Definition
A Latin term from the civil law meaning "oath." *Jusjurandum* denotes a solemn oath, particularly as the concept appears in Roman law sources, the Books of Feuds, and early natural law writing. It is synonymous with *juramentum*, the more common law-Latin word for oath, and both terms appear in historical legal texts referring to the binding promise or affirmation by which a party invokes divine sanction as a guarantor of truth or fidelity.
The maxim most frequently paired with the term — *jusjurandum inter alios factum nec nocere nec prodesse debet* ("an oath made between others ought neither to hurt nor profit") — captures its most practically important legal application: an oath sworn between third parties cannot be used to bind or benefit those who were not party to it. This principle parallels the broader civil law rule against *res inter alios acta*, and reflects the Roman law concern that oaths derive their obligatory force from the personal, voluntary, and direct act of the swearer.
Why It Matters in Research
Researchers encountering *jusjurandum* in primary sources should note three navigational points.
First, the term is nearly always a marker of civil law or civil-law-influenced text. Its appearance in a document signals that the writer is drawing on Roman law sources — the Institutes, the Digest, or the Corpus Juris — or on feudal law materials. If you encounter it in a common law context, look for a civilian-trained author or a treatise writer consciously importing Roman doctrine.
Second, *jusjurandum* and *juramentum* are used interchangeably by many writers, including Grotius, but they do not always carry identical connotations across all sources. Burrill notes that *jusjurandum* specifically appears in the Books of Feuds (*Libri Feudorum*), which is useful for dating and situating a source. When tracking oath doctrine through medieval and early modern materials, the choice of word can be a soft signal about the intellectual tradition the author is drawing from.
Third, the maxim *jusjurandum inter alios factum nec nocere nec prodesse debet* is cited to Coke's *Fourth Institute* and has a long afterlife in common law evidence and contract discussions. Researchers consulting historical treatises on oath evidence, compurgation, or wager of law will encounter this phrase repeatedly. It connects directly to later common law principles about the non-binding effect of extrajudicial oaths on strangers to a proceeding.
Historical Dictionary Support
Black's and Burrill's entries are brief but complementary. Black's supplies the maxim and its translation without additional gloss. Burrill's is more substantive and more useful for research: it identifies the precise civil law sources (*Institutes* 4.16.1, *Digest* 12.2, *Codex* 4.1), confirms the feudal law usage, and flags Grotius's interchangeable use of both *jusjurandum* and *juramentum* in *De Jure Belli ac Pacis* Book II, Chapter 13.
Both dictionaries agree on the core meaning and cite the same maxim. Neither source explores the substantive doctrine of oaths in depth — for that, researchers must move to the underlying civil law texts or to treatises on oath and evidence in the common law tradition. What the historical dictionaries miss is any treatment of how *jusjurandum* relates to the evolving common law of sworn testimony, judicial oaths, and the oath of allegiance, all of which drew on the civil law conceptual vocabulary even as they developed their own doctrinal rules.