正當防衛之成立，以反擊者受到現在不法侵害作為前提。關於口角互毆，所謂現在不法侵害，是否應該僅就形式而言，對於最先受到攻擊的一方，才認定有現在不法侵害之存在，方得成立正當防衛。或者應該採行其他實質標準？在口角互毆的情形中，反擊者事先已預先知道會受到侵害。是否因此負有事先迴避侵害的義務？也就是，預知者得以迴避的方式避免侵害，卻選擇以反擊行為保全權利，是否因此不得成主正當防衛？另外，反擊者具有積極的加害意思，是否因而不得成立正當防衛？正當防衛意思內容為何？當積極的加害意思與避害意思並存時，應如何論處？相互攻擊能否成立正當防衛？本文就上開問題為綜合研究。至於行為是否具備相當性，而成立正當防衛或過當防衛，係屬另一階次的問題，不在本文討論範圍之內。

For proper self-defense to take place, the defender would have to be experiencing illegal violation in the present manner. During verbal arguments and physical conflicts, should the meaning of present illegal violation be defined by the form of action, which is for the party who suffers attacks first to be legal defender for fighting back? Or should it be defined in other ways? The thesis will be discussing the research for the following issues. In the cases of verbal arguments and physical conflicts, the defender would have been given the idea of being hurt sooner or later during the verbal argument. Would the defender then carry the responsibility for avoiding the violation? In other words, would the self-defense become illegal due to the defender having already predicted to avoid the violation but took defenses to protect their own benefit? Moreover, would the self-defense become illegal if the defender showed positive assault intention? What is the meaning for proper self-dense? When positive assault intention and self-defense exist at the same time, how would it be judged?