Arbitrators are appointed to resolve grievance disputes between unions and employers. All collective agreements governed by Part I (Industrial Relations) of the Canada Labour Code must contain a provision for the final settlement, without work stoppage, of any differences which relate to the interpretation, application, administration or alleged violation of the agreement. This usually involves referral of the grievance to arbitration. If parties are unable to agree on the choice of an arbitrator or the chairperson of an arbitration board, the Minister of Labour may be asked to make the appointment. In such cases, the parties remain responsible for payment of the arbitrator's fees and expenses.