Does an employee have to exhaust all their contractual remedies?

Under the case law, however, there exists an important exception to the requirement that the employee exhaust his contractual remedies. An employee may escape a defense based on his failure to exhaust, as well as avoid the exclusive nature of the contract remedies, "provided the employee can prove that the union as bargaining agent breached its duty of fair representation in its handling of the employee's grievance." Vaca v. Sipes, supra, 386 U.S. at 186, 87 S.Ct. at 914. Accord, Clayton v. ITT Gilfillan, supra, 623 F.2d at 568.