Definition
De computo (Latin: "of account") is the name of an ancient common law writ commanding a defendant to render a reasonable account to the plaintiff, or to show cause why such an accounting should not be required. The writ initiated an action in which a party who owed a duty to account — typically a receiver, bailiff, guardian, or agent who had managed another's property or funds — was compelled to come before the court and present a reckoning of receipts and expenditures. If the defendant failed to account or failed to show sufficient cause for refusal, the court could order an accounting and, ultimately, compel payment of any balance found due.
De computo is recognized as the historical foundation of the modern common law action of account, which itself evolved into the equitable remedy of accounting.
Common Confusion
De computo is sometimes loosely conflated with the equitable action for an accounting, but the two are distinct in origin and mechanism. De computo was a common law writ with a specific procedural form; the equitable accounting action developed separately in Chancery and rested on equitable jurisdiction over fiduciaries and confidential relationships. The modern remedy of accounting descends from both lines but is neither. Researchers should not assume that historical cases discussing de computo resolve questions about equitable accounting jurisdiction, or vice versa.
Why It Matters in Research
Researchers encountering de computo in historical sources should treat it as a procedural ancestor, not a living writ. The form died with the formal writ system, but its doctrinal offspring — the action of account and the equitable action for an accounting — survived and remain relevant in modern disputes involving fiduciaries, partners, agents, and receivers.
The key research trap is treating de computo as a substantive legal doctrine rather than a procedural vehicle. The writ itself compelled only the act of accounting; the substantive question of what was owed emerged from the accounting proceeding that followed. Courts sometimes appointed auditors to examine the rendered accounts, a practice that fed directly into the development of equity's accounting jurisdiction.
When tracing historical pleading in pre-nineteenth-century English or early American materials, de computo may appear under variant spellings (de computu, writ of account) or may be referenced obliquely through citations to the Registrum Omnium Brevium or Fitzherbert's Natura Brevium — the two principal sources identified in Black's Law Dictionary for this writ. Researchers using those foundational treatises will find the writ described procedurally in detail.
In American materials, the writ largely disappeared as common law pleading was abolished by the Field Code and later the Federal Rules of Civil Procedure. The action it founded — account — was absorbed either into equity or into simplified civil pleading. Any nineteenth-century American case citing de computo is likely doing so historically or analogically, not as a live pleading.
Cross-reference to computus is important. De computo and computus occupy overlapping conceptual space in historical sources: computus refers to the account itself (the rendered reckoning), while de computo is the writ compelling its production. Researchers who find only one term in a source should check both.
Historical Dictionary Support
The historical sources are unusually consistent on this term. Black's Law Dictionary (both first and second editions), Bouvier's Law Dictionary, and Rapalje & Lawrence all converge on the same core definition: a writ commanding the defendant to render a reasonable account or show cause to the contrary, and the foundation of the modern action of account. There is no meaningful divergence among the sources.
Bouvier adds a cross-reference to computus and credits Black's for the definition, suggesting that by Bouvier's time the term was already treated as historical rather than operative. Rapalje & Lawrence redirect entirely to their entry for computo, indicating the term was sufficiently archaic that even a legal dictionary of the period did not find independent treatment warranted.
What the historical dictionaries do not address is the internal procedure that followed the issuance of the writ — the appointment of auditors, the form of the account to be rendered, or the remedies available if the account proved deficient. Researchers needing that procedural detail must go beyond the dictionary sources to the English Year Books, Fitzherbert's Natura Brevium directly, or secondary treatments of common law pleading history.