In 176 BC a strange but revealing murder case came before the Roman praetor, M. Popillius Laenas. A woman, unnamed in the sources, was brought before the court on the charge of murdering her mother by bludgeoning her with a club. The woman happily confessed to the monstrous act of matricide. Her fate, then, seemed sealed when she entered Laenas’ court; but she introduced a defence that was as irrefutable as the wickedness of the killing of a parent. She claimed that the deed had been a crime of grief-fuelled vengeance resulting from the deaths of her own children. They, she said, had been deliberately poisoned by her mother simply to spite her and her own actions were therefore justified.
This defence caused the entire system to grind to a halt. The situation was an appalling paradox. In Roman culture, parricide was a crime that provoked a unique horror; there was nothing worse than murdering a parent. The typical punishment was a bizarre form of the death penalty, which involved the perpetrator being sewn into a sack with a monkey, a snake, a dog and a chicken and then thrown into the Tiber to drown. The purpose of the animals is unclear; the purpose of the sack was to deprive the murderer of the air and water, and prevent their bones from touching and defiling the earth. It was impossible to imagine a confessed parricide being left unpunished. Rome, however, had a predominantly self-help justice system, where private families and individuals investigated and punished slights against themselves. It was not the role of the state, particularly during the time of the Republic (510-27 BC), to interfere with such private matters as a vengeance killing within the family. The right independently to enact justice, especially when avenging the death of your own children, was central to the Roman conception of a just world. It was, therefore, equally impossible to imagine such a killing being punished.