Definition
A writ at common law compelling a guardian, bailiff, receiver, or other accountant to render and yield up their accounts to a court. The writ operated as a procedural mechanism to enforce the duty of account — requiring those who held money or property on behalf of another to submit their records for examination and settlement. The writ was grounded in the Statute of Westminster II (1285), chapter 12, which formalized and extended the obligation of accountants to answer for their stewardship.
Computus belongs to the family of writs associated with the action of account, one of the older common law forms of action designed to extract a reckoning from fiduciary-type actors before equity courts fully absorbed that function.
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Common Language
Modern common usage (Wiktionary): The calculation of the date of Easter in the Christian calendar; also, a book of tables used to calculate dates of astronomical events and moveable feasts.
Historical common usage (Webster's 1913): Not separately defined as a discrete English entry; the Latin root computus meant a reckoning or calculation, broadly applied in ecclesiastical and astronomical contexts.
The divergence here is complete. In ordinary and historical ecclesiastical usage, computus refers to the mathematical science of calculating Easter and the liturgical calendar — a subject of considerable medieval scholarship. In law, computus strips away the calendrical meaning entirely and names a coercive procedural writ. A researcher encountering computus in a medieval manuscript must determine from context whether the document is ecclesiastical scholarship or legal pleading; the word does identical duty in two entirely separate disciplines.
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Common Confusion
Computus is sometimes loosely conflated with the action of account (also called account render) itself, but the distinction matters for research. The action of account was the underlying cause of action establishing the right to a reckoning. Computus was the specific writ issued within or following that action to compel actual production of the accounts. A plaintiff might succeed on the action of account but still require the writ of computus to force an obstinate defendant to actually submit records. Similarly, researchers should not confuse computus with audita querela or related post-judgment writs — computus is directed at compelling the accounting stage, not challenging a prior judgment.
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Why It Matters in Research
This is a term that will appear almost exclusively in older English common law sources and early American materials that directly tracked English procedure. Several navigational points:
Temporal boundary: The writ of computus lost practical importance as equity courts — particularly the Court of Chancery — developed efficient machinery for compelling account. By the eighteenth century, equitable bills for account largely displaced the common law writ in practice. Researchers working in nineteenth-century American materials are unlikely to encounter computus as a live procedural tool; when it appears, it is typically in historical or treatise discussion.
Statute of Westminster II: Both Black's editions ground the writ in Westm. 2, c. 12 (13 Edw. I, 1285). Any research into the writ's scope and operation should trace back to this statute and its English case law, not to American statutory authority, which generally did not preserve this writ form.
The Reg. Orig. citation: Both Black's editions cite Reg. Orig. 135, referring to the Registrum Omnium Brevium (Register of Writs), the standard English writ register. This is the primary procedural source for the writ's original form and language. Researchers seeking the writ's original Latin form should consult the Register directly.
Overlap with guardian and fiduciary research: Because computus specifically names guardians, bailiffs, and receivers as its subjects, it appears in historical research on guardianship law, estate administration, and early agency relationships. If tracing the historical duties of guardians to account, computus is a relevant procedural data point showing that common law courts had coercive writ machinery — not just equitable remedies — to enforce those duties.
Ecclesiastical confusion risk in multi-disciplinary archives: Because the same Latin word governed Easter calculation, researchers working in archives that mix ecclesiastical and legal records (common in medieval English collections) must read computus in full documentary context before assuming legal meaning.
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Historical Dictionary Support
Black's Law Dictionary (both the standard edition and the second edition) offer identical, terse definitions: a writ compelling a guardian, bailiff, receiver, or accountant to yield up accounts, founded on Westminster II, c. 12. The entries are substantively identical across editions, suggesting no evolution in how legal lexicographers understood the term between editions — consistent with computus being a historical term of art rather than a living doctrinal concept by the time Black's was compiled.
Neither edition addresses the writ's relationship to the broader action of account, the transition of accounting functions to equity, or the distinction between computus and related writs. Neither edition acknowledges the non-legal meaning of the word, leaving open the disambiguation problem noted above. For a fuller treatment of the action of account and the writ's procedural role, researchers should look beyond Black's to sources such as Fitzherbert's Natura Brevium or Blackstone's Commentaries on the form and function of common law writs.
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Jurisdictional Note
Computus as a live writ form was an English common law instrument. American jurisdictions that adopted English common law forms in the colonial and early republic period technically inherited the writ, but its use in American practice was sparse and largely theoretical. Modern American law has no equivalent writ; the functions it served are now addressed through equitable accounting actions, fiduciary duty litigation, and statutory guardianship accounting requirements that vary by state.
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