Because unions have a duty of fair representation, they must treat every grievance or complaint the same and purse each all the way to arbitration, if necessary.

Duty of Fair Representation

A legal principle that requires labor unions to represent all members fairly, without bias or discrimination, in grievance and negotiation processes.

Grievance

A complaint or formal notice of dissatisfaction, usually from an employee towards an employer, regarding some aspect of employment.

Arbitration

A form of alternative dispute resolution where a neutral third party, known as an arbitrator, makes a decision to resolve a dispute outside of court.