The Law of the Twelve Tables orders that he who has stirred up an enemy or who has handed over a citizen to the enemy is to be punished capitally. .
Under the terms of this law, those convicted of perduellio were subject to death either by being hanged from the arbor infelix or by being thrown from the Tarpeian Rock. Their families were not allowed to mourn them and their houses were razed.
History
As the concept of national sovereignty took hold in Rome, perduellio also came to mean an offense which “injured or brought into danger the dignity, supremacy, and power of the commonwealth ”. This included such things as losing an army, violating the rights of the tribunes of the plebs, or usurping a function of the State. In the Ab Urbe Condita, Livyrecorded the first instance of both a trial of perduellio and appeal:
It enraged the fiery youth to hear his sister’s lamentations in the hour of his own victory and the nation’s great rejoicing. And so, drawing his sword and at the same time angrily upbraiding her, he ran her through the body…The king…said: “In accordance with the law I appoint duumvirs to pass judgment upon Horatius for treason . The dread formula or the law ran thus: ‘Let the duumvirs pronounce him guilty of treason; if he shallappeal from the duumvirs, let the appeal be tried; if the duumvirs win, let the lictor veil his head, let suspend him with a rope from a barren tree ; let scourge him either within or without the pomerium.’ Even though the duumvirs found Horatius guilty, Horatius was allowed to appeal and by them was acquitted. However, Horatius’ father had to perform expiatory rites and Horatius himself was forced to pass under the yoke.
But over time with the expansion of the rights of Roman citizens, the use of corporal punishment lessened until the time of Augustus when conviction only carried with it the punishment of aquae et ignis interdictio. The trial was conducted by the duumviri perduellionis, who during the Monarchy were appointed by the king. Later on during the Republic they were proposed by the consuls and formally appointed by the comitia. The judgement of the duumviri was subject to appeal, which generally was tried by the comitia centuriata unlike in Horatius' trial. The prosecution was led by tribunes or aediles. By the late Republic, the archaicperduellio had become largely obsolete, though it could still be used. Its offenses were covered by the law of maiestas which included a broader range of crimes. Perduellio became the designation for a particularly odious type of maiestas.
