Definition
Latin. "In court" or "in the course of trial." In judicio describes the second and formal stage of proceedings in a Roman law action — the phase conducted before a judex (an appointed judge or referee) for actual trial and determination on the merits. It stands in contrast to in jure, the preparatory stage conducted before the praetor, during which the legal issues were framed and the formula (the procedural instruction governing the dispute) was established. Once the praetor sent the matter to a judex, the cause was said to proceed in judicio.
More broadly, the phrase carries the general meaning of "by judicial proceeding" or "judicially" — as opposed to pursuing a remedy by self-help or extrajudicial means. Burrill preserves this extended sense: matters pursued in judicio are those brought through the formal machinery of the courts, contrasted with remedies pursued extra judicially, such as apprehending a thief.
The maxim in judicio non creditur nisi juratis — "in a trial, credence is given only to those who are sworn" — illustrates the phrase's use as a shorthand for the formal trial environment in which evidentiary rules operate.
Common Confusion
IN JUDICIO vs. IN JURE: These two phrases divide Roman civil procedure into its two structural stages and are easily conflated. In jure denoted everything that happened before the praetor in the preliminary phase: parties appeared, claims were stated, defenses raised, and the formula agreed upon. In judicio designated the subsequent phase before the judex, where evidence was heard and judgment rendered. The distinction matters because rules, actors, and procedural consequences differed between the two stages. A researcher encountering either phrase in a civil law context should identify which stage is referenced before drawing conclusions about the procedural posture of the action.
Why It Matters in Research
This is a Roman law and civil law term that migrated into English legal literature primarily through Latin maxims, treatises on civil procedure, and the works of jurists who wrote in the common law tradition with reference to Roman sources. Researchers will encounter in judicio most often in three contexts:
First, in discussions of Roman civil procedure — particularly the formulary system — where the in jure / in judicio division is foundational. Any source discussing the actio, the formula, the praetor, or the judex will implicitly or explicitly invoke this framework.
Second, in Latin maxims. The maxim in judicio non creditur nisi juratis appears in early common law sources, including Croke's reports. Researchers should note that the maxim's Roman procedural context does not translate directly into common law evidentiary doctrine; the phrase is borrowed for its rhetorical force, not as a statement of Roman procedural law applied in an English court.
Third, in comparative law and civil law jurisdiction materials. Scholars drawing on Roman law foundations for continental procedure use in judicio as a technical term of art. Its meaning in those sources is consistent with the classical Roman usage.
The phrase has no independent procedural significance in Anglo-American common law. When it appears in common law sources, it functions as a Latinate gloss on the concept of "in court" or "in the course of judicial proceedings" rather than as a reference to the specific Roman procedural division.
Historical Dictionary Support
Black's (1st and 2nd editions) and Burrill are in close agreement on the core definition. All three treat in judicio as a Roman law term denoting the second stage of the formulary action, conducted before the judex, and all three contrast it explicitly with in jure before the praetor. The entries are substantively identical across the two Black's editions, reflecting the 2nd edition's conservative revision of the 1st.
Burrill adds the most useful dimension: he extends the phrase beyond its technical procedural meaning to the broader sense of "by course of judicial proceeding; judicially; by action," and illustrates the contrast with extrajudicial self-help. This broader sense is important for researchers reading Roman law texts or civil law commentaries where in judicio appears not in the context of the formulary division but simply as a shorthand for "through the courts."
None of the historical dictionary sources address how the phrase functions when lifted out of its Roman procedural context and deployed in English common law texts or maxim collections — a gap researchers should be alert to.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Roman Civil Procedure; Latin Legal Maxims; Formulary System