At a time when labor peace is their stated goal, club owners have dismissed baseball’s impartial arbitrator, George Nicolau, who held the position twice as long as any of his predecessors and ruled in landmark collusion and drug cases.

John Westhoff, a lawyer with the Player Relations Committee, notified Nicolau in a letter dated last Wednesday that the clubs were exercising their rights under the collective bargaining agreement and firing him after nine years on the job.