임대차계약 종료 후 임차인의 목적물 계속점유와 실질적 이득- 대법원 2018. 11. 29. 선고 2018다240424(본소), 240431(반소) 판결 -

The Supreme Court decision 2018da240424, 240431 decided November 29, 2018 said that, “if the lessee continues to occupy the leased premises after the termination of the lease contract but has not substantially benefited from the premises in accordance with the purpose of the lease contract, the lessee is not obliged to return the unjust enrichment to the lessor, and the lessee is not obliged to return the unjust enrichment either when he left his facilities in the leased object.” I think such legal doctrine of the Supreme Court (“The Doctrine of Substantial Profit”) should be reconstructed as follows. After termination of the lease contract, the lessee is obliged to return the leased object to the lessor. The lessee who occupies or uses the leased premise without just cause after the termination of the lease contract should also return the unjust enrichment to the lessor even if the lessee simply occupies the object without using or benefiting from it. Since the lessor performs and gives the possibility of use and profit of the leased object to the lessee according to the lease contract, the lessee in principle should return such possibility of use and profit as the enrichment obtained by lessor’s performance without legal cause(= Leistungskondiktion) when the lease contract is terminated. However, the above-mentioned principal proposition can be modified in certain circumstances, when there is a simultaneous fulfillment relationship between the lessee’s obligation to return the leased object and the lessor’s obligation to return the deposit for lease. If the lessee under the simultaneous fulfillment relationship should always return the unjust enrichment regardless of his actual profit from the leased object, it is unfair because the lessor need not return the interests from the principal(the deposit money), and the lessee who occupies the leased object in order to get the deposit back can not help suffer losses unilaterally. In this case, the lessor who has sufficient deposit may not actively demand a return of the leased premise to the lessee, because the lessor can easily get the profit from the deposit, and as a result the leased object may be left un-used or under-used being occupied by the lessee for a while. It is inefficient in that the leased object cannot be utilized by other suitable parties quickly. The existence of a simultaneous fulfillment relationship is a necessary condition, but not a sufficient condition to apply the Doctrine of Substantial Profit. Only if we can evaluate objectively that the lessee is occupying the leased object, or benefiting from it just passively and incidentally in order to get the deposit back, then the lessee does not bear the obligation to return the unjust enrichment. Unless these requirements are met, the lessee should return the unjust enrichment to the lessor although the lessee simply occupies the object without using or benefiting from it.