171 Opinion of the Court. in the labor relations area and the desirability of leaving the development of such rules to the administrative agency created by Congress for that purpose-is not applicable to cases involving alleged breaches of the union's duty of fair representation. The doctrine was judicially developed in Steele and its progeny, and suits alleging breach of the duty remained judicially cognizable long after the NLRB was given unfair labor practice jurisdiction over union activities by the L. M. R. A. Moreover, when the Board declared in Miranda Fuel that a union's breach of its duty of fair representation would henceforth be treated as an unfair labor practice, the Board adopted and applied the doctrine as it had been developed by the federal courts. See 140 N. L. R. B., at 184-186. Finally, as the dissenting Board members in Miranda Fuel have pointed out, fair representation duty suits often require review of the substantive positions taken and policies pursued by a union in its negotiation of a collective bargaining agreement and in its handling of the grievance machinery; as these matters are not normally within the Board's unfair labor practice jurisdiction, it can be doubted whether the Board brings substantially greater expertise to bear on these problems than do the courts, which have been engaged in this type of review since the Steele decision." In addition to the above considerations, the unique interests served by the duty of fair representation doc 6 See Ford Motor Co. v. Huffman, 345 U. S. 330, 332, n. 4. In Huffman, the NLRB submitted an amicus brief stating that it had not assumed pre-emptive jurisdiction over fair representation duty issues. Mem. for the NLRB, Nos. 193 and 194, Oct. Term, 1952. In Syres v. Oil Workers International Union, 350 U. S. 892, the Court reversed the dismissal of a suit which claimed breach of the duty of fair representation despite express reliance by one respondent on exclusive NLRB jurisdiction. Brief for Resp. Gulf Oil Corp., No. 390, Oct. Term, 1955. See Hughes Tool Co., 147 N. L. R. B. 1573, 1589-1590 (Chairman McCulloch and Member Fanning, dissenting in part). Opinion of the Court. 386 U.S. trine have a profound effect, in our opinion, on the applicability of the pre-emption rule to this class of cases. The federal labor laws seek to promote industrial peace and the improvement of wages and working conditions by fostering a system of employee organization and collective bargaining. See N. L. R. A. § 1, as amended, 61 Stat. 136, 29 U. S. C. § 151. The collective bargaining system as encouraged by Congress and administered by the NLRB of necessity subordinates the interests of an individual employee to the collective interests of all employees in a bargaining unit. See, e. g., J. I. Case Co. v. Labor Board, 321 U. S. 332. This Court recognized in Steele that the congressional grant of power to a union to act as exclusive collective bargaining representative, with its corresponding reduction in the individual rights of the employees so represented, would raise grave constitutional problems if unions were free to exercise this power to further racial discrimination. 323 U. S., at 198-199. Since that landmark decision, the duty of fair representation has stood as a bulwark to prevent arbitrary union conduct against individuals stripped of traditional forms of redress by the provisions of federal labor law. Were we to hold, as petitioners and the Government urge, that the courts are foreclosed by the NLRB's Miranda Fuel decision from this traditional supervisory jurisdiction, the individual employee injured by arbitrary or discriminatory union conduct could no longer be assured of impartial review of his complaint, since the Board's General Counsel has unreviewable discretion to refuse to institute an unfair labor practice complaint. See United Electrical Contractors Assn. v. Ordman, 366 F. 2d 776, cert. denied, 385 U. S. 1026.8 The existence of even a small group 8 The public interest in effectuating the policies of the federal labor laws, not the wrong done the individual employee, is always the Board's principal concern in fashioning unfair labor practice remedies. See N. L. R. A. § 10 (c), as amended, 61 Stat. 147, 29 U. S. C. 171 Opinion of the Court. of cases in which the Board would be unwilling or unable to remedy a union's breach of duty would frustrate the basic purposes underlying the duty of fair representation doctrine. For these reasons, we cannot assume from the NLRB's tardy assumption of jurisdiction in these cases that Congress, when it enacted N. L. R. A. § 8 (b) in 1947, intended to oust the courts of their traditional jurisdiction to curb arbitrary conduct by the individual employee's statutory representative. B. There are also some intensely practical considerations which foreclose pre-emption of judicial cognizance of fair representation duty suits, considerations which emerge from the intricate relationship between the duty of fair representation and the enforcement of collective bargaining contracts. For the fact is that the question of whether a union has breached its duty of fair representation will in many cases be a critical issue in a suit under L. M. R. A. § 301 charging an employer with a breach of contract. To illustrate, let us assume a collective bargaining agreement that limits discharges to those for good cause and that contains no grievance, arbitration or other provisions purporting to restrict access to the courts. If an employee is discharged without cause, either the union or the employee may sue the employer under L. M. R. A. § 301. Under this section, courts have jurisdiction over suits to enforce collective bargaining agreements even though the conduct of the employer which is challenged as a breach of contract is also arguably an unfair labor practice within the jurisdiction of § 160 (c); Phelps Dodge Corp. v. Labor Board, 313 U. S. 177. Thus, the General Counsel will refuse to bring complaints on behalf of injured employees where the injury complained of is "insubstantial." See Administrative Decision of the General Counsel, Case No. K-610, Aug. 13, 1956, in CCH N. L. R. B. Decisions, 1956-1957, Transfer Binder, 54,059. Opinion of the Court. 386 U.S. the NLRB. Garmon and like cases have no application to § 301 suits. Smith v. Evening News Assn., 371 U. S. 195. The rule is the same with regard to pre-emption where the bargaining agreement contains grievance and arbitration provisions which are intended to provide the exclusive remedy for breach of contract claims. If an employee is discharged without cause in violation of such an agreement, that the employer's conduct may be an unfair labor practice does not preclude a suit by the union 10 against the employer to compel arbitration of the employee's grievance, the adjudication of the claim by the arbitrator, or a suit to enforce the resulting arbitration award. See, e. g., Steelworkers v. American Mfg. Co., 363 U. S. 564. However, if the wrongfully discharged employee himself resorts to the courts before the grievance procedures have been fully exhausted, the employer may well defend on the ground that the exclusive remedies provided by such a contract have not been exhausted. Since the employee's claim is based upon breach of the collective bargaining agreement, he is bound by terms of that agreement which govern the manner in which contractual rights may be enforced. For this reason, it is settled that the employee must at least attempt to exhaust exclusive grievance and arbitration procedures established by the bargaining agreement. Republic Steel Corp. v. Maddox, 379 U. S. If a grievance and arbitration procedure is included in the contract, but the parties do not intend it to be an exclusive remedy, then a suit for breach of contract will normally be heard even though such procedures have not been exhausted. See Republic Steel Corp. v. Maddox, 379 U. S. 650, 657-658; 6A Corbin, Contracts § 1436 (1962). 10 Occasionally, the bargaining agreement will give the aggrieved employee, rather than his union, the right to invoke arbitration. See Retail Clerks v. Lion Dry Goods, Inc., 341 F. 2d 715, cert. denied, 382 U. S. 839. 171 Opinion of the Court. 650. However, because these contractual remedies have been devised and are often controlled by the union and the employer, they may well prove unsatisfactory or unworkable for the individual grievant. The problem then is to determine under what circumstances the individual employee may obtain judicial review of his breachof-contract claim despite his failure to secure relief through the contractual remedial procedures. An obvious situation in which the employee should not be limited to the exclusive remedial procedures established by the contract occurs when the conduct of the employer amounts to a repudiation of those contractual procedures. Cf. Drake Bakeries v. Bakery Workers, 370 U. S. 254, 260-263. See generally 6A Corbin, Contracts § 1443 (1962). In such a situation (and there may of course be others), the employer is estopped by his own conduct to rely on the unexhausted grievance and arbitration procedures as a defense to the employee's cause of action. We think that another situation when the employee may seek judicial enforcement of his contractual rights arises if, as is true here, the union has sole power under the contract to invoke the higher stages of the grievance procedure, and if, as is alleged here, the employee-plaintiff has been prevented from exhausting his contractual remedies by the union's wrongful refusal to process the grievance. It is true that the employer in such a situation may have done nothing to prevent exhaustion of the exclusive contractual remedies to which he agreed in the collective bargaining agreement. But the employer has committed a wrongful discharge in breach of that agreement, a breach which could be remedied through the grievance process to the employee-plaintiff's benefit were it not for the union's breach of its statutory duty of fair representation to the employee. To leave the employee remediless in such circumstances would, in our |