Definition
The first day of the assizes in a particular town or circuit, when the royal commission authorizing the sitting of the court was formally opened and read. On commission day, the judges' authority to hold court in that location was publicly established, and the business of the assizes formally commenced. The term is specific to English practice and belongs to the historical vocabulary of the assize system, which organized the administration of justice across the counties of England and Wales through periodic circuit sittings.
Why It Matters in Research
Commission day is a term of narrow historical application. Researchers will encounter it primarily in English legal materials predating the abolition of the assize system by the Courts Act 1971, which replaced the assizes with the Crown Court. Its significance in a document is almost always procedural and temporal — it marks the starting point from which deadlines, appearances, and other time-sensitive obligations at a particular assize sitting were calculated.
The main research trap is confusion with the surrounding entries in historical dictionaries. Black's and Rapalje & Lawrence both place commission day in close proximity to entries on commission del credere and commission merchant — distinct commercial law concepts with no connection to the assize courts. A researcher scanning a historical source quickly should be careful not to conflate these. The layout of older dictionaries, which often ran entries together on the same page without strong visual breaks, makes this a genuine hazard.
Commission day has no meaningful counterpart in American legal history. The assize system was an English institution. American researchers encountering the term in colonial-era materials or English treatises should read it as a procedural timestamp within the English circuit court framework, not as a concept with domestic U.S. application.
For researchers working in historical English criminal or civil procedure, understanding commission day situates the beginning of a trial calendar. Writs returnable to the assizes, recognizances, and panel summonses were all organized relative to when the commission opened. A date described in relation to "the commission day at [town]" is therefore locating a legal event within the structure of a specific assize sitting.
Historical Dictionary Support
All three source dictionaries agree closely on the definition and its jurisdictional home. Black's defines commission day as "the opening day of the assizes" in English practice. Burrill offers the same definition and credits Wharton's Law Lexicon as his authority. Rapalje & Lawrence tracks identically — "the opening day of the assizes at a particular town" — and cross-references the entry for ASSIZE, which provides useful surrounding context.
The agreement across sources is unremarkable given the term's narrowness: commission day had a fixed, unambiguous meaning in English practice, and there was little occasion for interpretive divergence. None of the three sources provides case law or statutory authority for the definition, reflecting that the term functioned as established procedural vocabulary rather than a contested legal concept.
What the historical dictionaries do not address is the mechanism behind the term — specifically, that the commission in question was the royal commission (issued under the crown's authority) authorizing judges to sit in oyer and terminer, gaol delivery, or nisi prius. Understanding this background is necessary for reading the term correctly in primary sources. The dictionaries treat it as self-evident, which it no longer is for modern researchers.
Wharton's Law Lexicon, cited by Burrill, is a useful supplementary source for additional English procedural vocabulary of this period.
Jurisdictional Note
Commission day is specific to English legal practice. It has no application in American law, which never adopted the assize system. Researchers working in Scottish, Irish, or Welsh historical materials should verify whether local variants of the assize system used the term in the same way, as the commission structure could differ across jurisdictions within the British Isles.