What are the union's obligations under a typical union contract?

Under a typical union contract, the union is obligated to live up to the terms of the entire contract. In particular, the union usually gives up the right to strike during the life of the contract in exchange for final and binding arbitration. Unions can be sued for violating a collective bargaining agreement. Unions also have a duty of fair representation that requires them to fairly and without discrimination represent all bargaining unit members.