The costs of appeal are assessed against the defendant.

1. On the first ground for appeal

As a matter of principle, an employer may prepare and revise the rules of employment according to his/her intent, but if it is intended to consent by the collective decision-making method of the workers who were subject to the previous rules of employment or the rules of employment when it is disadvantageous to the workers, it is the opinion of a party member that the modification of the rules of employment that did not obtain such consent is invalid unless it is recognized that it is reasonable by social norms (see, e.g., Supreme Court Decisions 78Da1046, Sep. 12, 1978; 88Meu4277, May 9, 198; 89Meu24780, Mar. 13, 1990).

According to the facts duly established by the court below, the employee remuneration rules of the defendant Development Institute amended as of January 1, 1981 changed the employee's retirement allowance payment rate disadvantageous to the employee, and the employee's consent was not obtained by the collective decision-making method of the employee who was subject to the previous rules. As pointed out in the theory of the lawsuit, the defendant Development Institute's amendment of the employee remuneration rules of the government-invested institution was based on one direction of the government in accordance with the Budget and Accounts Act for the purpose of reducing the retirement allowance reduction rate of the government-invested institution which is considerably likely to lose reasonableness compared to the general public at the time, integrating the different retirement allowance reduction rate of the government-invested institution, and promoting the management rationalization of the government-invested institution which is faced with high-quality financial difficulties, and notified the employees after obtaining the resolution of the board of directors and the approval of the competent Minister, and all of the employees did not raise any objection to the amendment, and there was no reason to believe that the above employee's employee remuneration rules were invalid due to the above amendment without the above employees' consent.

2. On the second ground for appeal

As pointed out in the theory of theory, even though Defendant Development Institute notified the amendment of the above rules on employee remuneration, it cannot be deemed that all workers have agreed to the amendment of the above rules on employee remuneration because all employees of Defendant Development Institute continued to work without any objection, and even after the amendment of the above rules on employee remuneration, it cannot be deemed that the above rules on employee remuneration have been ratified by the amendment of the above rules on employee remuneration, just because all employees of Defendant Development Institute continued to work under the revised rules on employee remuneration after the amendment of the above rules on employee remuneration, and the employees including the plaintiffs continued to receive retirement allowances without objection when they retire, it cannot be deemed that the employees ratified the amendment of the above rules on employee remuneration which is null and void. Therefore, there is no reason to discuss this issue.

3. On the third ground for appeal

Even if the collective agreement to accept the above employee remuneration regulations was concluded on December 2, 1991, the court below duly established that all of the plaintiffs retired before that determination, and therefore the above collective agreement cannot be applied to the plaintiffs, it cannot be accepted.

4. On the fourth ground for appeal

After the amendment of the above employee remuneration regulations, the Plaintiffs continued to enter into an annual renewal of the employment contract pursuant to the revised employee remuneration regulations for ten years with knowledge of the amendment without any objection, and even if there are circumstances like the theory of lawsuit, such as receiving retirement allowances calculated according to the revised employee remuneration rate without objection, such circumstance alone does not lead to the Plaintiffs’ assertion disputing the validity of the above employee remuneration regulations in violation of the principle of good faith and the principle of equity, and therefore there is no reason to discuss.

5. Therefore, the appeal shall be dismissed and all costs of appeal shall be assessed against the losing party. It is so decided as per Disposition by the assent of all participating Justices.

Justices Kim Yong-sik (Presiding Justice)