A Justiça Romana

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. 

For Laenas, the situation was a nightmare. For most of Republican history there was no formal law criminalising homicide: the Roman government was so deliberately decentralised that it did not see itself as a state which was harmed by private homicide. The murder of a private person did not affect the various magistrates’ power, and therefore the state need not interfere.