The appeal is dismissed.

The request for intervention by the supplementary intervenor shall be dismissed.

The costs of appeal are assessed against supplementary participation.

1. The grounds of appeal are examined.

In a case where an administrative disposition was taken by an administrative agency by applying a provision of a certain legal relationship or fact in applying a certain Act, the legal doctrine clearly stating that the provision of the Act is not applicable to such legal relation or fact, and thus, if an administrative agency takes the disposition by applying the above provision, even though there is no room for dispute over such interpretation, the defect is grave and obvious. However, in a case where there is room for dispute over the interpretation of the provision of the Act as to the legal relation or fact, the legal principles that the provision of the Act is not applicable to such legal relations or fact clearly revealed, and thus, it cannot

(see, e.g., Supreme Court Decisions 2010Du13463, Aug. 23, 2012; 2002Da68485, Oct. 15, 2004). The lower court rejected the Plaintiff’s claim on the ground that the instant disposition cannot be deemed as having a significant and apparent defect, and thus, it cannot be deemed as having a substantial and obvious defect, based on its stated reasoning.

Examining the records in light of the aforementioned legal principles, the above determination by the court below is just, and even if the disposition of this case is unlawful due to the application of the principle of trust protection, such defect cannot be deemed as a significant and apparent defect to the extent that the above disposition itself is null and void. Therefore, the court below did not err by misapprehending the legal principles on the facts against the rules of evidence, failing to exhaust all necessary deliberation, or by misapprehending the legal principles on the invalidity of an administrative act

2. We examine the legitimacy of the participation by the supplementary intervenor in the trial of the court.

When intending to participate in an action to assist one of the parties in a litigation case, there shall be a legal interest in the results of the relevant lawsuit.

The supplementary intervenor to the plaintiff is the plaintiff.