If the NMB determines further mediation will not bring the parties to agreement, the agency will urge the parties to accept binding arbitration to resolve their bargaining disputes. Either party is free to reject arbitration, but if both parties accept, an arbitration board will issue a final and binding decision regarding the terms of the parties’ agreement. If either or both parties reject arbitration, the NMB will release them from the mediation process and into a 30-day cooling off period.