1. All appeals by the defendant against the plaintiffs are dismissed.

2. The costs of appeal shall be borne by the Defendant.

purport, purport, and.

1. The underlying facts and the grounds for the court’s explanation on this part of the parties’ assertion are as stated in Articles 1 and 20 of the reasoning of the judgment of the court of first instance, and thus, they are cited by the main text of Article 420 of the Civil Procedure

2. Determination as to the cause of action

A. The relevant legal principle 1) In order for an employer to revise the existing working conditions to a disadvantage to a worker due to an amendment to the rules of employment, consent is required of the employee who was subject to the previous working conditions or the rules of employment, and any amendment to the rules of employment that did not obtain such consent is null and void. 2) In principle, an employer is not allowed to unilaterally impose unfavorable working conditions by depriving the employee of his rights and interests derived from the establishment and amendment of the new rules of employment. However, even if the preparation or amendment of the rules of employment is deemed necessary and the degree of disadvantage that the employee would incur, even if considering the need and the degree of disadvantage that the employee would incur, if it is deemed reasonable under the social social norms to recognize the legal norm of the pertinent provision, its application cannot be denied solely on the ground that there is no consent from the employee subject to the previous

On the other hand, the existence of rationality under social norms ought to be determined by comprehensively taking into account the degree of disadvantage suffered by the employee due to the amendment of the rules of employment, the content and degree of the necessity of the employer, the reasonableness of the contents of the rules of employment after the amendment, measures subject to the amendment, the circumstances leading to negotiations with the trade union, etc. and the response of the trade union or other workers, and the domestic general situation

Provided, That where the rules of employment are modified disadvantageous to workers, consent thereto shall be obtained.