Definition
Non tenent insimul (Latin: "they do not hold together") is a plea in partition actions by which a defendant denies that the parties hold the disputed property jointly. When a plaintiff brings an action for partition — seeking a court-ordered division of co-owned real property — the defendant may respond with this plea to contest the threshold premise of joint ownership itself. In effect, the plea says: before any division can be ordered, the plaintiff must first establish that we actually hold this estate together, because I deny that we do.
The plea is a denial of tenure in common or joint tenure, not a defense on the merits of how property should be divided. It challenges the plaintiff's standing to demand partition at all.
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Common Confusion
Non tenent insimul is sometimes conflated with defenses that admit joint ownership but contest the method or fairness of a proposed division. Those are substantive defenses going to the partition itself. Non tenent insimul is a threshold plea — it denies the co-tenancy relationship entirely and, if sustained, defeats the action before partition is even considered. A researcher encountering this plea in historical pleading records should treat it as jurisdictionally anterior to any merits discussion.
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Why It Matters in Research
This term appears almost exclusively in historical pleading records and treatises on the forms of action. Researchers are unlikely to encounter it in modern litigation, where code pleading has displaced the formal Latin plea system. Its practical significance in the Law Mind corpus is therefore navigational: when it appears in a historical source, it signals a partition action in which the existence of co-tenancy was the contested issue, not the division itself.
Key traps for corpus researchers:
First, the phrase is easily misread in older printed sources. "Insimul" may appear as "insimul" or "in simul" depending on the typesetter, and the plea name is sometimes abbreviated or paraphrased in reports rather than stated in full Latin form.
Second, this plea belongs to a cluster of partition-related pleading terms that a researcher should cross-reference together. The action of partition had its own procedural vocabulary — writ of partition, commissioners in partition, owelty — and non tenent insimul is the specific defense interposed at the first stage of that action.
Third, jurisdictional variation matters here in an indirect way: because partition actions were historically both legal and equitable, courts of equity sometimes handled the same underlying denial of co-tenancy through different procedural mechanisms. A researcher looking at equity records may find the substance of this plea argued without the Latin label.
Fourth, the plea has no meaningful modern successor under notice pleading. A defendant today who denies joint ownership simply denies it in the answer. Understanding that non tenent insimul was a formal, recognized pleading category helps researchers correctly interpret historical case records and treatises that discuss partition procedure.
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Historical Dictionary Support
Both Black's Law Dictionary (1st and 2nd editions) give nearly identical entries, differing only in a minor typographical variation ("plea" versus "plen" in the 2nd edition — the latter an obvious printing error). Both define the plea as a denial, in an action of partition, that the defendant and plaintiff are joint tenants of the estate in question.
Neither edition elaborates on the procedural consequences of the plea being sustained or overruled, nor do they distinguish between joint tenancy and tenancy in common as the operative co-tenancy forms the plea might target. This is a notable gap: at common law, partition actions were available to both joint tenants and tenants in common, and the plea would logically deny either form of concurrent ownership. Historical treatises on real property pleading — such as those by Gould or Stephen on pleading — provide the procedural context that the dictionary entries omit.
The consistency between editions suggests this was a settled term of art rather than one that evolved significantly over time. Its absence from later editions of Black's reflects the decline of formal Latin pleading rather than any change in the underlying concept.
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Jurisdictional Note
Non tenent insimul, as a formal plea, was a feature of common law pleading in England and in American jurisdictions that followed common law forms of action prior to the adoption of code pleading. Its use was confined to jurisdictions and time periods in which partition was pursued as a writ action at law rather than through equity or statutory procedure. Modern partition statutes have displaced it entirely.
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