Definition
Vis expulsiva (Latin: "expulsive force") is a term from medieval English law denoting force used to expel a person from possession of land or other property — that is, force directed not merely at a person's body but at ousting them from what they hold. It stands as a distinct category within the older common law taxonomy of force, contrasted with vis simplex (simple or bare force) in that its defining purpose is dispossession rather than mere assault or resistance.
Bracton, the thirteenth-century treatise authority, divided vis expulsiva into two subcategories: expulsive force with arms (armata) and expulsive force without arms. Both subcategories share the essential character of being directed toward ejecting a person from possession, but the armed variant carried heightened legal gravity, implicating the possessory assizes and the king's peace more sharply.
The term also extended, in classical usage, to incorporeal hereditaments — rights such as easements or commons — not merely to tangible land and tenements.
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Common Confusion
Vis expulsiva is most likely to be confused with two related Latin force terms:
- Vis simplex: bare or simple force, such as ordinary resistance or physical contact not aimed at dispossession. Bracton's contrast between the two is the primary analytical move; a researcher encountering either term in a medieval or early modern source should locate the other.
- Vis armata: armed force, which overlaps with vis expulsiva armata (the armed subcategory of expulsive force) but is not identical. Vis armata can describe any armed force, while vis expulsiva armata is specifically armed force deployed to oust someone from possession.
Conflating these terms flattens a distinction that mattered practically to which writ or assize a dispossessed plaintiff would pursue.
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Recognized Forms
/SUBTYPES
1. Vis expulsiva armata — Expulsive force with arms. The more serious variant, associated with forcible entry and the disruption of peaceful possession by armed means.
2. Vis expulsiva inermis (without arms) — Expulsive force without weapons; still directed at dispossession but lacking the aggravating element of arms.
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Why It Matters in Research
This is a term of exclusively historical significance. No modern jurisdiction maintains vis expulsiva as operative law; it appears in contemporary legal research only when tracing the doctrinal ancestry of forcible entry and detainer, the possessory assizes (novel disseisin in particular), or the broader medieval English law of seisin.
Researchers working in the history of property law or tort law should note several traps:
First, the term appears almost exclusively in sources derived from or commenting on Bracton's De Legibus et Consuetudinibus Angliae. Both Black's and Burrill's definitions trace directly to Bracton fol. 162; a researcher wanting the primary source must go to Bracton himself, not to dictionary entries that merely paraphrase him.
Second, Burrill's entry is more complete than Black's on one critical point: it preserves a fragment of the original Latin extending the concept to incorporeal things ("res incorporales"), including rights in lands and tenements. Black's omits this. A researcher relying only on Black's may underestimate the scope of the concept as Bracton used it.
Third, this term belongs to a cluster of Latin force-taxonomy terms that appear in Year Books and early common law pleading. Encountering it in a primary source usually signals that the surrounding text is analyzing the nature and degree of force as a threshold question for a possessory remedy — not analyzing criminal liability.
Fourth, vis expulsiva has no meaningful connection to modern tort doctrine's use of "force" or to criminal law. Do not attempt to map it onto contemporary frameworks.
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Historical Dictionary Support
Black's and Burrill's are in substantive agreement on the core definition, both tracing to the same Bracton citation. The divergence is one of completeness: Burrill preserves a longer Latin quotation that captures the extension of vis expulsiva to incorporeal property, where Black's stops at the armed/unarmed distinction. Neither dictionary provides any English case law elaboration, which accurately reflects the term's status as a technical artifact of Bracton's systematic jurisprudence rather than a term actively litigated in the Year Books under this Latin label.
Neither dictionary situates vis expulsiva within the assize of novel disseisin, which is the natural procedural home for claims of forcible dispossession in medieval English practice. Researchers should treat these dictionary entries as starting points for Bracton, not as a full account of how expulsive force operated in practice.
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Jurisdictional Note
Vis expulsiva is a term of medieval English common law with no jurisdiction currently applying it as operative doctrine. Its relevance is historical and comparative only.
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