Kenka-ryoseibai-ho (laws relating to a conflict or fight in which both parties are to blame) are one of the most prominent and important laws in Japanese legal history, and there have been the subject of many preceding researches. However, the purpose and the background of these laws were never clear in those researches, so I think it is necessary to examine them seriously.
The aim of this article is to examine in more detail the process and purpose of the laws dealing with conflict and fighting established by the Mori clan (one of the Sengoku-daimyo).
After purging the Inoue clan (one of their vassals), in 1550 the Mori clan carried out a policy which gave them broad powers to prohibit any other their vassals from giving assistance to any other vassals who were at figiting. In 1572, they enacted a law that took account of the background and the actual details of the fight. Moreover, he prohibited fighting itself and established Kenka-ryoseibai-ho, which was based on their belief that "Hatto" (order) must come before the claims of vassals.
In conclusion, however, I cannot necessarily assert that these Kenka-ryoseibai-ho became general laws as a solution to the problem of vassals' fighting, because the Mori clan had enacted these laws only at times when they were necessary, for example during the periods of war. Furthermore, it may be necessary to reexamine the common belief that Kenka-ryoseibai-ho came into common use for the mediation of fighting in the early modern period.
