There is no single Latin term that perfectly captures the modern concept of "law of assassination" or "killing the head of state." The Latin language and Roman legal system were more specific and contextual.

• For "law of assassination," the most accurate term is the Lex Cornelia de sicariis et veneficis. This translates to "The Cornelian Law concerning Assassins and Poisoners."[1, 2] This was a domestic Roman law from 81 BC that broadly criminalized murder by a "dagger-man" (sicarius) or with poison (venenum).[1, 2]
• For "killing the head of state," Roman and Latin terminology varied depending on the political context and whether the act was seen as a crime or a justified political killing:
  • Tyrannicidium: This Latin term for "tyrannicide" was used to describe the killing of a political leader considered a tyrant.[3, 4] The assassination of Julius Caesar, for example, was framed this way by his conspirators, who saw it as a justified act to restore the Roman Republic.[3, 5]
  • Regicide: The word "regicide" comes from the Latin roots regis ("of monarch") and cida ("killer").[6, 7] However, the Romans of the Republic and Empire typically avoided calling their rulers "kings" (rex), as the title was deeply associated with tyranny after the last Roman king was overthrown.[8] Therefore, while a valid Latin-derived word, it was not commonly used for the killing of an emperor.[5]
  • Nex imperatoris: This phrase, which directly translates to "murder of an emperor," was another way to describe the act.[9]