Definition
Assisa armorum (Latin: "assize of arms") is a medieval English legal term denoting a royal statute or ordinance that required subjects to keep specified weapons and armor in readiness for the common defense. The obligation was not a matter of personal choice but a public duty imposed by the Crown, making military preparedness a legal requirement tied to a subject's station and landholding. The most historically significant example is the Assize of Arms of 1181, issued under Henry II, which categorized subjects by wealth and prescribed the arms each was obligated to maintain. A later iteration appeared under Edward I in the Statute of Winchester (1285), which extended and updated the arms-keeping requirements.
The term belongs to the broader family of assizes — formal royal enactments or ordinances — and should be understood in that institutional context rather than as legislation in the modern sense.
Why It Matters in Research
This term appears almost exclusively in historical legal materials. Researchers encountering assisa armorum in primary or secondary sources should be aware of several navigational points.
First, the Latin form assisa armorum and the anglicized form "assize of arms" appear interchangeably in historical sources, often without explanation. Corpus searches should run both forms.
Second, the connection to constitutional history is significant. Debates in seventeenth- and eighteenth-century England — and later in American constitutional discourse — over the right or duty to bear arms drew on the assise of arms tradition as evidence of the Crown's historical relationship to subject armament. Researchers working on the historical background of the Second Amendment or English Bill of Rights provisions will find the assize of arms cited as foundational context. The connection is indirect but recurring in the literature.
Third, the term intersects with the broader assize framework in medieval English law. Researchers may encounter it alongside assisa de mensuranda terra (assize of measuring land), the Grand Assize, and other royal ordinances of the same period. Understanding assisa armorum as one instance of royal legislative power exercised through the assize mechanism is essential for situating it properly.
Fourth, the Statute of Winchester (1285) is sometimes discussed as superseding or substantially revising the earlier assize of arms. Sources do not always distinguish clearly between these two instruments. The Hale reference cited in both Black's and Burrill's points to Sir Matthew Hale's History of the Common Law, which discusses the assize tradition; researchers should consult that work directly for primary interpretive context.
Historical Dictionary Support
Black's Law Dictionary and Burrill's Law Dictionary give nearly identical entries, both defining the term as "a statute or ordinance requiring the keeping of arms for the common defence" and both citing the same source: Hale's History of the Common Law, chapter 11. The agreement is complete but the entries are thin — neither dictionary offers historical context, dates the specific instruments, or distinguishes the 1181 assize from later revisions.
Both sources reflect the nineteenth-century common law dictionary convention of defining medieval terms by function rather than historical narrative. Researchers should not expect these entries to support constitutional or historical arguments on their own; they establish the bare legal definition and point to Hale, but the substantive research must go further.
What historical dictionaries miss here is the procedural dimension: the assize of arms was not merely a passive ownership requirement but was enforced through local musters and inspections, creating a regulatory mechanism that had implications for local governance and royal authority. That enforcement structure is absent from both dictionary entries.
Jurisdictional Note
Assisa armorum is a term of English medieval law with no direct counterpart in American, Scottish, or other common law jurisdictions. American researchers will encounter it only in historical and constitutional history contexts, not in operative legal materials.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Assize; Arms, Right to Bear; Statute of Winchester