Definition
Latin maxim meaning "for work and labor." The phrase appears in early common law pleading and contract doctrine as a condensed description of the consideration or basis of a claim where one party seeks compensation for services rendered. It signals that the recovery sought is grounded in the performance of labor or work, rather than in a sale of goods, a promise of payment, or some other form of consideration.
In practice, the phrase most frequently appeared in the context of indebitatus assumpsit — an action to recover a debt arising from an implied promise to pay for services already performed. A plaintiff counting pro opere et labore was asserting that the defendant had received the benefit of work or labor and owed payment in return, whether or not any express agreement fixed the amount.
Why It Matters in Research
Researchers encountering this phrase in historical pleadings, case reports, or treatises should understand it as a marker of the common counts in assumpsit, particularly those governing quantum meruit recovery. The phrase itself was not a cause of action but a characterization of the consideration underlying a claim — a shorthand that early English and American courts used to distinguish labor-based claims from other common count categories such as goods sold, money lent, or money had and received.
The single authoritative citation across all three source dictionaries — Comyns' Digest — anchors the phrase firmly in early eighteenth-century English pleading practice. Researchers working in American colonial or early republic sources may encounter it in courts that closely followed English forms, but it largely disappeared from American practice as code pleading displaced common law forms in the mid-to-late nineteenth century. After that transition, the underlying concept survived as quantum meruit or unjust enrichment, but the Latin phrase dropped away.
A trap in historical research: the abbreviated citation "1 Comyns, 18" appears in both Black's editions, with the second edition containing a likely transcription error rendering "Comyns" as "Cornyns." Researchers should treat the second edition's citation as a corruption of the same source, not a separate authority.
Historical Dictionary Support
All three source dictionaries provide essentially identical treatment: a bare translation ("for work and labor") and a single citation to Comyns' Digest. There is no meaningful divergence among them, though the second edition's garbled citation to "Cornyns" is a minor textual corruption worth noting.
The uniform brevity of these entries reflects the phrase's status as a term of art within a well-understood pleading framework. Compilers did not feel the need to elaborate because practitioners encountering the phrase would already know its procedural home in the common counts. What the historical dictionaries do not supply — and what researchers need — is the broader doctrinal context: the phrase sits within the law of implied contract, and its modern heir is the quantum meruit claim in quasi-contract or restitution.
Burrill's treatment is marginally more precise in form, identifying the phrase as "L. Lat." (Law Latin), which correctly distinguishes it from classical Latin and situates it within the technical vocabulary of common law pleading rather than Roman law.
Jurisdictional Note
The phrase originated in English common law pleading and was carried into American jurisdictions that followed English forms. It has no meaningful modern operative significance in any U.S. jurisdiction, having been displaced by code pleading and, subsequently, notice pleading. Researchers in English legal history or early American court records are the primary audience.