侵害型不當得利的「損及他人」概念，自始就是法律上困難而有爭議的問題，其理論的發展，先由「不法性理論」，再到「內容歸屬理論」，最後仍有不斷的新理論在進行修正及討論。本文即就傳統的「不法理論」及「內容歸屬理論」為介紹並分析利、弊，並就近來的修正理論為分析，希望能得出對於侵害型不當得利最為適切的理論。

The concept of “auf Kosten” (infringement on another person’s rights which causes detrimental impact on such other person’s interests) of “Eingriff” (the type of infringement)within the theory of quantum meruit has been a difficult and controversial issue. The development of the theory started from “Rechtswidrigkeit”, then to “Zuweisungsgehalt”.
Much discussion has occurred on this subject and has spurred the development of new theories. This article would like to introduce and analyze the pros and cons of traditional “Rechtswidrigkeit” theory and “Zuweisungsgehalt” theory. In addition, I would like to
discuss new theory recently developed, and wish to determine the most appropriate “Eingriff”theory for quantum meruit.