Definition
A common carrier is a person or entity whose regular business or calling it is to transport persons, property, or messages for any member of the public who employs and pays for the service. The defining characteristic is the public offer: a common carrier holds itself out generally to serve all comers, rather than contracting selectively with particular parties.
This distinguishes the common carrier from a private or contract carrier, who transports goods only for specific, pre-arranged customers under individually negotiated agreements and owes no duty to the general public.
The category spans modes of transport. Historically it encompassed stagecoach proprietors, ferrymen, and shipping lines. In modern law it includes railroads, commercial airlines, bus lines, freight trucking companies, and pipelines. Telecommunications carriers — and now, in some regulatory frameworks, internet service providers — have been analyzed under common carrier principles, reflecting the doctrine's continuing evolution beyond physical transport.
Two duties flow from common carrier status that do not apply to ordinary bailees or private carriers:
1. Duty to serve: A common carrier may not arbitrarily refuse to transport a person or goods within its capacity and route. Refusal without lawful justification exposes the carrier to liability.
2. Heightened duty of care: Common carriers owe passengers the highest degree of care consistent with the practical operation of their business — a standard more demanding than ordinary negligence. With respect to goods, carriers are historically treated as near-insurers of safe delivery, subject to limited recognized exceptions (acts of God, acts of a public enemy, inherent vice of the goods, fault of the shipper, and order of public authority).
Common Confusion
Common carriers are sometimes conflated with private or contract carriers, and the distinction matters enormously for liability analysis and regulatory treatment. A trucking company that hauls exclusively for one client under a long-term contract is a contract carrier; the same company advertising general freight hauling to the public becomes a common carrier. The carrier's conduct and public representations — not its preferred self-description — determine the classification. Researchers should also note that the term "carrier" appears in admiralty and maritime contexts with a specific statutory meaning under COGSA (the Carriage of Goods by Sea Act), which imposes its own liability framework distinct from common law common carrier doctrine.
Core Elements
Courts and commentators have consistently identified three elements that establish common carrier status:
1. Regular business or calling: Transport must be the entity's ordinary occupation, not an incidental or one-time activity.
2. Public offer: The carrier holds itself out to serve the general public or a definable segment of it, not just selected parties.
3. Compensation: The service is offered for hire. Gratuitous transport is analyzed under different bailment principles.
Why It Matters in Research
Researchers working in the Law Mind corpus will encounter common carrier doctrine across multiple bodies of law — tort, contract, bailment, admiralty, administrative, and constitutional — and the applicable rules shift significantly depending on which body of law governs.
The liability standard is the most important variable. At common law, carriers of goods were treated as virtual insurers; the recognized exceptions were narrow and strictly construed. Courts in the nineteenth century and early twentieth century were largely hostile to carrier attempts to limit liability by contract. This hardened rule softened over time as federal and state legislatures intervened — the Carmack Amendment federalized liability limitations for interstate rail and motor freight, and COGSA created a package-limitation regime for ocean carriage. Historical sources that state the common carrier's "absolute" liability should be read with awareness that this absolutism was being qualified even as those sources were written.
The passenger versus cargo distinction is critical. The heightened duty of care for passengers — often described as the "utmost care" or "highest degree of care" standard — persists in modern tort law and is distinct from the near-insurer rule applicable to goods. Researchers using historical treatises will find these two strands discussed together but governed by different doctrines.
Jurisdictional treatment of who qualifies as a common carrier has shifted with technology. The extension of common carrier obligations to new industries (telegraph, telephone, broadband) has each been contested; historical dictionary definitions will not anticipate these disputes. Corpus research on modern carrier regulation requires moving beyond the common law treatise tradition into administrative law and federal statutory sources.
Historical Dictionary Support
Black's Law Dictionary and Bouvier's Law Dictionary are in close agreement on the core definition: a common carrier is one whose regular business or calling is to carry chattels (and persons) for all who choose to employ and pay. Both sources draw directly on Schouler's treatise on Bailments, and both treat the concept as rooted in the law of bailment — which signals to the researcher that the common carrier was historically analyzed within private law, not public law or regulation.
Bouvier is more expansive on examples, explicitly listing stagecoach proprietors, omnibus proprietors, railroad and street railway companies as paradigmatic cases. This reflects the state of transport technology at the time of writing and is useful for placing historical cases in context.
Black's notes that California's Civil Code extended the definition to carriers of messages (excluding telegraphic messages), illustrating how states were actively legislating the boundaries of the category rather than leaving it entirely to common law development. This is a point the historical dictionaries capture but do not emphasize: the common carrier category was simultaneously a common law construct and a regulatory target, and the two tracks do not always align.
Neither source adequately addresses the limitation-of-liability question — a significant gap, since by the late nineteenth century the enforceability of carrier contracts limiting liability was already a major litigation front. Researchers relying solely on these definitions will miss the contractual and statutory modifications that were already eroding the absolutist liability picture the definitions imply.
Jurisdictional Note
Federal law governs most interstate common carrier liability through statutes such as the Carmack Amendment (surface freight) and COGSA (ocean carriage), largely preempting state common law in those domains. Intrastate carriers and passenger liability for injuries often remain subject to state law, producing variation in the applicable standard of care. Some states have codified the heightened passenger duty; others have moved toward ordinary negligence standards.
Encyclopedia Cross-Reference
Common Carrier Liability (Airlines, Railroads, Buses) — Torts & Personal Injury Encyclopedia (torts_52)
Carrier Liability, Package Limitation, and the Fair Opportunity Doctrine — Military, Veterans & Admiralty Law Encyclopedia (military_51)