Definition
A Latin term from Roman law referring to the formal notice given by a magistrate announcing his intention to impeach a citizen before the popular assembly (the people). The notice specified three elements: the day appointed for the proceeding, the name of the accused, and the nature of the crime charged. Diei dictio was a procedural step in the Roman system of public accusation, functioning as a kind of preliminary announcement that set the impeachment process in motion.
Why It Matters in Research
This term appears almost exclusively in Roman law contexts and enters English legal literature only through historical and comparative legal scholarship. Researchers encountering diei dictio in a source are almost certainly working with a text that draws on classical Roman legal sources or that addresses the history of accusation and public prosecution. It has no operative meaning in common law jurisdictions and was never adopted into English or American practice.
The term is useful as a navigational marker: its presence in a source signals engagement with Roman public law, particularly the mechanisms of popular criminal prosecution (the comitia or tribal assembly as tribunal). Researchers studying the historical development of prosecutorial procedure, grand jury antecedents, or comparative criminal process may find the term in treatises that analogize Roman institutions to English or American ones — but the analogy is loose. The diei dictio bore some resemblance to a formal charge or indictment in its notice function, but it was issued by a magistrate unilaterally rather than by a body of peers.
Because the term is archaic and specifically Roman, it does not appear in modern legal materials. Researchers should not expect to find it in case law or statutes. Its utility is confined to historical legal dictionaries, Roman law treatises, and scholarship on the history of criminal procedure.
Historical Dictionary Support
All four sources are in close agreement on substance. Black's (both editions), Rapalje & Lawrence, and Burrill's Law Dictionary each describe diei dictio as the notice given by a Roman magistrate of his intention to impeach a named citizen before the people, on a specified day, for a specified crime. The consistency across sources reflects a narrow, stable meaning — this term was never contested or evolving in legal lexicography; it was simply borrowed from Roman legal history and catalogued.
Burrill's entry is marginally the most informative, specifying that the accused was mentioned by name and that the crime and the day were both required components, which aligns with the structured nature of Roman legal formalism. Rapalje & Lawrence's entry is the most compressed, offering little beyond a one-line gloss. Neither Black's edition adds interpretive depth; both reproduce essentially the same sentence.
What the historical dictionaries do not provide: any discussion of the procedural consequences of a diei dictio, what happened if the accused failed to appear, how this notice interacted with other stages of Roman prosecution, or which magistrates held the power to issue it. Researchers needing that depth must go beyond legal dictionaries to primary Roman law scholarship.