論作為減損義務措施的替代交易──兼評《民法典合同編通則解釋》第61條

替代交易是《民法典合同編通則解釋》首次確立的重要概念。作為減損義務措施的替代交易具有多元正當性，合乎道德、效率、經驗、自治等價值。無論是否導致更好的狀況，由替代交易產生的成本都是可賠償的。在替代交易實際發生時，替代交易的合理期限及其對應的價格或者租金通常可參照原合同計算。在替代交易假設發生時，尋找替代交易的合理期限及其對應的價格或者租金具體可參照特定交易市場解決，並進行個案判斷。然而《民法典合同編通則解釋》第61條第1款似乎只是肯定了尋找替代交易之合理期限對應價格的賠償，未肯定替代交易價格與原合同價格之間的差額賠償，雖有簡單便捷之優點，但並沒有貫徹替代交易的理念，尤其在繼續性合同語境下會產生不適當的後果，且不為既有的諸多司法判決所認同，值得反思。為防止投機行為，法律應當將替代交易不合理的證明責任分配給違約方。

The concept of substitute transaction was established for the first time in the Interpretation of the General Provisions of the Contract Part of the Civil Code. As a mitigation measure, substitute transactions carry multiple justifications, including values such as morality, efficiency, experience, and autonomy. Regardless of whether they lead to a better outcome, the costs arising from substitute transactions are compensable. When a substitute transaction actually occurs, its reasonable period and corresponding price or rent can typically be calculated with reference to the original contract. In hypothetical substitute transactions, the reasonable period and corresponding price or rent can be determined by referencing specific market conditions and assessed on a case-by-case basis. However, Article 61, Paragraph 1 of the Interpretation of the General Provisions of the Contract Part of the Civil Code appears to affirm only the compensation for the price corresponding to the reasonable period for seeking a substitute transaction, without recognizing the compensation for the price difference between the substitute transaction and the original contract. While this simplifies the resolution process, it fails to fully embody the concept of substitute transaction. This is particularly problematic in the context of continuous contracts, leading to inappropriate outcomes that diverge from numerous judicial precedents, warranting further reflection. To prevent speculative behaviors, the law should assign the burden of proving the unreasonableness of a substitute transaction to the breaching party.