However, prior to the enforcement of Article 19 of the Elderly Employment Act, it was possible for an employer to autonomously determine whether to set the retirement age system or the standard for each individual workplace, etc., and thus, it is also possible for the employer to newly establish the retirement age system or shorten the retirement age to be applied to the employees in the employment relationship at the time by amending the rules of employment after obtaining the consent by the collective decision-making method of the employee group. Therefore, even if the above provision is not effective, it cannot be said that the retirement age system is set below 60 years of age through the labor contract, collective agreement

1. Article 19(1) of the Act on Prohibition of Age Discrimination in Employment and Elderly Employment Promotion (hereinafter “the Elderly Employment Act”) amended on May 22, 2013 provides that “an employer shall set the retirement age of workers at least 60 years of age,” and Article 19(2) of the same Act provides that “If an employer sets the retirement age of workers at below 60 years of age, notwithstanding paragraph (1), the retirement age shall be deemed set at 60 years of age.” Since Article 19 of the Elderly Employment Act enters into force, a labor contract, employment rules, or collective agreement that stipulates that the retirement age of workers under 60 years of age shall be deemed null and void to the extent that it violates the foregoing provision. The “retirement age” in this context ought to be calculated on the basis of the actual date of birth (see Supreme Court Decision 2016Da249236, Mar. 9, 2017).

However, prior to the enforcement of Article 19 of the Elderly Employment Act, it was possible for an employer to set up a retirement age system or shorten the retirement age to be applied to employees in labor relations at the time by amending the rules of employment after obtaining the consent by collective decision-making method in a group of workers (see, e.g., Supreme Court Decision 2007Da85997, Feb. 29, 2008). Therefore, even if the above provision is set below 60 years of age through the labor contract, collective agreement, or employment rules, or the initial date of the retirement age is set differently from the actual date of birth, it cannot be deemed null and void.

2. A. The reasoning of the lower judgment and the record reveal the following.

(1) On May 1, 1986, the Plaintiff joined the Intervenor joining the Defendant (hereinafter “ Intervenor”). The Plaintiff’s date of birth stated in the personnel record card at the time of entry was December 14, 1957.

(2) On June 17, 2015, the Plaintiff received a decision to revise the register (age) from the Seoul Northern District Court to correct the date of birth on the Plaintiff’s family relations register as “the date of birth on December 14, 1957” from “the date of birth on February 2, 1958.”

(3) According to the Intervenor’s personnel regulations, the Plaintiff’s retirement age is 58 years old (Article 53(1)); the retirement age is 6.30 if the month in which he/she reaches the retirement age is in January and June; and 12 if the month in which he/she reaches the retirement age is in July and December (Article 53(2)).

(4) In amending the personnel regulations on September 8, 2015, the Intervenor newly established a provision (Article 53(3); hereinafter “instant provision”) that “the counting of the employee’s retirement age is based on the date of birth stated in the personnel record card prepared at the time of entry” (Article 53(3); hereinafter “instant provision”) and obtained the consent of a trade union organized by a majority of the employees of the Intervenor at the time.

(5) On December 31, 2015, the Intervenor issued a personnel order on the retirement age to the Plaintiff.

B. Examining the foregoing factual basis in light of the legal principles as seen earlier, the Plaintiff’s retirement date is deemed December 31, 2015, and thus, the Plaintiff’s retirement date cannot be deemed as an unfair dismissal on the same day by the Intervenor. The reasons are as follows.

(1) Article 19 of the Elderly Employment Act shall apply to the Intervenor’s workplace from January 1, 2016 (Article 19 of the Addenda to the Elderly Employment Act). Since the instant provision was amended and implemented on September 8, 2015, the Intervenor’s workplace shall apply to the Intervenor’s workplace until January 1, 2016.

(2) In establishing the instant provision, the Intervenor obtained the consent of the labor union organized by a majority of workers subject to the instant provision. Therefore, even if the instant provision constitutes an amendment to the rules of employment unfavorable to the employee, the Intervenor satisfies the procedural validity requirements under Article 94(1) of the Labor Standards Act regarding the procedures for the preparation and amendment of the rules of employment.

(3) Before Article 19 of the Elderly Employment Act enters into force, it should be deemed that the date of birth indicated in the personnel record card at the time of entry may be determined as the retirement age calculation date through the revision of the rules of employment, as stipulated in the newly established provision of this case. Therefore, the instant provision cannot be deemed null and void as it infringes the Plaintiff’s right to acquire the basic right

(4) On the sole basis of the circumstances that the Intervenor calculated retirement age based on the date of birth corrected by the court’s decision before the establishment of the instant provision, it is difficult to deem that there was an implied agreement between the Plaintiff and the Intervenor to regard the initial date of retirement age as the actual date of birth.

(5) Ultimately, according to the Plaintiff’s personnel regulations, including the instant provision, the Plaintiff’s date of birth indicated in the personnel record card prepared at the time of entry came to fall under 58 years of age on December 4, 2015. The labor relationship between the Plaintiff and the Intervenor ought to be deemed to have been naturally terminated on December 31, 2015, before the enforcement of Article 19(1) of the Elderly Employment Act.

C. Nevertheless, the lower court determined that the Intervenor’s retirement notice against the Plaintiff constitutes unfair dismissal. In so determining, the lower court erred by misapprehending the legal doctrine on amendment of Article 19 of the Elderly Employment Act and the rules of employment to the disadvantage of the Plaintiff, thereby adversely affecting the conclusion of the judgment. The allegation contained in the grounds of appeal on

3. Therefore, the lower judgment is reversed, and the case is remanded to the lower court for further proceedings consistent with this Opinion. It is so decided as per Disposition by the assent of all participating Justices on the bench.

Justices Lee Dong-won (Presiding Justice)