The contract sets the route
Most collective bargaining agreements contain a grievance procedure that moves from a supervisor up through management and frequently ends in binding arbitration. Under many contracts the union, not the individual worker, decides whether a grievance goes forward, including whether it goes to arbitration. The steps carry deadlines written into the contract itself, and they can be short. Claims that depend on interpreting the agreement often have to go through that process, and a lawsuit that tries to step around it can be sent back to it. Some rights, such as protection from discrimination under statutes, exist apart from the contract, although an agreement can affect how they are pursued.
If you are a union member
Start by getting the full agreement, including side letters and memoranda that changed it, since the version posted on a wall is not always current. Keep the grievance forms, the union's responses, and the dates of every step. When a union declines to pursue a grievance, members sometimes consider a claim that the union failed in its duty of fair representation. That duty leaves a union wide room to judge which grievances are worth pressing, the claim is difficult, and its filing window is short. Most private sector workplaces fall under federal labor law and the National Labor Relations Board, while New York public employees are covered by the Taylor Law, with disputes going to the Public Employment Relations Board or, for many city workers, a local board.
If you are the employer
Management questions usually concern what the agreement actually permits: discipline under a just cause standard, changes to schedules or assignments, and how a management rights clause interacts with past practice. Changes to subjects the law treats as mandatory for bargaining generally have to be bargained, even mid-contract in many circumstances, and acting unilaterally can lead to an unfair labor practice charge. Unions are also entitled to relevant information to police the contract, and those requests deserve a careful answer. We review the agreement, how it has been applied in practice, and where any pending grievance stands before recommending a next step.