BATH, Maine — A federal judge has dismissed a lawsuit filed by the largest union at Bath Iron Works charging an arbitrator in a high-profile grievance with ruling in favor of the shipyard’s management as a way of removing himself from the company’s “strike list.”

Local S6 of the machinists union filed suit in May against BIW, alleging arbitrator James S. Cooper showed “sufficient partiality” when he ruled in February that the company did not violate the existing contract by outsourcing work, according to documents filed in U.S. District Court.

The union alleged that during a September 2015 meeting with Local S6 President Richard Nolon and company representative Dana McIntire, Cooper said “that he had gone six years without hearing a case between the parties because he had angered BIW’s then-director of labor relations Gerald Stergio with his award in the ‘no smoking’ dispute. He further stated to Mr. Nolon that he did not want to continue on the ‘strike list.’”

According to the union, Cooper served as an arbitrator in labor cases 15 times between 2001 and 2009, but since ruling in favor of the union in September 2009, he had not been chosen to handle any case by the parties. The suit asked the court to vacate Cooper’s February ruling in the grievance related to outsourcing.

BIW argued that the the union had not filed its complaint within Maine’s 90-day time limit to challenge an arbitrator’s award, and that despite evidence of bias before the arbitrator’s decision, the union failed to raise the question at the time.

On Aug. 11, U.S. District Court Judge George Z. Singal ruled in favor of a motion by BIW to dismiss the lawsuit, writing that “each of these reasons provides an independent and sufficient basis for the court to dismiss the complaint.”