Definition
A preparatory oath administered in old English legal procedure. The term refers to a preliminary oath taken at the outset of a legal proceeding, typically before a party or witness proceeded to give substantive testimony or undertake a formal legal act. Its function was procedural rather than substantive: to establish the solemnity of what followed and, in the context of oath-based adjudication, to bind the swearer's conscience before the main evidentiary or formal process began.
Why It Matters in Research
This term appears almost exclusively in antiquarian and historical legal sources. Researchers encountering it in old English records, plea rolls, or ecclesiastical court documents should treat it as a marker of pre-modern oath-centered procedure rather than a doctrine with ongoing legal significance. Its presence in a document signals that the record predates or operates within a system where oath-taking had formal procedural stages — a feature of medieval common law, canon law, and early equity practice alike.
Because the term survives only in supplemental material in Black's 2nd Edition and is absent from most standard reference dictionaries, a researcher who finds it in a primary source and searches only later editions of Black's or modern legal databases is likely to come up empty. The supplemental sections of early Black's editions are an underused resource precisely because they preserve terminology that was already archaic at the time of compilation.
Researchers working in ecclesiastical court records or early chancery materials should also be alert to the related practice of the oath ex officio, which had a different procedural character but similarly used preliminary oath-taking as a gateway mechanism. Confusing the two could lead to misreading the procedural posture of a historical record.
Historical Dictionary Support
Black's Law Dictionary (2nd Ed.) Supplemental defines prsjuramentum simply as "[i]n old English law. A preparatory oath." The brevity of the entry is itself informative: by the time Black's was compiled, the term had receded sufficiently from active legal use that no elaboration was thought necessary. No equivalent entry appears in the main body of Black's 2nd Edition, confirming its status as a relic term preserved for reference rather than practice.
Other major historical legal dictionaries — Bouvier's Law Dictionary, Tomlin's Law Dictionary, and Jacob's Law Dictionary — do not appear to carry entries under this exact spelling, though related concepts such as juramentum (oath) and its various forms (juramentum calumniae, juramentum in litem) are treated at length. The absence from those sources reinforces the inference that prsjuramentum was a narrow procedural term of limited circulation even within historical practice, rather than a cornerstone concept of the oath vocabulary.
The root juramentum is classical Latin for oath, and the prefix element signals the preparatory or antecedent character of this particular form. Historical sources on medieval English procedure — including Bracton's De Legibus et Consuetudinibus Angliae — discuss preliminary oaths as structural features of pleading and proof without always using this precise Latin label, suggesting the term may have been used more in learned commentary than in court records themselves.
Jurisdictional Note
The term is exclusively a feature of old English legal history. It has no recognized counterpart in American law and does not appear in civil law systems under this designation. Researchers working in Scottish, Irish, or colonial American records should not assume the term carried identical procedural weight across those jurisdictions even where Latin oath terminology was otherwise shared.