According to the Sina Finance app, on Monday, a federal appeals court in the United States ruled that southwest airlines (LUV.US) must face a lawsuit accusing the airline of illegally threatening and punishing over 9,000 pilots who joined a union.

The Fifth Circuit Court of Appeals in the United States made a ruling with 3 in favor and 0 against, stating that the southwest airlines pilot association argued fully that the airline had an "anti-union hostility", allowing the dispute to be submitted to federal court for trial.

A lower court judge ruled that due to the relatively small scale of this dispute, it should be settled through arbitration.

The case originated from southwest airlines deciding to strip an employee named Timothy Roebling of his duties and compensation as an "inspectors of pilots", a group of around 300 pilots who work closely with management and train other pilots.

Southwest airlines ostensibly disciplined Roebling for his use of vulgar language, but the union claims this was because he decided to join the union's inspectors of pilots committee.

Chief Judge Jennifer Walker Elrod, in an opinion written for a panel of the New Orleans Appeals Court, agreed with the lower court judge's view that under the Federal Railway Labor Act, this dispute is relatively small in scale.

However, she noted that southwest airlines made inspectors of pilots worry about retaliation for union association, and that Roebling's supervisor threatened to strip his qualifications, making this case distinct.

She wrote that these allegations 'fully support the union's claim that southwest airlines intentionally 'weaken' or 'destroy' the operational capabilities of the union.'

Southwest Airlines stated in a statement that they do not agree with the court's decision, and strongly deny the union's accusations. 'We are evaluating our options,' the company added.

The union's lawyers did not immediately respond to a request for comment.

The appeals court sent this case back to U.S. District Judge Barbara Lynn of the Dallas federal court, who dismissed the case in September 2023.