Under the NLRB, a union that is your exclusive representative with your employer owes a duty of fair representation to employees in the bargaining unit, which means that it must treat all bargaining members fairly and equally in representing them before the employer. This duty arises when you have an individual dispute with your employer, such as a disciplinary matter or termination, and may be violated if the exclusive bargaining representative (the union) fails to properly represent you in that dispute.
If the union refuses to get involved to protect your rights as guaranteed by the union contract, you may be able to file a claim against the union for violating your duty of fair representation, also known as a DFR claim. However, not every situation where you are unhappy with the union's representation gives rise to a DFR claim. You must prove that the union acted in an arbitrary manner and/or in bad faith - mere negligence or ineptitude does not count. Some factors to be considered are:
Whether the union can rationally explain its conduct;
Whether the situation left you with no venue to obtain a hearing/remedy for the underlying dispute; and
Whether the union followed or deviated from its past practices in the manner in which it processed the dispute and dealt with you personally.
The duty of fair representation does not require your union to file a grievance on your behalf, take your grievance to arbitration, or appeal it every step of the way, if it feels your grievance does not have merit.
If you have a DFR claim, you can either sue the union directly in court, or can file a claim with the NLRB. Either way, you must file your DFR claim within six months of the union activity which you claim violated your duty of fair representation. Check with your local NLRB office, or a private attorney who has expertise in working with labor issues, for more information to help you determine whether you may be able to bring a DFR case.