1. Revocation of the judgment of the first instance, and the plaintiff's claim is dismissed.

2. The total cost of the lawsuit is the part resulting from the supplementary participation.

1. The reasoning for the court’s explanation on this part is as follows: (a) except for the addition of “A subdivision” (hereinafter “instant trade union”) following the second part of the judgment of the court of first instance No. 13, the relevant part of the reasoning of the judgment is identical to that of the relevant judgment of the court of first instance; and (b) thus, this part is cited in accordance with Article 8(2) of the Administrative Litigation Act and the main sentence of Article 4

2. The parties' arguments and issues

A. Since the instant rules of employment were amended to be effective by means of collective decision-making with the consent of a majority of the asserted workers, the instant notice of retirement is justifiable in accordance with the retirement age regulations under the above rules of employment.

B. The instant amendment to the rules of employment by the Defendant and the Intervenor did not go through a collective decision-making method, and thus is invalid.

The instant notice of retirement, which was made by applying the retirement age provision of the amended rules of employment, constitutes unfair dismissal.

C. The collective agreement between the Plaintiff and the AA trade union at issue is not applicable to the intervenors, and the rules of employment are not applied to intervenors.

Since the notice of retirement of this case is based on the revised rules of employment, it is problematic whether the amendment of the rules of employment of this case is valid.

Since the revised rules of employment of this case is unfavorable to the employee by reducing the retirement age of the Plaintiff employee, consent by collective decision-making method is required pursuant to Article 94(1) of the Labor Standards Act.

Therefore, we examine whether the above provision of the Labor Standards Act is complied with in the amendment process.

3. Determination

A. If a legal employer intends to revise the existing working conditions to the disadvantage of a worker due to the revision of the rules of employment, the consent is required in accordance with the collective decision-making method of the worker who was subject to the previous working conditions or the rules of employment, and the amendment of the rules