Morphology
Sacertas, -tis n.f. The Latin term was coined by modern scholars. Latin legislative texts mentioned this penalty only through the ritual formula sacer esto or similia.
Etymology
The word is composed of the lemma sacer linked to the Indo-European root *sak-, whose original meaning is not possible to reconstruct. The Hittite language attests the term šaklai, meaning “use, rite, law”.
Testimonies
Inscriptions
The earliest witness of the expression sacer esto is the inscription CIL I²,1. It was inscribed on a stone block (lapis niger), discovered in 1899 by Giacomo Boni and dated to the Augustan Age. The deity of the sacellum is unknown. The boustrophedon inscription prescribed sacertas for anyone attempting to desecrate the place.
Literary sources
Servius and Dionysius of Halicarnassus report that sacertas was imposed on clientes or patroni violating mutual alliance.
In his De verborum significatu, Festus reported two laws imposing sacertas:
Romulus stated sacertas for those guilty of ploratio parentum , that is knocking their own parents;
Numa Pompilius declared sacri those who moved border stones (Dionysius of Halicarnassus in Roman Antiquities, II, 74, 3 confirmed the witness of Festus).
The lexicographer also gave a clear description of the homo sacer under the entry sacer mons.
Livius and Plutarch mentioned a law, enacted by the consul Publicola, who made sacri those accused of plotting to restore the monarchy.
Livius and Dionysius of Halicarnassus talked about sacrosanctitas assigned to tribuni plebis: those who tried to carry out an attack on their life were subject to sacertas.
Only Livius reports sacertas for those who would have liked to create a magistrature free from provocatio ad populum.
Catalogue of occurrences
Inscriptions
CIL I²,1
Discussion / Interpretation
Sacertas was a penalty firstly codified in Ius Quiritium the roman private law used in nomadic age. Those subject to sacertas were consecrated to underworld deities and could be freely killed by anyone without any consequence for their killer. There is a debate whether the murder of homines sacri was mandatory or not and if the homines sacri had to undergo a legal process. Since the homo sacer became an outcast from the roman society and lost every civil right, the negative answer is highly probable for both questions.