Intentionality and proportionality enter the jurisprudence dealing with rights of defense at the end of the third century of the common era. A rescript of the emperors Diocletian and Maximian to a certain Theodorus in 290 A.D. resolved a legal issue that had arisen from a court case. The question sent to the imperial court must have been: what kind of a defense a person can use if a robber attempts to take his property away. The imperial court’s response coined a new term, “moderamen inculpatae tutelae” that had never been used before, at least not in the sources that are still preserved:
A person lawfully in possession has the right (recte) to use a controlled amount of blameless force (moderamen inculpatae tutelae) to repel any violence exerted for the purpose of depriving him of possession, if he holds it under a title that is not defective.
Kenneth Pennington, Moderamen Inculpatae Tutelae: The Jurisprudence of a Justifiable Defense, 24 RIVISTA INTERNAZIONALE DI DIRITTO COMUNE 27 (2014).