Definition
Lex Rhodia de Jactu (literally, "the Rhodian law on jettison") is the ancient maritime legal principle establishing that when cargo is deliberately thrown overboard to lighten a vessel in distress and save the ship, the resulting loss must be shared proportionally among all parties with an interest in the voyage — shipowners and all cargo owners alike — rather than falling solely on the owner of the goods sacrificed. The principle is the historical foundation of what modern maritime law calls general average.
The rule operates on a logic of equitable contribution: where a deliberate sacrifice benefits all interests in a common maritime venture, all who benefit must contribute to the loss. The cargo owner whose goods were jettisoned does not bear the entire burden; those whose property was saved by the sacrifice contribute in proportion to the value of what they saved.
Common Confusion
Lex Rhodia de Jactu is frequently treated as synonymous with general average in modern usage. The distinction matters for researchers: Lex Rhodia de Jactu refers specifically to the ancient Roman-Rhodian rule governing jettison (throwing cargo overboard), which was one particular application of the broader principle. General average is the modern doctrine that has expanded that principle to cover a wider range of voluntary sacrifices and extraordinary expenditures made for the common safety of a maritime venture. Using the terms interchangeably in historical sources earlier than the codification of modern average rules can produce analytical error.
Why It Matters in Research
This term is a navigational marker more than a living legal rule. Researchers will encounter Lex Rhodia de Jactu primarily in three contexts: Roman law scholarship, the history of maritime law, and the doctrinal genealogy of general average.
In Roman law sources, the rule appears in the Digest at D. 14, 2 (the lex titulus on the Rhodian law), where it is one of the clearest examples of Rome explicitly borrowing from a foreign legal tradition. Researchers working in the civilian tradition or comparative law will find the Digest passage the authoritative primary source.
In maritime law history, the term appears in treatises tracing the origins of general average. Nineteenth-century sources, including Bouvier's, treat it as the founding authority for the principle that voluntary sacrifice for common benefit creates a right of contribution. This genealogical treatment persists into early twentieth-century admiralty scholarship, so researchers reading those sources will see Lex Rhodia de Jactu invoked where a modern author would simply write "general average."
The key trap in historical sources is scope creep. Bouvier and similar authorities sometimes use Lex Rhodia de Jactu loosely to cover the entire body of Rhodian maritime custom as received by Rome, not just the jettison rule specifically. A passage citing "the Rhodian law" may be invoking a broader customary maritime framework rather than the jettison rule alone. Context and the specific Digest citation (D. 14, 2) are the most reliable anchors.
For corpus researchers: the term connects directly to general average doctrine, to York-Antwerp Rules scholarship (the modern codification of general average contributions), and to Roman law sources on maritime commerce. It rarely appears in primary legal materials after the early modern period; by the nineteenth century, practicing lawyers and courts were using "general average" in its place.
Historical Dictionary Support
Bouvier's Law Dictionary entry, though truncated in the available source material, conveys the essential structure accurately: the Roman law adopted Rhodian maritime custom where it did not conflict with Roman law; the jettison rule required shared contribution among vessel and cargo owners when goods were thrown overboard to save the ship. The Digest reference at D. 14, 2, 9 is the correct citation and its inclusion signals that Bouvier treated this as a civilian doctrine with a traceable textual basis rather than mere custom.
What historical legal dictionaries, including Bouvier's, tend to underemphasize is the degree to which the "Rhodian law" received by Rome was already a reconstruction — Rome's jurists were applying a principle attributed to Rhodian custom rather than enforcing an intact foreign code. Modern Roman law scholarship (Hunter's Roman Law, cited by Bouvier, reflects the nineteenth-century view) treats this reception as genuine legal borrowing, but the original Rhodian texts do not survive. Researchers should be cautious about treating citations to "the law of Rhodes" as references to a recoverable written code.
Jurisdictional Note
As a historical Roman-law doctrine, Lex Rhodia de Jactu has no current jurisdictional application. Its descendant, general average, is today governed in most maritime jurisdictions by the York-Antwerp Rules (periodically revised, most recently in 2016), incorporated by contract into bills of lading worldwide, alongside domestic admiralty statutes where applicable.