Definition
Factum is a Latin term with several distinct legal meanings, each surviving in active use across different legal contexts. Researchers should identify which meaning applies before treating any source as authoritative.
1. A deed or sealed instrument. In old English law, factum denoted a person's act and deed — specifically a written instrument under seal, used to convey property or create a legal obligation. It was functionally synonymous with charta (charter), though early usage distinguished the two: factum referred to the thing done, charta to the documentary evidence of that act.
2. A fact or evidentiary circumstance. Factum could also mean a fact in evidence — a specific, concrete circumstance offered to establish or defeat a legal claim. In this sense it operates as a synonym for "fact" in formal Latin pleading contexts.
3. Due execution of a will (testamentary factum). In testamentary law, the factum of a will refers to its due and valid execution — not merely the act of signing, but the entirety of what is required to make the instrument legally operative: the testator's capacity, proper formalities, and lawful publication or delivery. This remains the most technically precise and practically significant use of the term in modern legal writing.
4. A culpable or wrongful act. In early English criminal law, factum could denote an unlawful or criminal act, distinguished from fortia (the acts of those who aided or abetted). This sense is archaic and rarely encountered outside historical sources.
5. A written legal argument (appellate brief). In Canadian legal practice and in some other common law jurisdictions, factum is the standard term for the written argument submitted to an appellate court — the document equivalent to what American courts call a brief. It typically contains a statement of facts, issues, argument, and relief sought.
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Common Language
Modern common usage (Wiktionary): Somebody's own act and deed; anything stated and made certain; the due execution of a will; a statement of fact and law delivered before a court; a product (the result of multiplying two numbers).
Historical common usage (Webster's 1913): A man's own act and deed; specifically the product. See Facient.
The gap between common and legal usage is significant in two directions. First, the mathematical sense (product of two numbers) is entirely absent from the legal record and should not inform legal research. Second, the appellate-brief meaning — factum as a filed court document — is a distinctly Canadian procedural usage that neither dictionary captures, yet it is the meaning most likely to appear in contemporary common law research outside the United States. A reader encountering "factum" in a modern Canadian appellate decision is reading a synonym for "brief," not a reference to a deed or a fact.
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Common Confusion
Factum is most frequently confused with two pairs of related concepts:
Fraud in the factum vs. fraud in the inducement. These doctrines are distinct in contracts law. Fraud in the factum (or fraud in the execution) occurs when a party is deceived about the nature or terms of the instrument itself — they did not know what they were signing. Fraud in the inducement occurs when a party understands the instrument but is deceived about surrounding circumstances that led them to sign. The distinction matters for the enforceability of the instrument and the availability of defenses. See the Encyclopedia entry above.
Factum vs. jus. Classical Roman and civil law distinguished between factum (a fact, or the doing of an act) and jus (law or right). The factum-jus distinction shaped how questions of fact and questions of law were allocated across procedural systems and persists in comparative law scholarship.
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Recognized Forms
/SUBTYPES
Factum probandum: The fact to be proved — the ultimate fact in issue that a party must establish.
Factum probans: The evidentiary fact — a subsidiary fact offered as evidence to establish the factum probandum.
Non est factum: Literally "it is not his deed." A common law plea or defense by which a party denies that an instrument is their deed — either because they did not execute it at all, or because they did not understand its nature when they signed it. Non est factum is the direct procedural descendant of the deed-related meaning of factum and remains live doctrine in contract and negotiable instruments law.
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Why It Matters in Research
The primary research trap with factum is meaning-drift by context. The same word, appearing in sources across five centuries, can mean a sealed deed, an evidentiary fact, the due execution of a will, a wrongful act, or a filed appellate brief. Reading any single definition into a source from a different era or jurisdiction will produce error.
For researchers working in testamentary law, the factum of a will is a term of art with specific doctrinal content. Historical sources treat the factum of a will as requiring proof of more than mere signing — courts insisted on evidence of the testator's full legal compliance with execution requirements. Modern will contest litigation still turns on this concept, though the Latin label appears less frequently.
For researchers working in Canadian appellate practice or comparative common law, factum as appellate brief is routine and entirely modern. It will appear in Canadian Federal Court Rules, provincial court rules, and advocacy manuals. Cross-referencing to American sources requires translation: Canadian "factum" = American "brief."
The non est factum defense connects factum to negotiable instruments research. The doctrine developed specifically to protect parties who signed instruments without understanding their character — the blind, the illiterate, those deceived about what they were executing. The scope of the defense has contracted significantly in modern common law; historical dictionary sources reflect a broader formulation than contemporary courts apply.
Researchers using Burrill's will find the most granular treatment of factum's criminal law usage, including the distinction from fortia. This sense does not appear in modern casebooks and should be treated as historical context rather than active doctrine.
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Historical Dictionary Support
The historical dictionaries converge on the deed/act-and-deed meaning as the core Latin sense, but diverge in how they weight the subordinate meanings.
Black's (both editions) leads with the deed meaning and gives prominent treatment to the testamentary factum, quoting Bracton and emphasizing that due execution requires proof beyond mere signing. This framing is consistent with the doctrinal weight the testamentary meaning carried in equity courts.
Bouvier's adds the historically important distinction between factum and charta — factum as the thing done, charta as the written evidence — tracing this to Coke on Littleton and Spelman's Glossary. This is a more technically rigorous analysis than Black's offers and is useful for researchers working with early common law property instruments.
Burrill's alone captures the criminal law usage in any depth, distinguishing factum from fortia in the context of principal and accessory liability and citing Bracton's folio on homicide. Researchers working in the history of criminal complicity doctrine will find Burrill's the most productive starting point.
None of the historical dictionaries addresses the Canadian appellate brief usage, which is entirely a modern procedural development and must be sourced from court rules and contemporary practice materials rather than the shelf dictionaries.
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Jurisdictional Note
In Canadian federal and provincial appellate practice, factum is the standard term for the written argument filed by parties — a usage codified in court rules and entirely distinct from the historical common law meanings. In the United States, the term appears almost exclusively in its historical and doctrinal senses (testamentary factum, non est factum, fraud in the factum). Civil law jurisdictions that inherited Roman terminology use factum in its Latin sense of act or deed, often in contrast to jus.
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Encyclopedia Cross-Reference
Defenses — Fraud in the Inducement vs. Fraud in the Factum (The Law Mind Contracts & Commercial Law Encyclopedia)
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