Definition
In Roman and civil law, a Latin adjective meaning silent, unexpressed, or implied — that is, arising from conduct, circumstance, or legal inference rather than from explicit declaration. The term functions as a modifier in several civil law compounds: tacita conditio (a tacit or implied condition), tacitus consensus (implied consent), and related constructions signaling that a legal consequence attaches without having been stated in words.
The concept underlies the broader legal doctrine of tacit agreement or tacit assent: where law or equity treats a party as having consented to, waived, or accepted something by virtue of conduct or silence rather than express statement. In this sense, tacitus is the adjectival root from which the English legal terms "tacit" and "tacitly" derive their technical meaning.
Common Confusion
Tacitus as a legal term should not be confused with the Roman historian Publius Cornelius Tacitus. The word appears in law dictionaries as a Latin adjective in its own right, not as a proper name. Researchers encountering "tacitus" in a civil law context — particularly in glosses on Bracton, in digest citations, or in canon law commentary — should read it as a descriptive modifier, not a personal reference. The Wiktionary entry for TACITUS reflects only the proper noun and a modern medical acronym; neither has any relevance to legal research.
Tacitus also differs from taciturnitas, which is the noun form denoting silence or reticence as a legal act or omission. Where tacitus modifies a condition or agreement ("a tacit condition"), taciturnitas describes the conduct of remaining silent in circumstances where the law may draw an inference from that silence.
Why It Matters in Research
Researchers working in civil law, canon law, or early common law sources — particularly texts derived from Roman law tradition, including Bracton and the English ecclesiastical courts — will encounter tacitus as a recurring modifier. Its significance is navigational: when a Digest passage or a medieval gloss refers to a tacita conditio or tacitus consensus, the researcher must understand that the legal effect being described arises by operation of law or reasonable inference, not by the parties' express words.
This distinction carries real research weight. In contract and property disputes traced through civil law influence, the difference between an express condition and a tacit one affected enforceability, burden of proof, and interpretation. Identifying tacitus in a source flags that the original drafter was invoking the implied-rather-than-expressed framework, which may call for a different line of authority than an express agreement would require.
Burrill's entry for tacitus appears fragmentarily, embedded in a corrupted digest of related terms including tabulae (tablets, especially testamentary tablets). This reflects the dictionary's organizational method of clustering Latin root terms. Researchers should not read the tabulae content as definitionally connected to tacitus — the adjacency is a typesetting or editorial artifact, not a conceptual link.
For Law Mind corpus searches, tacitus as a standalone headword is less productive than searching its English derivatives (tacit, tacitly, tacit condition, tacit consent) or its Latin compound forms. The term is most likely to appear in primary civil law sources and in treatises engaging Roman law doctrine rather than in common law reporters.
Historical Dictionary Support
Burrill's Law Dictionary provides the core entry: "Silent; not speaking; not expressed in words; tacit; implied," citing tacita conditio from Bracton and referencing Digest and Institutes passages. The entry is reliable as far as it goes, but the surviving text is corrupted — material about tabulae (testamentary tablets) appears to have been interpolated or run together with the tacitus entry, likely a transcription or typesetting error. Researchers should treat the tabulae content as a separate item and not read it as part of the definition of tacitus.
No other source dictionaries were submitted for this entry. The standard civil law dictionaries — Calvinus's Lexicon Juridicum, Du Cange's Glossarium — would provide fuller treatment of tacitus and its compound forms, and should be consulted for any serious textual analysis of Roman or canon law sources.
Jurisdictional Note
Tacitus and its derivatives carry weight primarily in civil law jurisdictions (Louisiana, Quebec, Scotland, South Africa) and in historical common law sources with Roman law influence. In purely common law research, the English equivalent "tacit" or the doctrine of implied consent/condition governs, and Latin usage is largely vestigial.