of fair representation.
Recognizing that the collective bargaining process typically requires compromises, which may favor some workers at the expense of others, the courts have held that a union only breaches its duty if it acts arbitrarily, in bad faith or discriminatorily.
Unlike the standard applied to unions' decisions concerning grievance handling and collective bargaining negotiations, the courts and the Board have regulated this area very extensively.
Because the Board does not usually have the jurisdiction to enforce the collective bargaining agreement or to issue a remedial order against an employer that has violated it, the NLRB often cannot award complete relief to employees.