論德國法給付型不當得利風險分配之規範

依不當得利之規範，不當得利之返還義務人，於原物返還不能時，應償還其價額。此價額之償還義務，於不當得利之返還義務人主張所受利益不存在時，不復存在。在此種情形，原則上民法係規定不當得利請求權人應承擔其相對人所受利益不存在之風險。然而前述風險分配之原則，在考量雙務契約之牽連性質若仍適用於雙務契約無效而生之不當得利回復原狀關係之觀點下，存在著修正之必要性。對於雙務契約無效而生之不當得利受領人是否得主張所受利益不存在抗辯上之爭議，由於其與契約解除後之回復原狀在法制發展與法益評價上具有之相似性，因此宜以參酌修正後德國現行民法第346條第3項之規範內容，做為不當得利當事人間，對於原有不當得利規範上所受利益不存在之風險分配上調整之依據。 According to the norm of unjust enrichment, the recipient of an unjust enrichment is the debtor who has a duty of return. When the object of enrichment is not returned, the price equivalent to the value of the object shall be paid (payment-type unjustified enrichment). The payment obligation of the unjust enrichment shall cease to exist, when the recipient claims that the enrichment received has no longer existed. In such case, in principle, the civil code requires that the claimant of unjust enrichment bear the risk of loss when the recipient has forfeited his interests in enrichment. However, the above rule of risk allocation shall be re-considered in the following circumstance. In the case of invalid bilateral contracts, there are obligations of restoring the status quo ante even where an unjust enrichment is involved. The controversy arises from a recipient of unjust enrichment in case of an invalid contract, whether the recipient may claim that the enrichment received has no longer existed. Because of the similarities of restoring the status quo ante between contract invalidation and contract rescission, it is recommended to apply Article 346, Item 3 of the German Civil Code.