Definition
Old Natura Brevium is the common title of an anonymous English legal treatise written during the reign of Edward III (1327–1377). The work catalogues the writs then most in use in the English common law courts, appending to each writ a short commentary on its nature, proper application, and legal properties and effects. It is not a statute or judicial opinion but a practitioner's reference — an organized account of the writ system as it functioned in the mid-fourteenth century.
The title is Latin for "old nature of writs" or "old book of writs." The "old" in the title is a relative designation: the treatise is called "old" to distinguish it from the later, better-known work of the same name by Sir Anthony Fitzherbert (published 1534), which superseded it in practical use. Fitzherbert's treatise is known as the New Natura Brevium, and the earlier anonymous work is the Old Natura Brevium — though in historical research, the anonymous text chronologically came first.
The work is commonly cited in legal literature as O.N.B. or Vet. N.B. (from the Latin Vetus Natura Brevium, meaning "old" or "ancient" nature of writs).
Common Confusion
The primary confusion in sources is between the Old Natura Brevium and Fitzherbert's New Natura Brevium. The two works share a title, treat the same general subject matter, and appear in citation strings with similar abbreviations. They are distinct texts of different authorship, period, and authority. Fitzherbert's New Natura Brevium (16th century) became the standard practitioner reference and is far more frequently cited in reported cases. When older English cases or treatises cite simply "Natura Brevium" without a qualifying adjective, researchers should determine from context and date whether the reference is to the anonymous 14th-century work or to Fitzherbert's. After the mid-16th century, unqualified references almost always mean Fitzherbert.
Why It Matters in Research
Researchers encountering citations to O.N.B. or Vet. N.B. in early English case law, historical treatises, or American colonial-era materials should treat the Old Natura Brevium as a primary historical source on the writ system — not as binding authority, but as evidence of what writs existed and how they operated during the reign of Edward III. American courts occasionally cited English writ-form treatises in early republic decisions when establishing the procedural heritage of common law remedies; in that context, distinguishing the Old from the New Natura Brevium matters for understanding which historical baseline the court was invoking.
The treatise predates the era of systematic law reporting. Its descriptions of writs are among the few contemporaneous accounts of procedural practice in the Edwardian period, making it important to legal historians tracing the origins of specific forms of action. Reeves's History of English Law (3 Reeves, Eng. Law, 152) discusses the Old Natura Brevium directly and provides context that helps researchers situate the treatise within the broader development of English common law procedure.
The work's significance diminished sharply after Fitzherbert published his treatise in 1534. Fitzherbert explicitly modeled his work on the Old Natura Brevium but expanded, corrected, and updated it. For most practical legal research purposes from the 16th century forward, the Old Natura Brevium was displaced. Its relevance today is almost entirely historical and bibliographic.
Researchers should note that the Old Natura Brevium is not widely held in American law library collections in its original form. References to it in American sources are almost always secondary — appearing through Reeves, Coke, or other commentators who cite it when tracing procedural history.
Historical Dictionary Support
The historical dictionaries are in close agreement on the core description: an anonymous treatise from the reign of Edward III, cataloguing writs in use at that time, with short commentary on each. Burrill provides the most complete description, drawing on Reeves and Crabb's History of English Law, and notes both the commentary function and the relationship to Fitzherbert. Bouvier's description is substantially the same, adding the useful clarification that the "short comment" addressed "the application and properties" of each writ. Rapalje & Lawrence add the significant historical note that "Fitzherbert made it the model of his own treatise" — a point the other dictionaries gesture toward but Rapalje states most directly.
None of the historical dictionaries identify the author or provide a precise date within Edward III's long reign. None address the question of manuscript versus printed transmission, which is relevant for researchers attempting to locate the text. The Black's first edition entry is fragmentary in the source material provided, but the second edition entry closely tracks Burrill.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Forms of Action; Writ System, English Common Law; Fitzherbert, Sir Anthony.