An employe cannot recover punitive from a union that breaches its duty to provide him with fair representation, the Supreme Court ruled yesterday.

The justices agreed 9 to 0 on the narrow issue in the case: The Railway Labor Act bars recovery of such damages, which are "private fines" levied by civil juries to punish, and deter repetition of, reprehensible conduct.

But four of them protested that the majority, in an opinion by Justice Thurgood Marshall, was laying down a blanket rule of union immunity to punitive damages no matter how egregious the breach of duty may be.

The case grew out of an on-the-job injury suffered by Leroy Foust, an employe of the Union Pacific Railroad Co. and a member of the International Brotherhood of Electrical Workers.

He took a medical leave and then sought an extension, but somehow failed to supply a doctor's statement within the time period provided in the collective bargaining agreement. Nine days after Union Pacific assured Foust that it would delay action until he obtained the statement, it fired him.

Foust asked the union to start a grievance proceeding, but the IBEW failed to write the necessary letter to the company until two days after the expiration of the 60-day filing deadline specified in the contract. Backed by the National Railroad Adjustment Board, Union Pacific refused to accept Foust's claim of wrongful discharge because of the union's tardiness in grieving.

Foust then sued the IBEW and several of its officers, charging that by being late in filing the grievance letter they had caused the company to dismiss his claim.

A jury in Wyoming awarded him $40,000 actual and $75,000 punitive damages.The 10th U.S. Circuit Court of Appeals, while sending the case back to see of the punitive damages were excessive, nonetheless held that such damages could be awarded. This brought it into conflict with other circuits.

The Supreme Court reversed. Punitive damages are impermissible against unions that fail to provide fair representation of their members on pursuing grievances because, Marshall wrote, "general labor policy disfavors punishment, and the adverse consequences of punitive damage awards could be substantial."

Justice Harry A. Blackmun wrote the separate opinion concurring in the judgement in Foust's case but rejecting the broad rule. His opinion was signed by Chief Justice Warren E. Burger and Justices William H. Rehnquist and John Paul Stevens.