Definition
An action from Roman civil law brought against a master (dominus) for obligations arising from transactions conducted by his slave acting under express authorization (jussu). The action allowed a third party who dealt with a slave—on the master's direct command—to hold the master fully liable for that transaction. Because the slave had no independent legal personality under Roman law, the mechanism of the actio quod jussu served to enforce the master's accountability when he had explicitly ordered or authorized the slave's conduct.
The term translates literally as "action on account of the command," with jussu meaning "by the order of." The premise is straightforward: a principal who directs an agent to act cannot later disclaim the resulting obligation simply because the agent lacked formal legal capacity.
Common Confusion
Researchers sometimes treat the actio quod jussu as broadly synonymous with Roman principal-agent liability, but it occupied a specific and narrow position within that framework. The critical limiting factor is the requirement of express command. More general forms of implied authority—arising from a slave's role as a shop manager (institor) or ship captain (exercitor)—triggered different praetorian actions. Equating actio quod jussu with the full doctrine of Roman vicarious liability overstates its reach and obscures the distinctions Roman jurists drew carefully.
Why It Matters in Research
This term appears almost exclusively in the context of Roman civil law sources and scholarship on the historical development of agency and vicarious liability. Researchers working in Anglo-American legal history will encounter it when tracing the doctrinal ancestry of principal-agent liability, respondeat superior, and the law of master and servant.
The actio quod jussu is one of several actiones adiecticiae qualitatis—a family of Roman praetorian actions by which creditors could reach the assets or person of a principal (dominus or pater familias) based on transactions conducted by a subordinate (slave or son in potestate). Understanding where this action sits within that family matters for accurate historical analysis. The related actions—actio institoria, actio exercitoria, and actio de peculio—each had different triggers and different scopes of liability. Conflating them distorts the historical argument.
For researchers using Law Mind corpus materials on agency law, respondeat superior, or the Roman law foundations of common law obligations, this term functions as a gateway concept. It appears in Roman law treatises, civilian legal scholarship, and comparative law discussions more often than in common law case reports.
Historical sources citing Justinian's Institutes (4.7.1), the Digest (15.4), and the Code (4.26) are reliable anchors. Any secondary source referencing this action should be checked against those primary Roman law texts for accuracy of characterization—particularly claims about the scope of liability or whether the master's authorization needed to be explicit.
Historical Dictionary Support
Black's Law Dictionary and Burrill's Law Dictionary offer identical definitions, both tracking directly to the same three Roman law sources: Institutes 4.7.1, Digest 15.4, and Code 4.26. Neither source elaborates on how the action related to the broader family of praetorian agency actions, nor do they situate it within the evolution toward modern agency doctrine.
This convergence reflects the practice of nineteenth-century Anglo-American legal dictionaries treating Roman law terms as relatively settled reference points rather than subjects requiring independent analysis. The entries are accurate as far as they go but compressed to the point of omitting the comparative and doctrinal context that makes the term analytically useful.
What historical dictionaries miss: the significance of the express-command requirement (jussu) as a limiting principle. The actio quod jussu applied only when the master had specifically authorized the transaction. Where authorization was inferred from circumstances—such as placing a slave in charge of a business—the applicable action was typically the actio institoria or actio exercitoria. This distinction is absent from both dictionary entries and must be supplied from Roman law scholarship.
Jurisdictional Note
This is a Roman civil law concept with no direct common law counterpart and no operative role in modern Anglo-American jurisdiction. Its legal relevance today is historical and comparative. Civilian legal systems with Roman law foundations (including those of continental Europe and Louisiana) retain the conceptual lineage, but the specific action as such does not appear in modern codes by this name.