Exodus 22:2

Blood. The reason is, because it could not easily be known whether the thief had not a design upon the life of the people in the house; and therefore, the law gave them authority to defend themselves. But they were not authorized to kill the thief designedly. the laws of Athens and of Rome, permitted nocturnal robbers to be slain, at least when they came armed. (Plato, de leg. ix. &c.) To defend our goods or honour, by killing the aggressor, is contrary to justice and reason. (Calmet)