Definition
Latin: "from a wrong." Ex delicto describes obligations, rights, and causes of action that arise out of a tort, fault, or wrongful act — as distinguished from those arising ex contractu, out of a contract. The phrase functions as a classifier rather than a cause of action in itself.
In both civil law and common law traditions, the law historically sorted the entire universe of private obligations into two great bins: ex contractu (arising from agreement) and ex delicto (arising from wrong). A plaintiff whose claim rested on breach of promise sued ex contractu; a plaintiff whose claim rested on a tort — a trespass, a conversion, a fraud — sued ex delicto.
At common law, the principal forms of action classified as ex delicto were: trespass, case (action on the case), trover, and replevin. These four categories map the historical common law's attempt to channel tort-based grievances into recognized procedural forms.
The phrase appears in two related contexts:
1. To describe the nature of an obligation — an obligation ex delicto is one imposed by law as a consequence of wrongdoing, not one voluntarily assumed by agreement.
2. To describe the character of a cause of action — an action ex delicto is a tort action, as opposed to a contract action.
Common Language
Wiktionary: "Of a legal obligation: arising from a delict or tort, or some other wrongful act."
The term has no meaningful life in ordinary modern English. It appears almost exclusively in legal and academic contexts. Researchers who encounter it in historical sources should treat it as a technical classifier — its function is structural (sorting obligations by their source) rather than descriptive of any particular wrong.
Common Confusion
Ex delicto is frequently encountered alongside in pari delicto, a related but distinct doctrine. Ex delicto simply identifies the source of an obligation or action (arising from a wrong). In pari delicto is an affirmative defense — it bars a plaintiff who participated equally in the wrongdoing from recovering against the other wrongdoer. The two phrases share the root delicto but operate at entirely different levels: one is a classification, the other is a defense.
Researchers should also resist conflating ex delicto with the criminal law concept of delict. In civil law systems, a delict is the civil analog to a tort. In common law sources, ex delicto carries that civil-law heritage but is applied to describe tort-side obligations generally, not criminal liability specifically. The phrase signals civil wrong, not penal consequence — though historical sources occasionally blur this line.
Why It Matters in Research
The ex contractu / ex delicto binary is the load-bearing framework for understanding how pre-code common law organized private law. Researchers working in pleading treatises, equity materials, or any source predating the merger of law and equity will encounter this classification constantly. It is not decorative Latin — it tells you which procedural track applied, which remedies were available, and which defenses could be raised.
Several research traps are worth flagging:
First, the old forms of action map imperfectly onto modern tort categories. Trover, for example, is the historical ancestor of modern conversion; trespass on the case evolved into negligence. When historical sources say an action lies ex delicto in trover, a modern researcher must translate backward from that procedural label to the underlying substantive wrong.
Second, the distinction mattered enormously for limitations periods. Historical statutes of limitations often ran on different clocks for ex contractu versus ex delicto claims. Researching limitations questions in pre-code jurisdictions requires knowing which category the claim fell into.
Third, this classification framework shapes how equity courts analyzed whether concurrent jurisdiction existed. Courts of equity would sometimes decline jurisdiction over claims that were purely ex delicto, deferring to the law courts. Understanding when equity took or refused jurisdiction often depends on correctly reading the ex delicto / ex contractu signal in the source.
Fourth, the doctrine of in pari delicto — now a live defense in contract and commercial litigation — is conceptually downstream of ex delicto thinking. Researchers working backward from modern in pari delicto cases into historical materials will need fluency with the parent classification.
Historical Dictionary Support
The historical dictionaries are in strong agreement on the core definition and classification function of ex delicto. All four sources treat it as a civil law term successfully absorbed into English common law at an early period, used to describe the tort-side half of the fundamental obligations binary.
Burrill's Law Dictionary is the most analytically precise of the sources, explicitly grounding the term in Justinian's Institutes and in Mackeldey's civil law treatise — a useful reminder that this phrase carries civilian pedigree that predates its English adoption. Burrill notes the term was "constantly associated with its opposite ex contractu" and was imported into English law alongside that companion term, a point Bracton confirms for the medieval common law.
Rapalje & Lawrence add a useful practical dimension by enumerating the four common law forms of action that fall within the ex delicto category — case, trespass, trover, and replevin — and by including the maxim Ex delicto non ex supplicio emergit infamia ("Infamy arises from the crime, not from the punishment"), which appears in some historical pleading and character evidence discussions.
Black's Law Dictionary in both editions offers the standard survey definition without adding analytical depth beyond the other sources. Neither edition substantially addresses the remedial and jurisdictional consequences of the classification, which is where the doctrine's research significance actually lies. Researchers should treat the dictionary entries as orientation, not as full accounts of how the distinction operated in practice.
What the historical dictionaries collectively underemphasize is the classification's procedural consequences — the different pleading rules, limitations periods, and equity-court treatment that turned on whether a claim was ex delicto or ex contractu. For that layer, pleading treatises (Chitty on Pleading, Stephen on Pleading) and equity treatises are better sources.
Jurisdictional Note
The ex contractu / ex delicto framework is primarily a feature of pre-code common law pleading systems. With the adoption of the Field Code in New York (1848) and the eventual spread of code pleading and then the Federal Rules of Civil Procedure, the formal procedural significance of the classification faded. It survives primarily in analytical contexts — describing the nature of an obligation, arguing about limitations periods, or litigating in pari delicto defenses — rather than as a live pleading category in modern American practice.
Encyclopedia Cross-Reference
In Pari Delicto and Unclean Hands — The Law Mind Contracts & Commercial Law Encyclopedia (contracts_36). The in pari delicto defense is the most active modern doctrinal descendant of the ex delicto classification framework.