Definition
Latin. To swear; to take an oath. In its broadest sense, jurare denotes the act of swearing — calling upon God (or a recognized higher authority) as witness to the truth of a statement or the sincerity of a promise. The term appears across Roman civil law, feudal law, and old English common law as the foundational verb describing oath-taking in its formal legal sense.
The maxim preserved in every major dictionary entry — Jurare est Deum in testem vocare, et est actus divini cultus (3 Inst. 165) — frames the act of swearing not merely as a procedural formality but as a religious act: to swear is to call God to witness, and is an act of divine worship. This theological grounding shaped how courts historically treated oath violations as offenses against both law and conscience.
In practice, jurare is the root from which a cluster of procedural concepts in the common law derive: juror, jury, jurat, and abjuration all trace to this Latin infinitive. The term itself rarely appears in modern legal pleadings or statutes, having been displaced by its English equivalents, but it remains essential vocabulary for reading medieval and early modern legal texts.
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Common Language
Modern common usage (Wiktionary): "Jurare" has no meaningful entry in standard modern English dictionaries. It is not a word in ordinary contemporary usage.
Historical common usage (Webster's 1913): Not listed. The term belongs to Latin legal vocabulary and was not absorbed into general English usage.
The absence of a common-language counterpart is notable precisely because the concept — swearing an oath — is entirely familiar. The gap is not between legal and common meaning, but between the Latin term of art and its thoroughly anglicized descendants. Researchers encountering jurare in Latin legal texts should not assume they are reading an exotic concept; they are reading the formal Latin designation for one of the most ordinary procedural acts in Anglo-American legal history.
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Why It Matters in Research
Jurare is primarily a term of the Latin legal record. Researchers working in medieval English law, civil law sources, Year Books, Bracton, or the Institutes of Coke will encounter it as the operative verb in oath-related passages. Because it is a Latin infinitive rather than a term of art defined by statute or case law, its meaning is stable — but its legal context shifts significantly depending on the source.
In the civil law tradition (Digest, Codex), jurare governs a formal procedure for oath-taking in litigation, including the decisory oath by which a party could submit the resolution of a dispute to the adversary's sworn statement. In feudal law, jurare describes the act central to homage and fealty — swearing allegiance. In old English common law, it appears in contexts ranging from witness oaths to compurgation.
The compound form jurare duodecima manu — to swear by twelve hands, meaning an accused swearing with eleven oath-helpers — connects jurare directly to the practice of compurgation, a method of proof abolished in England by 1833. Researchers reading sources that use this phrase must understand they are in a fundamentally different evidentiary world than the modern common law.
The maxim from 3 Institutes 165 (Coke) appears verbatim across Black's (both editions) and Burrill. Its recurrence signals that 19th-century American legal lexicography treated the religious dimension of oath-taking as doctrinally live — relevant to perjury law, competency of witnesses, and the constitutional treatment of affirmations as substitutes for oaths.
Corpus researchers should note that jurare will appear in Law Mind sources primarily as a headword leading to maxims and cross-references, not as a litigated concept with its own doctrine. The real research payoff comes from tracing its derivatives: jurator, jurata, juramentum, and abjurare each carry distinct procedural content.
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Historical Dictionary Support
Black's (1st and 2nd editions) give near-identical entries — a Latin gloss, the Coke maxim in Latin and English translation, and nothing further. Both treat jurare as a vocabulary item requiring only translation, not doctrinal elaboration. This brevity is appropriate: by the time Black's was compiled in the late 19th century, jurare was a historical term, not an operative one.
Burrill is substantially richer. He distinguishes between the civil law usage (citing the Digest and Codex directly) and the old English common law usage (citing Bracton), and includes the compound jurare duodecima manu — absent from both editions of Black's. This makes Burrill the more useful source for researchers working in early English legal materials or comparative civil law contexts. Burrill also cites Best on Evidence, connecting the ancient maxim to mid-19th-century evidentiary treatise literature, a useful bridge for researchers tracing how older Latin doctrine was absorbed (or discarded) in the modern law of evidence.
All three sources quote the same Coke maxim. None engages the question of what happens when the theological premise of the oath — the invocation of God — is contested or unavailable. That question, which became pressing in cases involving atheists, non-Christians, and conscientious objectors, is handled in the doctrine of affirmation, not under this headword.
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Jurisdictional Note
Jurare as a Latin term of art carries no jurisdiction-specific modern meaning — it is a historical and comparative law vocabulary item. However, its derivatives and the doctrines it names (oath, affirmation, compurgation, perjury) vary significantly between common law and civil law jurisdictions. Researchers using jurare as an entry point into oath doctrine should locate jurisdiction-specific sources promptly rather than relying on the general Latin formulation.
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