Definition
Assisa de mensuris (Latin: "assize of measures") is a medieval English legal and administrative ordinance establishing a uniform standard for weights and measures throughout the realm. Attributed to Richard I and enacted in the eighth year of his reign (1197), the ordinance required that a common rule govern the measurement of goods across England, eliminating local variation in units of weight and capacity that had created opportunities for fraud in commercial transactions.
The term functions both as the name of the regulatory measure itself and, in some sources, as a reference to the writ or procedural mechanism through which compliance could be enforced. In Burrill's treatment, assisa appears as a genus covering multiple species of real actions (such as assisa novæ disseynsinæ and assisa ultimæ præsentationis), with assisa de mensuris representing the administrative rather than possessory branch of that family.
Common Confusion
The Latin term assisa carries two distinct meanings in medieval English law that researchers must not conflate. In property law, an assisa is a form of real action or writ — the mechanism for recovering seisin of land (see assisa novæ disseynsinæ). In the regulatory context, assisa designates a royal ordinance or statute, often fixing prices, weights, or measures. Assisa de mensuris belongs firmly to the second category. Burrill's entry compounds potential confusion by embedding the definition of assisa de mensuris within a block that also defines property-law assizes, requiring careful reading to separate the two usages.
Why It Matters in Research
Researchers encounter assisa de mensuris primarily in two contexts: medieval constitutional and administrative history, and the background history of commercial regulation and consumer protection law.
The key research trap is terminological collapse. Historical sources use assisa, assize, and assise interchangeably across entirely different legal domains — land recovery, jury procedure, price regulation, and weights and measures — with no consistent signal distinguishing them. A reference to an "assize" in a chronicle or roll must be resolved by context before any inference about legal meaning is possible. Researchers working in plea rolls, pipe rolls, or administrative records from the Angevin period should treat every instance of assisa as ambiguous until the subject matter is confirmed.
The dating also matters. Attribution to Richard I's eighth regnal year (1197) appears consistently across Black's and Burrill's, tracing back to Hale's History of the Common Law. Researchers relying on this attribution should be aware that it derives from Hale's synthesis rather than from a surviving enrolled original, and that the precise textual history of the ordinance is a matter for medievalists, not a settled legal fact.
For corpus researchers, assisa de mensuris connects the Law Mind materials on real property law (through the shared vocabulary of assisa) to materials on commercial regulation, market law, and the early history of standardization in English trade. The term is an entry point into the broader regulatory apparatus of the Angevin crown, including the Assize of Bread and Ale, with which it is conceptually parallel.
Historical Dictionary Support
Black's and Burrill's definitions are nearly identical in substance, both citing Hale's History of the Common Law, chapter 7, as the authority. Neither dictionary provides independent analysis or primary source citation beyond Hale. This convergence signals that both entries derive from a common learned tradition — Hale as the canonical synthesizer of early English legal history — rather than from independent archival research.
Burrill adds marginal value by situating assisa de mensuris within the broader taxonomy of assisa forms, citing Bracton (lib. 4, tract. 1 and tract. 2) and Fleta (lib. 4, c. 1) for the property-law assizes. This juxtaposition, while potentially confusing, is historically instructive: it reflects how medieval and early modern lawyers organized their understanding of the assize as a flexible legal instrument adaptable to both property disputes and administrative regulation.
Neither dictionary engages with what the ordinance actually required in operational terms — which goods it covered, what units it established, or how enforcement was conducted. For that level of detail, researchers must move beyond the dictionary shelf to Hale's text directly, to Stubbs's Select Charters, or to modern historical scholarship on Angevin administration.
Jurisdictional Note
Assisa de mensuris is specific to medieval English law and has no direct analog in American or civil law systems. Its relevance to modern research is historical and comparative rather than operative. Scholars of Scottish or Welsh legal history should note that the ordinance's reach into those jurisdictions during the Angevin period was contested and uneven.