The appeal is dismissed.

The costs of appeal are assessed against the Plaintiff.

The grounds of appeal are examined.

1. Case history and key issue

A. On March 11, 2016, the Plaintiff and the Jeju Labor Union, the only trade union of the Plaintiff’s workplace, concluded a collective agreement, including a union shop clause (hereinafter “instant union shop agreement”) with the purport that “other than those provided for in Article 3 (excluding employees other than crew members), automatically becomes members at the time of employment, and the Plaintiff will work only for its members. The Plaintiff must dismiss an employee who did not join the trade union (Article 2).”

B. On December 9, 2017, the H trade union, a national industrial trade union, established G subdivisions (hereinafter “instant trade union”) at the Plaintiff’s workplace, thereby having multiple trade unions in the Plaintiff’s workplace.

However, the FF trade union in Jeju was a trade union that still joined two-thirds or more of the workers employed in the Plaintiff’s workplace (hereinafter “controlling trade union”).

C. B, C, and D (hereinafter “instant workers”) employed by the Plaintiff on August 26, 2017 entered the instant trade union as soon as the instant trade union was established without the procedure for joining and withdrawing from the dominant trade union.

On December 26, 2017, the Plaintiff dismissed the instant workers pursuant to the instant union shop agreement.

(hereinafter “instant dismissal”) E.

The key issue of the instant case is whether the Plaintiff, an employer, can dismiss the instant workers lawfully and effectively in accordance with the instant union shop agreement where the instant workers who newly joined the Plaintiff did not join the dominant trade union.

2. Article 33(1) of the Constitution of the Republic of Korea provides that "workers shall have the right to independent association, collective bargaining and collective action to improve working conditions."