Definition
"De non" is a Latin prefix fragment meaning "of not" or "concerning the not-," used in legal Latin to form phrases denoting negation, absence, or the nonexistence of a fact, right, or act. It does not stand alone as a complete legal term but functions as a component of a family of Latin compound phrases that appear frequently in older common law pleading, writs, and procedural forms.
The most significant compound phrases built on "de non" include:
1. De non apparendo (of not appearing): A principle or plea relating to failure to appear, as in the maxim that one who does not appear is treated as having no right to assert — used in pleading and default contexts.
2. De non decimando (of not tithing): A prescription or claim of exemption from the payment of tithes, historically asserted by certain landowners or ecclesiastical bodies as a right grounded in custom or grant.
3. De non procedendo (of not proceeding): A writ or order directing that proceedings in a lower court be stayed or not continued.
4. De non sane memorie (of not sound memory): A descriptive phrase applied to persons alleged to lack legal capacity by reason of mental incapacity at the time of a relevant act, particularly in will contests and conveyancing disputes.
These and related "de non" phrases operate primarily in the register of ecclesiastical law, equity, and pre-modern common law pleading.
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Common Language
Modern common usage (Wiktionary): Not independently defined. "De" appears as a prefix meaning "of" or "from" (from French and Latin); "non" means "not."
Historical common usage (Webster's 1913): Neither "de non" nor its compound forms are treated as common English vocabulary. Webster's 1913 notes "non" as a prefix of Latin origin meaning "not," used in numerous English formations.
The gap between common and legal meaning is categorical rather than subtle. In ordinary English, "non-" is a living prefix freely attached to any word. In the historical legal context, "de non" phrases are frozen Latin constructions with fixed technical meanings embedded in specific procedural or substantive legal contexts. Recognizing one tells a reader almost nothing about the others; each phrase must be researched on its own terms.
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Why It Matters in Research
Researchers working in Law Mind sources will encounter "de non" phrases almost exclusively in two contexts: (1) older English common law materials, including Year Books, early treatise literature, and register of writs collections; and (2) ecclesiastical law materials, where de non decimando in particular appears in tithes litigation well into the nineteenth century.
The principal research trap is fragmentation. Because these are compound terms, historical indexes may catalogue them under the full phrase, under "de," or under the operative word (e.g., "decimando," "apparendo"). If a search for "de non" in a corpus returns nothing useful, search the operative Latin word directly.
A second trap: the individual "de non" phrases belong to very different areas of law. De non decimando is ecclesiastical property law; de non sane memorie is capacity and probate; de non procedendo is courts and jurisdiction. Do not assume that locating one phrase in a source means the source covers the others.
Rapalje & Lawrence's entry for the adjacent term De Libero Passagio — a writ of free passage — illustrates the typical treatment: a brief Latin identification, a citation to the Registrum Omnium Brevium (Reg. Orig.), and nothing more. Researchers should expect the same compressed treatment for "de non" compounds in historical dictionaries and should plan to cross-reference writ registers and Blackstone's Commentaries for fuller explanation.
The Law Mind corpus connects "de non" concepts most directly to defective legal status doctrines (de facto formation, de facto parentage) through the shared Latin prefix "de," but those are distinct in origin and should not be conflated.
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Historical Dictionary Support
Rapalje & Lawrence does not carry a standalone entry for "de non" but treats adjacent Latin writ phrases — such as De Libero Passagio — in the same compressed register: Latin identification, brief English gloss, and a pointer to the Registrum Omnium Brevium or similar authority. This treatment is representative of how nineteenth-century American legal dictionaries handled Latin writ vocabulary: adequate for identification, insufficient for substantive understanding.
Historical sources generally agree that "de non" compounds are terms of art from English common law and ecclesiastical practice, not creative coinages. Where historical dictionaries diverge is in coverage: English sources such as Tomlin's Law Dictionary and Bouvier's Law Dictionary (various editions) give somewhat fuller treatment to de non decimando given its prominence in English tithes cases, while American dictionaries like Rapalje & Lawrence tend to compress or omit ecclesiastical law vocabulary that had little application in the American legal system after disestablishment.
Researchers should note that no historical dictionary entry for a "de non" phrase substitutes for reading the primary source in which the phrase appears. These are pleading and writ terms whose meaning is largely defined by procedural context.
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Jurisdictional Note
"De non" compounds are principally English common law and ecclesiastical law terminology. In the United States, most of these phrases became obsolete with the abolition of Latin pleading and the disestablishment of ecclesiastical courts. De non sane memorie retains occasional relevance in American will contests and probate proceedings as a historical reference point, but modern courts and statutes use plain-English equivalents.
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Encyclopedia Cross-Reference
The Law Mind Business Organizations & Corporate Law Encyclopedia: Corporate Formation — Defective Incorporation (De Facto, Corporation by Estoppel) [business_41] — relevant for understanding how "de facto" (a related Latin construction) operates in modern doctrine, which may help researchers calibrate the difference between living Latin legal terms and archaic ones like "de non" compounds.
The Law Mind Family Law Encyclopedia: Paternity — De Facto Parent and Psychological Parent Doctrines [family_113] — same cross-reference utility as above.
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