The appeal is dismissed.

The costs of appeal shall be borne by the Plaintiff, including those incurred by supplementary participation.

The grounds of appeal are examined.

Article 81 subparag. 1 of the Trade Union and Labor Relations Adjustment Act (hereinafter “Trade Union Act”) provides that “the dismissal of, or disadvantages to, a worker on the ground that the worker has joined or was willing to join a trade union, or intended to organize, a trade union, or conducted any other lawful act for the business of a trade union” shall be a type of unfair labor practices committed by the employer.

In order to establish an unfair labor practice as referred to in the above provision, an employer must make a "justifiable act for the business of a trade union" and make a discriminatory act that gives disadvantages to workers, such as dismissal, on the ground of such act. The assertion of such fact and burden of proof are on the part of claiming that the act is an unfair labor practice.

On the other hand, if an employer at a place of business, whose level of personnel management and bonus payment for workers are subject to the criteria for bonus, has given disadvantage in paying bonus less than that of another trade union members or non-members on the ground that the employer is a member of a specific trade union, such employer’s act may also constitute unfair labor practices.

In such a case, whether an employer’s act constitutes unfair labor practice shall be determined by examining whether there was a statistical significant gap between the two groups in personnel management and the two groups, despite the overall comparison of a group of union members of a specific trade union and a group of union members or non-members of a trade union, whether such gap in personnel management and division was attributable to the employer’s anti-cooperative will to be deemed due to the reason that the difference in personnel management is a member of a specific trade union, and whether the same level of bonus has not been paid even if there was no such discrimination in personnel management and division.