1. Regarding ground of appeal No. 1

A. The right to impose and collect indemnity under Article 51(1), (4), and (5) of the former State Property Act (wholly amended by Act No. 9401, Jan. 30, 2009; Articles 72(1) and 73 of the current State Property Act) differs from the legal nature of the right to claim a return of unjust enrichment under the civil law. Thus, the State may file a lawsuit against an occupant of unjust enrichment under the civil law as the owner of State property, separate from the exercise of the right to impose and collect indemnity (see Supreme Court en banc Decision 2011Da76402, Jul. 16, 2014).

In addition, the right to impose and collect the indemnity and the right to claim the return of unjust enrichment in the civil law concurrently exist within the same amount, and when the right to claim the return of unjust enrichment in the civil law is extinguished with the satisfaction of the right to claim the return of unjust enrichment, the right

B. Review of the reasoning of the lower judgment and the record reveals the following facts.

(1) From December 3, 2002 to February 6, 2010, the Plaintiff occupied and used the instant real estate owned by the Republic of Korea without permission, and the Defendant imposed and notified the Plaintiff four times on the premise that the Plaintiff occupied the instant real estate without permission.

(2) On January 23, 2009, the Defendant filed a lawsuit against the Plaintiff on January 23, 2009, seeking the return of unjust enrichment equivalent to the royalty of the instant real estate during the period from January 23, 2004 to the end of possession of the Defendant (hereinafter “related lawsuit”), and on October 28, 2009, the judgment became final and conclusive around that time, stating that “the Plaintiff shall pay the amount calculated at the rate of KRW 316,406 per annum from January 23, 2009 to February 4, 2009, KRW 5% per annum from the next day to the day of full payment, and KRW 20% per annum from January 23, 2009 to the day of full payment.”

(3) On December 23, 2009, the Plaintiff paid 24,419,417 won (hereinafter “the instant repayment”) to the Defendant on January 23, 2009, as unjust enrichment due to the possession and use of the instant real estate and delay damages from the date of repayment, which falls under the period from January 23, 2004 to January 23, 2010.

(4) From January 23, 2004 to January 24, 2010, the Defendant classified the amount of the instant reimbursement as the principal of unjust enrichment of KRW 21,291,885 (the “21,471,885 won” of the lower judgment appears to be clerical error) equivalent to the usage fees of the period from January 23, 2004 to January 24, 201 as the damages for delay ordering payment in the above judgment. The Defendant calculated the remainder of KRW 3,127,532 as the principal of the unjust enrichment ordering payment in the above judgment. Of the total occupation period, the amount equivalent to KRW 100 of the usage fees from January 23, 204 to January 24, 2010 to KRW 20% of the total amount of indemnity from KRW 20 to KRW 281,216 to KRW 208,216 to KRW 216,210,216 to the remainder of the compensation period.

C. Examining the foregoing facts in light of the legal principles as seen earlier, since the Defendant’s right to impose and collect indemnity against the Plaintiff and the right to claim for restitution of unjust enrichment concurrently exist within the same amount, it is reasonable to view that the Defendant’s right to claim restitution of unjust enrichment is extinguished upon satisfaction of the reimbursement amount in the instant case and the Defendant’s right to claim restitution of unjust enrichment is also extinguished only within the scope of the amount. Therefore, the Defendant’s compensation and late payment charge based on the previous disposition on the instant reimbursement ought to be deemed to have extinguished as much as the amount repaid is limited to the indemnity and late payment charge for the relevant period of illegal occupation repaid by the reimbursement. Therefore, the instant disposition that issued with respect to the remainder of the indemnity and late payment charge is not unlawful (the Defendant is deemed to have received reimbursement of unjust enrichment by the Plaintiff by January 24, 2010, and thus, it cannot be deemed that such calculation is disadvantageous to the Plaintiff, even if it was deducted from the original amount of indemnity).

Nevertheless, the court below held that the disposition of this case, which urged the payment of indemnities, including the extinguished portion of the compensation, was unlawful, since the indemnity for the period of unauthorized occupation equivalent to the amount of the reimbursement of this case, which was received from the plaintiff upon the lawsuit related to the previous disposition, loses its validity, and the entire obligation to pay the portion was extinguished. In so doing, the court below erred by misapprehending the legal principles on the right to impose and collect indemnity, thereby adversely affecting the conclusion

2. Regarding ground of appeal No. 3

In general, in administrative legal relations, in order to apply the principle of protecting trust to the acts of an administrative agency, the first administrative agency should name the public opinion that is the object of trust to the individual, second, that the public opinion statement of the administrative agency is justifiable and trusted to the individual, there is no cause attributable to the individual, third, that individual should have trusted that opinion statement of the administrative agency, third, that administrative agency should have done any act corresponding thereto, fourth, that is against the above opinion statement of the administrative agency, thereby infringing on the interests of the individual who trusted that opinion statement of the administrative agency. Lastly, when taking an administrative disposition in accordance with the above opinion statement of the administrative agency, it should not be likely to seriously undermine the public interest or legitimate interests of a third party (see Supreme Court Decision 2004Du46, Jun. 9, 2006, etc.).

According to the facts and records established by the court below, the defendant issued a disposition imposing indemnity amounting to the period from January 1, 2008 to December 31, 2008, which was part of the period of claiming the return of unjust enrichment to the plaintiff on June 19, 2009 during which the pertinent lawsuit was in progress. Since the defendant received the instant reimbursement from the plaintiff on December 23, 2009, and the State property in arrears due to the receipt of the said amount was not fully paid to the plaintiff on December 23, 2009, the defendant issued a receipt stating the purport that he would release the seizure of the State property remaining after the date of prompt payment of the indemnity.

Considering such circumstances, the Defendant cannot be deemed to have expressed a public opinion that the Defendant would no longer collect the remainder of the pertinent unauthorized occupation period from the Plaintiff solely on the ground that the Defendant filed a lawsuit against the Plaintiff and received the reimbursement of the instant amount from the Plaintiff.

Nevertheless, the lower court determined that the instant disposition contravenes the principle of trust protection on the ground that the Plaintiff, who filed a lawsuit and paid unjust enrichment, trusted that the obligation to compensate for the pertinent period was extinguished. In so doing, the lower court erred by misapprehending the legal doctrine on the principle of trust protection, thereby adversely affecting the conclusion of the judgment. The grounds of appeal assigning this error are with merit.

3. Conclusion

Therefore, without further proceeding to decide on the remaining grounds of appeal, 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 Kim Yong-deok (Presiding Justice)