Definition
Ex demissione is a Latin phrase meaning "on the demise of" or "on the lease of." It appears as a formal prefix in the title of ejectment actions, identifying the real party in interest — the lessor whose title is at stake — when the action is nominally brought by a fictitious lessee. The phrase signals that the suit is prosecuted for the benefit of, and upon the right or title derived from, the named party.
In the classic common law form of the action of ejectment, a fictional plaintiff (typically named John Doe) sued a fictional defendant (typically Richard Roe) for possession of land. The real claimant to title — the actual lessor — appeared in the case caption through the formula "John Doe ex demissione [Name of Real Claimant]," meaning John Doe on the demise of, or by the lease from, that named person. The named real party's title was what the action actually tried.
The term is a variant spelling of ex dimissione, which is the more commonly cited form in legal dictionaries and case reporters. The two spellings refer to the same procedural formula and are interchangeable in historical sources.
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Common Confusion
Ex demissione and ex dimissione are variant spellings of the same phrase and carry identical legal meaning. Researchers encountering either form in historical case captions should treat them as equivalent. Neither should be confused with ex parte, which is an unrelated Latin formula denoting action taken on behalf of, or with notice to, only one side of a proceeding.
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Why It Matters in Research
This term is almost exclusively a historical research term. It appears in case captions, court reports, and pleading records from the era of common law ejectment — roughly from the sixteenth century through the mid-nineteenth century in England, and into the late nineteenth century in American jurisdictions that retained the fictional ejectment form before procedural reforms abolished it.
When searching historical reporters, a case styled "Doe ex dem. [Name] v. Roe" or "Doe ex demissione [Name] v. Roe" is an ejectment action brought to establish the title of the named real claimant. The abbreviation "ex dem." is the form most frequently encountered in reported decisions. Researchers unfamiliar with the formula may misread the caption or fail to identify the true parties and the title question actually at issue.
The fictional ejectment form was abolished in England by the Common Law Procedure Act 1852 and replaced with a direct action. American states abolished it at varying times, generally through field code reforms or later procedural consolidation. After abolition, the ex demissione formula disappears from case captions, and actions to try title proceed under statutory forms (quiet title, trespass to try title, and similar actions depending on jurisdiction). A researcher tracing title disputes across the pre- and post-reform periods must recognize that the same substantive question — who holds valid title to land — appears under radically different procedural forms on either side of the reform date.
Because this term anchors a procedural fiction, it has no modern doctrinal life of its own. Its value to the Law Mind researcher is entirely navigational: recognizing it in a historical source and understanding what it signals about the underlying dispute.
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Historical Dictionary Support
Burrill's Law Dictionary defines ex demissione as Latin for "from or on the demise," notes it is usually written ex dimissione, and cross-references that entry for substantive treatment. Burrill's brief treatment reflects the term's status as a variant form rather than an independent concept — the full explanatory weight rests at ex dimissione.
Historical dictionaries generally handle this formula by cross-reference rather than full definition, which is appropriate given that the substance belongs to the law of ejectment and the fictional lease rather than to the phrase itself. What the dictionaries do not adequately flag for modern researchers is the frequency with which "ex dem." appears as a shorthand abbreviation in reporters, or the interpretive work required to reconstruct the real parties and the title question from a caption that foregrounds two fictional names.
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Jurisdictional Note
The ex demissione formula was a feature of common law ejectment jurisdictions. Its use in American courts varied by state depending on whether and how long each jurisdiction retained the common law fictional ejectment form. States that adopted field codes earlier (New York from 1848, for example) abandoned the form sooner; others retained variants well into the late nineteenth century.
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