Definition
A quasi offense is a civil wrong imputed to a person not because that person directly committed the harmful act, but because another who did commit it is presumed to have acted under that person's authority, direction, or control. Liability attaches vicariously — by operation of law — rather than through personal fault.
The concept originates in Roman and civil law traditions, where the law recognized obligations arising neither from contract nor from a delict personally committed, but from something resembling a delict at one remove. The classic case is an employer held responsible for the tortious acts of an employee acting within the scope of employment. The employer did not strike the blow, defraud the creditor, or cause the harm directly, yet the law treats the wrong as imputable to them.
In modern legal systems, quasi offense functions as the theoretical underpinning for vicarious liability, respondeat superior, and related doctrines. Civil law jurisdictions — particularly those derived from the French and Louisiana traditions — use the term quasi offense (or quasi-délit) as a recognized technical category alongside offense (delict). Common law systems arrived at the same practical results through different doctrinal vocabulary, rendering the term itself largely a historical artifact in Anglo-American usage, though the underlying concept remains central.
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Common Confusion
QUASI OFFENSE vs. OFFENSE (DELICT): An offense or delict is a wrong directly committed by the liable party through their own act or omission. A quasi offense is imputed liability — the person held responsible did not personally commit the harmful act. The distinction matters for understanding how historical civil law sources categorize liability, and why some authorities treat vicarious liability as doctrinally distinct from ordinary tort.
QUASI OFFENSE vs. QUASI-CONTRACT: Both terms invoke the "quasi" prefix to signal a legal fiction — liability imposed by operation of law rather than through actual agreement or actual wrongdoing. But they operate in different domains. A quasi-contract addresses unjust enrichment arising in the absence of a real contract. A quasi offense addresses imputed civil liability for a wrong committed by another. Researchers moving between these terms in historical sources should not conflate the underlying rationale simply because both invoke legal fiction.
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Why It Matters in Research
The term is a trap for researchers working across common law and civil law sources. In civil law systems — and in early American legal writing heavily influenced by Roman and French law — quasi offense is a formal category of the law of obligations, sitting alongside contract, quasi-contract, and delict. In common law sources, the same territory is covered by vicarious liability, respondeat superior, and agency principles, with no equivalent technical term. A researcher encountering quasi offense in a 19th-century Louisiana case, a treatise on Roman law, or a comparative law work is reading a term of art with a specific doctrinal address. The same researcher encountering the concept in a modern American common law jurisdiction will find it dissolved into tort and agency doctrine without the label.
Historical sources vary in how broadly they draw the category. Some narrow quasi offense to the employer-employee situation described in Black's. Others extend it to cover liability for household members, for animals, or for persons under one's care or supervision — reaching results that modern law would classify under negligent entrustment or premises liability. Researchers should not assume the category is coextensive with modern vicarious liability doctrine; it may be broader or narrower depending on the source's jurisdiction and era.
The Louisiana Civil Code is the primary American jurisdiction where quasi offense retains operational force as a legal category, reflecting Louisiana's civil law heritage. Comparative law scholarship and international private law materials will also use the term when analyzing civil law systems.
Cross-referencing quasi offense with quasi-contract is productive because both terms reveal how the law of obligations was systematized in civil law tradition — a system that influenced early American legal education and treatise writing even in common law states.
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Historical Dictionary Support
Black's Law Dictionary defines quasi offense as a wrong "imputed to the person who is responsible for its injurious consequences, not because he himself committed it, but because the perpetrator of it is presumed to have acted under his commands." This definition captures the core imputation rationale precisely, grounding the concept in the authority or command relationship between the defendant and the actual wrongdoer.
The definition is useful but compressed. It anchors quasi offense firmly in the respondeat superior scenario — a superior held responsible for the acts of a subordinate presumed to act on orders. What it does not address is the broader civil law category of liability for persons under one's legal custody or supervision (such as parents for minor children, or guardians for those in their care), which some civil law codes also classified under quasi offense or its equivalent. Researchers relying solely on Black's may underestimate the term's scope in primary civil law sources.
Black's does not contextualize the term within the Roman law framework of the four sources of obligation — contract, quasi-contract, delict, quasi-delict — which is essential background for understanding why the term appears where it does in historical treatises and civil law materials. Supplementing Black's with a Roman law or comparative law reference will fill that gap for researchers working with foundational sources.
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Jurisdictional Note
Louisiana is the principal American jurisdiction where quasi offense retains doctrinal significance as a formal category, owing to the state's Civil Code tradition derived from French law. In all other American jurisdictions, the underlying liability principles are addressed through common law tort and agency doctrine, and the term quasi offense will appear, if at all, only in historical or comparative contexts.
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Encyclopedia Cross-Reference
The Law Mind Contracts & Commercial Law Encyclopedia: Contracts — Classification (Bilateral, Unilateral, Express, Implied, Quasi-Contract) — for the parallel structure of quasi-contract as an imputed obligation, which illuminates how civil law systematized obligations arising by operation of law across both the contractual and delictual domains.
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