「以不能之給付為標的者契約無效」法則存廢之遞嬗變遷──兼論契約神聖原則對自始不能替代給付損害賠償之影響

Paradigm Schiff for“Initial Impossibility of Performance on the Invalidity of the Legal Transaction”: Influence of Sanctity of Contract on Compensation Instead of Performance

我國民法第246條「以不能之給付為標的者契約無效」法則，繼受德國舊民法第306條之規定，學說咸謂此法則是受羅馬法法諺：「對於不能無義務」（Impossibilium nulla est obligatio）影響。惟此法諺是否得推導出客觀自始給付不能，契約即為無效之範式，為本文首要探索處。觀察德國民法發展曲線，特別是德國新債法在現代化、歐體化與國際化之定調下，已揚棄「以不能之給付為標的者契約無效」法則，轉而訴諸契約為有效之立場。本文將深入分析契約神聖原則對自始客觀給付不能契約效力之滲入，並藉由自始客觀給付不能契約無效或有效法則之消長，描繪出契約不履行典範移轉之路徑。藉由德國債務不履行理論之更迭，反思我國自始給付不能制度所面臨之問題，並為我國自始不能替代給付損害賠償法律效果之建構上，尋求妥適性定位，供我國債務不履行法修正之參考。

Article 246 of Taiwan’s Civil Code stipulates that“If the prestation of a contract is impossible, it is void,”which follows the provisions of Article 306 of the old German Civil Code. This provision is influenced by the Roman legal maxim:“Impossibilium nulla est obligatio”. However, It remains questionable whether this legal maxim can lead to the conclusion that where it is not possible objectively to perform the contract at the time of its conclusion, it is void. This article first deals with the reasons for the formation of this norm and the legal historical background. Then, by observing the development process of German civil law, especially in the course of modernization of German obligation law, it can be deduced that the principle of“If the prestation of a contract is impossible, it is void”is obsolete, and the contract is valid instead. The second part of the article explores the core reasons that influence German legislators to change their legal policies and legal theories. Finally, the article draws a path for the paradigm shift of the legal system of the impossibility of performance in the German Civil Code, as a way to reflect on the problems faced by the initial impossibility in Taiwan. And for the reconstruction of the modernization of Taiwan’s civil law, this article provides an appropriate suggestion to establish a modern system of the impossibility of performance and compensation instead of performance.