concurring.
I agree with the Court that proof of breach of the Union’s duty of fair representation will remove the bar of finality from the arbitral decision that Anchor did not wrongfully discharge the petitioners. See Vaca v. Sipes, 386 U. S. 171, 194; Humphrey v. Moore, 375 U. S. 335, 348-351. But this is not to say that proof of breach of the Union’s representation duty would render Anchor potentially liable for backpay accruing between the time of the “tainted” decision by the arbitration committee *573and a subsequent “untainted” determination that the discharges were, after all, wrongful.
If an employer relies in good faith on a favorable arbitral decision, then his failure to reinstate discharged employees cannot be anything but rightful, until there is a contrary determination. Liability for the intervening wage loss must fall not on the employer but on the union. Such an apportionment of damages is mandated by Vaca’s holding that “damages attributable solely to the employer’s breach of contract should not be charged to the union, but increases if any in those damages caused by the union’s refusal to process the grievance should not be charged to the employer.” 386 U. S., at 197-198. To hold an employer liable for back wages for the period during which he rightfully refuses to rehire discharged employees would be to charge him with a contractual violation on the basis of conduct precisely in accord with the dictates of the collective agreement.