Definition
Latin: "wolf's head." A term from Saxon and early English law designating an outlawed felon who had been placed outside the protection of the law entirely. A person declared caput lupinum was treated as a wolf — a creature of no legal standing — and could be killed by any person who encountered him, without legal consequence to the killer. The status arose from formal outlawry: a judicial process by which a felon who fled prosecution was, after repeated failure to appear, stripped of all legal rights and expelled from the community of the law.
The phrase captures both the condition (legal non-personhood) and the practical consequence (license to kill). Unlike an ordinary criminal who retained some legal personality while awaiting judgment, the caput lupinum had forfeited all claim on the law's protection. He could not sue, own property, or demand trial. He was, in the language of the period, civilly dead and physically forfeit.
Common Confusion
Caput lupinum is sometimes loosely equated with outlawry as a whole, but the term refers specifically to the most extreme consequence of outlawry — the forfeiture of physical protection — rather than to the outlawry process itself. Outlawry is the broader legal mechanism; caput lupinum is the resulting status of the person outlawed. A researcher encountering outlawry proceedings in historical records should look specifically for whether caput lupinum status was formally declared, as the legal effects differed depending on the stage and completeness of the outlawry process.
Why It Matters in Research
This term is almost exclusively encountered in historical legal sources. Researchers working in medieval English law, early common law treatises, or histories of criminal procedure will find it cited in foundational texts — Bracton, Fleta, Coke, and Blackstone all address it. Modern legal systems have no direct equivalent; the concept of outlawry itself was largely abolished in England by the nineteenth century and never took the same form in American law.
When reading historical sources, note that the precise scope of the caput lupinum status was debated even among early writers. Burrill's entry, drawing on Bracton and Fleta, indicates that the license to kill applied specifically when the outlaw resisted capture or attempted to escape — not as an unconditional open license. Black's formulation is somewhat broader ("might be knocked on the head, like a wolf, by any one"). This divergence matters: researchers using these sources to reconstruct the actual historical doctrine should weigh the primary texts (Bracton, Blackstone) rather than relying solely on the dictionary summaries.
The term also appears in comparative legal history as a reference point for discussions of legal personhood, civil death, and the philosophical foundations of rights. If you encounter it in a secondary source arguing about statelessness, denaturalization, or the outer limits of legal exclusion, the author is almost certainly invoking the historical concept metaphorically rather than describing a live legal rule.
One terminological trap: Black's Law Dictionary includes a separate entry for capitulum (a chapter of clergy) immediately adjacent to caput lupinum entries in some editions. These are entirely unrelated terms. Browsing researchers should not conflate them.
Historical Dictionary Support
Burrill's Law Dictionary provides the more detailed treatment, citing Bracton (fol. 128b, 134), Fleta (lib. 1, c. 27, § 13), Mirrour of Justices (c. 4, sect. 4), Coke on Littleton (128b), and Blackstone's Commentaries (4 Bl. Com. 320). This citation cluster is consistent and reliable — all are genuine primary and secondary sources from the classical common law tradition. Burrill also notes the Saxon antecedent (wulfesheofod), which underscores the pre-Conquest origins of the concept.
Black's entry is shorter and omits the qualification about resistance, presenting the kill-on-sight license in somewhat absolute terms. For strict historical accuracy, Burrill's version, with its hedge that the killing was lawful when the outlaw resisted or fled, better reflects the nuance in the underlying primary sources.
Neither dictionary addresses the process by which caput lupinum status was achieved (the stages of outlawry proceeding, the role of the county court, the formal proclamations required) — for that, researchers must go to Bracton directly or to modern scholarship on medieval criminal procedure. The dictionaries capture the endpoint; the path to it is not their concern.
Blackstone's treatment at 4 Commentaries 320 is the most accessible English-language synthesis of the doctrine and remains the standard reference for the concept in historical legal writing.
Jurisdictional Note
Caput lupinum is a concept of English law and has no formal counterpart in American law. While early American jurisdictions inherited elements of English outlawry procedure, the caput lupinum concept — the unconditional (or near-unconditional) license to kill the outlaw — was never adopted as part of American criminal law. Researchers working in American historical sources who encounter references to outlawry should not assume caput lupinum-style consequences applied.