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

Purport of claim and appeal

1...

(2) On May 7, 2005, the Plaintiff asserted that: (a) on May 7, 2005, the Plaintiff borrowed KRW 5 million from C, who is the spouse of the Defendant, and paid KRW 3 million with the intent to partially repay the borrowed amount; (b) in the Daejeon District Court case 2015Gau57387, which claimed a part of the borrowed amount, the Plaintiff did not accept the repayment of the said borrowed amount; and (c) therefore, the Defendant unduly unjust enrichment of KRW 3 million.

As to this, the Defendant asserted that C received KRW 3 million from the Plaintiff upon repayment around October 24, 2008, which the Plaintiff lent to the Plaintiff, not unjust enrichment, and that it could not respond to the Plaintiff’s claim.

3. Determination

A. The unjust enrichment system imposes the duty of return on the benefiting party on the basis of the ideology of fairness and justice in a case where the benefiting party’s property gains lack a legal cause. As such, the system is to resolve such inconsistency by ordering the acquisitor of property value to return the value in a case where there is a change in a certain property value between certain parties and it seems reasonable in a general and formal manner, but the change in property value among them is contrary to the ideology of fairness that is not less than the other laws from a relative and substantive point of view

(See Supreme Court en banc Decision 2014Da5531 Decided June 25, 2015). Therefore, the issue of whether “legal cause” among the elements for establishing unjust enrichment belongs to the normative judgment area based on the principle of fairness, and thus, the determination ought to be reasonably made in consideration of various circumstances, such as the nature of the act of payment or the responsibility and duty of the person who incurred the payment, etc.

Supreme Court Decision 2015Da218068 Decided January 14, 2016