英美法違約利益歸入救濟之研究

違約救濟向來著重於填補債權人之財產損害，但當債務人因違約獲得利益時，債權人得否不請求損害賠償，反而向債務人請求歸入該利益？我國文獻上未見相關討論，而英美法在「損害賠償不足」時允許債權人主張利益歸入做為補充性救濟手段。具體而言，當契約標的屬於「不可在市場上以相當費用取得替代」之物或行為時，債權人不能透過損害賠償處於「如同契約被履行一般」之狀態，因而必須剝奪獲利根絕債務人違約之動機。此外，被剝奪之利益必須與違約行為有直接因果關係，利用違約機會獲得之利益不包括在內。最後，雖然債權人不必證明債務人刻意違約獲利，但債務人得抗辯自己不具主觀惡性而免除歸入利益之責。違約利益歸入救濟之功能與目的在於預防、懲罰違約以保護債權人之履行利益，避免債務人不當利得，同時確保契約制度之實用性。本文認為，前開功能亦為我國所應追求之目標，故應可參考比較法之經驗設計一套違約利益歸入制度。然而我國法既無一貫的利益歸入理論，在違約救濟體系中亦無適當的請求權基礎。本文認為，在調整構成要件及法律效果之後，不當得利、違約賠償以及類推適用代償請求權均有潛力作為違約利益歸入之請求權基礎，惟其影響可能不僅及於違約案件，具體的影響評估仍有待未來學說發展。

關鍵字

債務不履行；歸入；不當得利；損害賠償；代償請求

並列摘要

Remedy for breach of contracts traditionally focuses on damages, which compensate the creditor in order to redress the loss having been suffered. However, if the debtor profits from the breach, could the creditor claim to disgorge the gains which is not conferred by the creditor, instead of claiming compensatory damages? There are no relevant authorities in Taiwan while many in Anglo-American law. The creditor is awarded disgorgement when compensatory damages is inadequate. Specifically speaking, three elements justifies disgorgement. First, the subject matter of contract should be “not substitutable”, which means it is nearly impossible for the creditor to buy the same kind of subject matter in the market. By depriving the gains, the responsibility to disgorge reduces the debtor’s motivation to breach and thus ensures the creditor’s performance interest. Secondly, the gains should be directly attributable to the breach. This element is meant to exclude the cases where the breach simply gives the debtor the opportunity to profit. Third, although the credit need not prove that the debtor deliberately breach the contract, the debtor may prove the opposite to free from disgorgement. Deterrent rationale and retributive rationale of disgorgement protects the creditor’s performance interest and prevent unjust enrichment. In the meantime, disgorgement gives contracts sufficient institutional protection. These functions are also worth pursuing in Taiwan contract law. Therefore, I advocate that a similar system should be established in Taiwan. In my opinion, potential institutions are unjust enrichment, damages for breach of contract, and the analogy of substitute claim in Taiwan Civil Code. However, this paper mainly focuses on the necessity and legitimacy of disgorgement in Taiwan. The influence of the amendment needs further discussion.