Definition
Latin: "greater event" or "greater casualty." In civil law, an extraordinary casualty or accident — an event of overwhelming, unforeseeable force that excuses a party from contractual or legal obligation. Classic examples from the Roman sources include fire, shipwreck, and similarly catastrophic occurrences beyond ordinary human control.
Casus major sits at the severe end of a spectrum of accidental events recognized in Roman and civil law. It operates as a defense to liability: a party who suffers or causes loss through a casus major is generally not held responsible, because the event was beyond any reasonable precaution or foresight. The concept is closely related to, and often treated as a subset of, vis major (superior force) and casus fortuitus (fortuitous event), but casus major specifically emphasizes the extraordinary, catastrophic character of the interrupting event.
Common Confusion
Casus major, vis major, and casus fortuitus are frequently used interchangeably in older legal writing, and the boundaries among them are not consistently drawn even within the civil law tradition. The rough working distinction is one of degree and character: casus fortuitus covers accidental events generally; casus major denotes extraordinary casualties specifically; vis major (or force majeure in French-derived usage) emphasizes irresistible external force, particularly acts of public enemies or natural disasters of the most severe kind. In practice, historical sources often collapse these distinctions, and modern force majeure doctrine in common law jurisdictions draws on all three concepts without consistently tracking the original Latin taxonomy.
Why It Matters in Research
Casus major surfaces primarily in historical civil law sources and in treatises on bailment and contract. Researchers encountering the term in 19th-century American or English legal writing should understand they are almost always looking at a translation or adaptation of Roman law principles, mediated through civilian commentators and, in the common law context, through Story's treatise on bailments.
The practical research trap: because casus major, vis major, and force majeure are used interchangeably across sources and eras, a search anchored to the Latin form alone will miss a significant portion of the relevant material. Modern doctrine has largely absorbed this concept under force majeure clauses, impossibility of performance, and frustration of purpose — none of which use the Roman terminology. Researchers tracing the doctrinal lineage of force majeure defenses backward through common law and civilian sources will encounter casus major as a precursor term, but must also track its synonyms.
In bailment law specifically — the context flagged by both historical dictionaries and Burrill's citation to Story — casus major operates as a defense for bailees. A bailee who loses or damages property due to a casus major is excused from liability that would otherwise attach. This is a live research thread in historical commercial law, shipping, and warehouse cases.
The Digest reference (Dig. 44, 7, 1, 4) is to Gaius in the Digest of Justinian and represents the foundational civil law authority. Any research into the Roman law origins should begin there.
Historical Dictionary Support
Black's and Burrill's are in near-perfect agreement on this term, reproducing essentially the same one-sentence definition with the same Digest citation. Burrill adds a reference to Story on Bailments § 240, which is the more practically useful pointer for common law researchers — Story's treatise was the authoritative American treatment of bailment law throughout the 19th century and is where casus major was most thoroughly worked into the common law framework.
Both sources correctly identify the term as civil law in origin. Neither source develops the doctrinal consequences in any depth, and neither addresses the relationship to modern force majeure or impossibility doctrine — a gap that reflects how thoroughly the Latin terminology had already begun to fade from active American legal usage by the time these dictionaries were compiled. Researchers should not expect these entries to resolve questions about how courts actually applied the standard; treatise and case law research is essential for that.
Jurisdictional Note
Casus major as a term of art is most at home in civil law jurisdictions and in historical common law sources drawing on civilian learning. Louisiana, as a mixed jurisdiction, treats these concepts through its Civil Code. In common law states, the functional doctrine survives under modern impossibility, impracticability, and force majeure frameworks, but the Latin terminology is rarely used in contemporary judicial opinions.