Definition
Latin: "Together; jointly." INSIMUL is a Latin adverb used in common law pleading to mean that parties acted together or jointly. The term appears most significantly as part of two compound Latin phrases used as technical pleading terms:
1. INSIMUL COMPUTASSENT (or COMPUTASSET): "They [or he] accounted together." The name given to the common count in assumpsit based on an account stated — that is, a count alleging that the parties had settled their accounts between themselves and that the defendant agreed to pay the balance found due. The phrase names the count by its operative Latin words, which described the essential allegation: that the parties had together reckoned and agreed upon the balance owed.
2. INSIMUL TENUIT: "He held together with." A species of the writ of formedon, used in real property actions involving joint tenure or co-tenancy situations.
Common Confusion
INSIMUL COMPUTASSENT (account stated) is sometimes conflated with a general indebitatus assumpsit count for money had and received or for goods sold and delivered. These are distinct common counts. The account stated count is specific: it requires an allegation that the parties actually settled and agreed upon the balance due, not merely that money was owed. A count for money had and received, by contrast, does not require that prior accounting or agreement. The distinction mattered at common law pleading and continues to matter doctrinally in modern account stated claims, which require a mutual agreement on the amount owed, not merely an unpaid debt.
Why It Matters in Research
Researchers encounter INSIMUL almost exclusively in one of two contexts: older common law pleading materials discussing the forms of assumpsit, and historical real property actions involving formedon.
The account stated count — INSIMUL COMPUTASSENT — is the term's most practically significant descendant. Modern account stated doctrine still exists in most American jurisdictions, but the Latin pleading form is long obsolete. A researcher tracing account stated doctrine through historical sources will find the doctrine described under the Latin phrase in authorities predating the mid-nineteenth century shift to code pleading. After the Field Code reforms (1848 onward) and the subsequent adoption of the Federal Rules of Civil Procedure (1938), the Latin count disappeared from practice, replaced by plain-language account stated claims. Historical sources before roughly 1850 will use the Latin name almost exclusively; sources after code pleading reforms will use the English description. Be alert to this discontinuity when tracing doctrine across periods.
INSIMUL TENUIT appears in materials on formedon — an ancient real action — and is unlikely to appear in any modern practice context. Researchers encountering it will be working in deep historical property law materials, likely pre-nineteenth century English or early American sources.
The term INSIMUL itself, stripped of its compound phrases, appears occasionally in Latin pleading recitals simply to assert joint action or joint liability. In those contexts it functions as a Latin adverb, not as a term of art, and should be translated accordingly rather than treated as having independent doctrinal significance.
Historical Dictionary Support
The historical dictionaries agree completely on the core meaning: "together; jointly." Black's (1st and 2nd editions) and Burrill's Law Dictionary all trace the definition to Townshend's Pleadings (Townsh. Pl. 44), suggesting common sourcing from a single pleading authority.
Burrill's is the most expansive of the shelf sources on INSIMUL COMPUTASSENT, explaining that these were "the emphatic words of the count when framed in Latin" — that is, the count took its name from the two most operative words of the Latin pleading formula. This is useful context for understanding why the phrase functions as a count name rather than as a description of the cause of action. Black's 2nd edition adds the gloss that the count averred that parties "had settled their accounts together" and that a balance was agreed to be paid, which captures the practical legal content.
Anderson's Dictionary of Law adds nothing independent, pointing only to its entry under COMPUTARE — a pattern common for Latin terms where the dictionary organizes by the root noun rather than the adverbial modifier.
None of the historical dictionaries trace the subsequent development of account stated doctrine beyond the pleading form itself, leaving a gap that modern contract and commercial law sources must fill.
Jurisdictional Note
Account stated doctrine — the modern descendant of INSIMUL COMPUTASSENT — survives in substantially all American jurisdictions but with varying requirements. Some states require only that the creditor rendered an account and the debtor failed to object within a reasonable time; others require affirmative assent. Researchers should not assume the historical common count maps cleanly onto any particular state's current account stated elements.