Definition
A writ of entry in old English real property law, available to a reversioner whose tenant — either a tenant by the curtesy or a tenant for life — had unlawfully alienated the land in fee or in tail, or for another's life, to a third party. The writ was brought by the person holding the reversion against the alienee (the party to whom the tenant had transferred), and it had to be commenced during the lifetime of the offending tenant. Its purpose was to undo an alienation that exceeded the tenant's lawful estate and that prejudiced the reversioner's interest.
The name derives from the Latin, meaning roughly "in a case similar" — reflecting its character as a writ fashioned to address a situation closely analogous to, but not precisely covered by, earlier forms of entry.
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Common Confusion
The term is closely associated with the broader family of writs of entry, and researchers sometimes conflate it with the writ of entry *sur disseisin* or other writs of entry *in the per* and *in the per and cui*. The distinction matters: the *oasu oconsimili* (more standardly rendered *in casu consimili*) was specific to alienations by particular tenants — those holding less than a fee — where the reversioner's prejudice arose not from a disseisin but from an excessive grant made by a lawful possessor. The wrong was the overreach of the tenant's estate, not an unlawful ousting of the plaintiff.
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Why It Matters in Research
This writ is a minor but historically placed mechanism within the system of real actions that dominated English land law before the rise of ejectment. Researchers working with medieval and early modern English property records, plea rolls, or treatise literature should be aware of several navigational points.
First, the spelling in historical sources is highly unstable. The Black's entry renders it "oasu oconsimili," which appears to reflect a transcription error or abbreviation artifact — the standard Latin form is *in casu consimili* ("in a like case"). Researchers searching digitized plea rolls, Year Books, or abridgments should search under *in casu consimili* and its variants rather than the corrupted form appearing in this entry.
Second, the writ belongs to the category of writs of entry rather than the possessory assizes. This is a meaningful distinction for corpus navigation: writs of entry addressed title and seisin in a more indirect manner than the assizes of novel disseisin or mort d'ancestor, and they occupy different sections of the Registers of Writs and the standard abridgments. Fitzherbert's *Natura Brevium* and Booth's *Real Actions* are more likely to yield useful treatment than sources focused on the assizes.
Third, the temporal limitation — the writ had to be brought within the tenant's lifetime — is a critical procedural feature that shaped litigation strategy and is frequently noted in period commentary. After the tenant's death, different remedies applied to the reversioner.
Fourth, like virtually all real actions, the writ of entry *in casu consimili* was effectively abolished by the Real Property Limitation Act 1833 and the Common Law Procedure Act 1860 in England, and by analogous reforms elsewhere. It has no operational significance in modern practice. Its relevance is entirely historical and doctrinal.
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Historical Dictionary Support
Black's Law Dictionary (2nd Ed.) provides the only entry among the shelf sources and gives a workable if compressed definition, citing *Termes de la Ley* — the early English law dictionary attributed to John Rastell and later revised — as its authority. That citation is consistent with the treatment of writs of entry in period sources.
Black's entry is notable for two problems. First, the rendering "oasu oconsimili" is almost certainly a corruption of *in casu consimili*, likely introduced through transcription or typesetting error; the phrase "in CASUS" appearing mid-definition reinforces this reading. Second, the entry is brief to the point of underexplaining the writ's place within the graduated structure of writs of entry — a structure that distinguished writs according to how many degrees removed from the original wrong the current possessor stood. This context is absent from Black's but essential to understanding why distinct writs existed for alienation by a tenant versus disseisin by a stranger.
Researchers seeking fuller treatment should consult Fitzherbert's *Natura Brevium* (which catalogs writs of this family) and Booth's *Real Actions* (1701), both of which provide more systematic accounts than the dictionary literature.
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Jurisdictional Note
The writ was a creature of English common law and had limited transplantation to the American colonies or early American states. American jurisdictions generally relied on ejectment rather than the real actions for land disputes, and the writ of entry *in casu consimili* never established a significant independent foothold in American practice. A handful of New England states retained certain real actions longer than others, but this specific writ is not a feature of American jurisprudence.
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