Gorleston Psalter, London, British Library add. 49622 fol. 210v

Adhering to the norm of moderamen inculpatae tutelae, means that if you are attacked with arms you may resist with arms. If you would be attacked by persons without arms, you cannot repel your attacker with arms without punishment. But can I not strike back with a lance, knife or sword a person who has struck with a staff, club, or stone? Does the definition of arms include stones and clubs?Is it not permitted to strike back with a larger or longer lance, knife or stone when one is struck with a smaller one? To this last question, I believe it is permitted. To the first question I think that it is permitted to strike with a staff, club or stone no matter what their size, and it is not permitted to strike back with a lance, knife, sword or other metal. This will be judged according to the decision of a judge and good men.

 
Huguccio, Summa decretorum to D.1 c.7 s.v. uiolentiae: Seruato moderamine inculpatae tutele: scilicet ut si armis facta est armis liceat repellere. Nam si sine armis esset facta, non licetet eam impune repellere armis. Set numquid percutientem uirga uel baculo uel fuste uel lapide possum repellere armis, scilicet lancea uel cultello uel gladio? Nonne nomine armorum etiam lapides et fustes continentur? Numquid non licet repercutere maiori et longiori lancea uel cultello uel fuste uel lapide percutientem minori? Hoc ultimo casu credo quod liceat. In primo credo quod pro quantitate et qualitate uirge uel baculi, uel fustis uel lapidis liceat uel non liceat repercutere lancea uel cultello uel gladio uel alio ferro. Et hoc diiudicabitur arbitratu iudicis uel boni uiri.

Summa decretorum, 1: Distinctiones I-XX, ed. Oldřich Přerovský (Monumenta iuris canonici, Series A, 6. Città del Vaticano: Biblioteca Apostolica Vaticana, 2006) 42.