Definition
A Latin term from old English law meaning a killing. The term derives from the Latin *interficere* (to kill) and appears principally in legal records and pleadings from the medieval and early modern periods of English law, before Latin was displaced from formal legal proceedings. It carried no technical gradation of its own — the term denoted the act of killing as such, with the specific legal character of that killing determined by modifying language. The most significant compound form in the historical record is *felonica interfectio*, meaning a felonious killing, which distinguished culpable homicide from killing in self-defense, accident, or by royal warrant.
Common Confusion
*Interfectio* should not be read as a synonym for murder (*murdrum*) in historical sources. Medieval and early modern English law maintained careful distinctions among homicide, murder, manslaughter, and justifiable killing. *Interfectio* alone signals only that a killing occurred; it does not import malice aforethought or secret slaying, which were the hallmarks of *murdrum*. Researchers encountering *interfectio* in plea rolls or indictments must look to the surrounding language — particularly the presence or absence of *felonica* — before characterizing the legal nature of the act.
Why It Matters in Research
*Interfectio* is a term of Latin pleading, not a substantive legal category, and this distinction is central to reading historical sources accurately. Its appearance is almost entirely confined to Latin legal records — plea rolls, Year Books, and early abridgments — dating from the period when English court proceedings and formal instruments were recorded in Latin. The Pleading in English Act 1362 began the slow shift away from Law French and Latin in proceedings, and Latin was largely abolished from legal records by statute in 1731 (Administration of Justice Act 1731), after which *interfectio* effectively disappeared from live legal usage.
A researcher working in the Law Mind corpus should treat *interfectio* as a marker of record type and period rather than as a doctrine. Its presence tells you: (1) you are likely in a pre-eighteenth-century source; (2) the document is either an original Latin instrument or a learned treatise quoting from one; and (3) the legal significance lies in the full phrase, not the noun alone. The compound *felonica interfectio* maps roughly onto what later law calls felonious homicide, but the fit is imperfect — the categories of felony shifted substantially between the thirteenth and eighteenth centuries, and projecting later homicide doctrine backward onto early uses of this phrase invites anachronism.
Burrill cites *Comb. 39*, a reference to Comberbach's Reports, a collection of late seventeenth-century King's Bench cases. This situates the term at the tail end of Latin legal usage, appearing in reported decisions that were themselves transitional between Latin record-keeping and English reporting conventions.
Historical Dictionary Support
Burrill's Law Dictionary provides the sole entry among the indexed shelf sources. The entry is compact but accurate: it identifies the term as Latin, situates it in old English law, defines it plainly as "a killing," and flags the critical compound *felonica interfectio* with a citation to Comberbach. No other historical dictionary in the Law Mind corpus indexes this term independently, which reflects its narrow role as a term of Latin pleading rather than a freestanding legal concept warranting extended treatment.
Burrill does not distinguish *interfectio* from related Latin killing-terms (*occisio*, *homicidium*, *necare*) that also appear in early legal records, and it does not address the procedural context — appeals of felony versus indictment — in which *felonica interfectio* might be invoked. Researchers should not treat Burrill's entry as exhaustive on the surrounding homicide doctrine.
Jurisdictional Note
*Interfectio* is exclusively an English common law term of Latin pleading. It does not appear as a term of art in Scots law, civil law, or American legal sources. American courts and instruments conducted business in English from the founding period and never adopted this Latin form.