Definition
Latin: "Book of Assizes." A historical collection of English common law cases arising from assizes and other trials held in the country (that is, outside London, in the circuits). The Liber Assisarum is one of the Year Books — the reports of court proceedings compiled during the medieval period — and covers cases from the reign of Edward III (1327–1377). Depending on how the Year Books are counted and organized, it is variously described as the fourth volume of Edward III's reports or the fifth part of the published Year Book series. The distinction reflects differences in how editors and publishers arranged the series across different editions rather than any substantive disagreement about the work itself.
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Why It Matters in Research
Researchers consulting medieval English legal sources will encounter the Liber Assisarum when tracing the early development of assize procedure, common law pleading, and the jury system. It is one of the primary documentary sources for understanding how the assizes — the periodic circuit courts presided over by royal justices — functioned in practice during the fourteenth century.
The chief navigational trap is the inconsistent numbering. Black's Law Dictionary and Burrill describe the Liber Assisarum as the fourth volume of Edward III reports; Rapalje & Lawrence call it the fifth part of the Year Books. Neither description is wrong — they reflect different editorial frameworks across different printed editions of the Year Books. When a secondary source cites the Liber Assisarum by volume number, confirm which edition's numbering convention that source is using before locating the passage.
The cases in this collection deal heavily with assize proceedings: novel disseisin, mort d'ancestor, darrein presentment, and related real property actions. Researchers working on the history of ejectment, seisin, or the development of possessory remedies will find the Liber Assisarum a foundational primary source for the period immediately preceding the major procedural reforms of the later medieval centuries.
Because the Year Books generally, and the Liber Assisarum specifically, are written in Law French with Latin formulae, modern researchers typically work through Maitland's and other scholarly editions or through secondary synthesis in works like Reeves' History of English Law, which all three source dictionaries cite as the secondary authority of record for this collection.
The connection to 3 Reeves' History of English Law is worth noting: that citation appears in both Black's and Burrill's entries, making Reeves the standard secondary reference for contextualizing this source within the broader development of English law. A researcher without direct access to Year Book editions should treat Reeves as the starting point.
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Historical Dictionary Support
The three source dictionaries are in close agreement on substance, with only the volume-numbering discrepancy noted above. Black's Law Dictionary and Burrill's Law Dictionary are nearly identical in text, both citing Reeves' History of English Law at the same location (3 Reeve/3 Reeves' Hist. 148), strongly suggesting a shared source or direct inheritance. Burrill's adds the explicit clarification that the Liber Assisarum "is the fifth part of the published series of the Year Books," which reconciles the apparent conflict with Rapalje & Lawrence's description. Rapalje & Lawrence's entry is brief but notable for pairing the Liber Assisarum entry immediately with the definition of LIBER ET LEGALIS HOMO ("a free and lawful man; one worthy of being a juror") — an editorial choice that reflects the close conceptual link between assize procedure and jury qualification in medieval practice.
None of the three dictionaries provide case-level analysis or examples from the collection itself, which is typical: these entries function as bibliographic identifiers rather than substantive legal definitions. The historical dictionaries collectively tell researchers what this source is and where it sits in the Year Book series, but not what legal principles it contains.
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Jurisdictional Note
The Liber Assisarum is an English medieval source with no direct jurisdictional analogue in American law. Its relevance in U.S. legal research is purely historical — tracing common law doctrines to their English origins — and is most frequently encountered in foundational scholarship on real property and jury procedure rather than in active litigation.
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