Definition
In old English legal practice, *sai* (from the Latin *sancta*, meaning "holy things") referred to the Gospels or sacred texts upon which oaths were administered. The term also appears in connection with a special writ of privilege — issued under the great seal — granting protection to foreign nationals seeking to pursue legal remedies within the king's dominions when they feared violence or injury to their persons or property from others within those dominions.
Two distinct uses are thus recorded:
1. Sai as sacred objects: The Gospels or other holy items used as the physical medium for oath-taking in formal legal proceedings.
2. Sai as a protective writ: A license or privilege extended to foreign suitors allowing them access to English courts and royal protection while prosecuting their legal claims.
Common Language
Modern common usage (Wiktionary): A sajou; a capuchin monkey.
Historical common usage (Webster's 1913): Refers the reader to "Capuchin" — the monkey of that name, or members of the Capuchin religious order.
The common English word *sai* has no meaningful connection to either legal use of the term. A researcher encountering *sai* in a legal manuscript should not associate it with its zoological or religious-order meanings in general English. The legal term derives from Latin *sancta* and belongs entirely to the vocabulary of oath procedure and royal writ practice.
Why It Matters in Research
Researchers working in pre-modern English legal records — particularly plea rolls, registers of writs, or records of chancery practice — may encounter *sai* in one of two very different procedural contexts. Conflating them, or misreading the term through its common English meaning, would produce a fundamental misunderstanding of the source.
The oath-taking use connects *sai* to the broader study of compurgation, oath-helpers, and the mechanics of proof in early English courts. The writ use connects it to the history of alien access to English courts and the protection afforded to foreign litigants — a topic relevant to research on medieval and early modern international commercial law, letters of safe conduct, and the treatment of foreign merchants under English law.
The Registrum Omnium Brevium (Reg. Orig.) cited by Burrill is a genuine historical source — the Register of Original Writs — which catalogued the forms of writs available in the English common law system. Researchers consulting the Register will find the writ form for this protective privilege at folio 26.
Because *sai* is a narrow, archaic term appearing in a limited range of sources, it will not appear in most standard legal dictionaries beyond specialized historical compilations. Researchers should treat its absence from modern references as expected, not as evidence of error in the primary source.
Historical Dictionary Support
Burrill's Law Dictionary is the sole historical legal dictionary in the Law Mind corpus to provide a substantive entry for *sai*. Burrill identifies both the oath-object meaning and the writ meaning in a compact entry, anchoring the writ usage to the Registrum Omnium Brevium.
No entry for *sai* appears in Black's Law Dictionary (early editions) or Bouvier's Law Dictionary in the corpus, suggesting the term was already receding from active legal vocabulary by the mid-nineteenth century when those works were compiled. This absence reinforces that *sai* is a term of antiquarian legal interest rather than one with continuing doctrinal relevance.
Burrill's entry does not elaborate on the procedural mechanics of the writ — how it was obtained, what conditions it required, or how it differed from letters of safe conduct or other protective instruments. Researchers seeking that depth must turn to the Register itself or to secondary scholarship on alien litigants in medieval English law.
Jurisdictional Note
This term is specific to historical English law and practice. It has no recognized usage or analog in American law, civil law systems, or modern common law jurisdictions.