Definition
The deliberate throwing overboard of cargo, equipment, or other property from a vessel in a situation of extreme peril, done to lighten the ship and preserve the safety of the vessel and remaining cargo. The term carries a double meaning in maritime law: it refers both to the act of casting goods overboard and to the goods themselves so discarded.
Jettison is not mere loss or accident — it is a voluntary, intentional sacrifice made under necessity. This distinction is legally significant because a valid jettison triggers the doctrine of general average, entitling the shipowner and the parties whose cargo was sacrificed to contribution from those whose property was saved by the act.
Common Language
Modern common usage (Wiktionary): Items that have been or are about to be ejected from a boat or balloon; also the action of jettisoning such items. In everyday use, the word has extended broadly to mean discarding anything — a plan, a policy, a person — considered burdensome or no longer useful.
Historical common usage (Webster's 1913): "The throwing overboard of goods from necessity, in order to lighten a vessel in danger of wreck."
The ordinary modern sense of the word has drifted far from its legal home. Colloquially, one "jettisons" a business strategy or a political position. In maritime law, jettison retains strict technical requirements: the act must be voluntary, made under genuine peril, and carried out for the common safety. Casual or accidental loss of cargo does not qualify, and the legal consequences — principally the right to general average contribution — attach only when those elements are satisfied.
Common Confusion
Jettison is sometimes conflated with jetsam, flotsam, or lagan, which are categories of maritime property defined by how goods came to be in the water and whether they remained afloat, sank, or were marked for recovery. Jetsam specifically refers to goods deliberately cast overboard (i.e., the product of jettison) that have sunk or washed ashore. The act is jettison; the resulting goods, once in the water, become jetsam. A researcher tracking ownership claims to recovered cargo must distinguish among these terms carefully, as rights of recovery and salvage differ across categories.
Core Elements
For a jettison to be legally effective and to support a general average claim, the traditional requirements are:
1. Voluntariness. The sacrifice must be a deliberate human decision, not an accident or act of nature.
2. Necessity. The peril must be real and immediate — not speculative or minor. The sacrifice must be reasonably required for the common safety.
3. Common benefit. The purpose must be to save the ship and its remaining cargo, not merely to benefit one party's interest.
4. Good faith. The master or person directing the act must exercise reasonable judgment under the circumstances.
Where these elements are absent — particularly voluntariness and necessity — the loss falls outside general average and the owner of the sacrificed cargo bears the loss alone or looks to other remedies.
Why It Matters in Research
Researchers working with maritime sources prior to the late nineteenth century will encounter jettison primarily in the context of general average disputes, which produced a substantial body of admiralty case law and commercial practice. The doctrine's scope — which cargo qualifies, how contribution is calculated, what counts as peril sufficient to justify the act — shifted considerably over time and varied by trade route, flag, and applicable rules.
A critical research trap: not all historical sources treat jettison of deck cargo and jettison of hold cargo identically. Deck cargo, particularly when loaded in violation of custom or agreement, was sometimes excluded from general average contribution in older practice, meaning the owner of jettisoned deck cargo might receive nothing. This distinction appears in admiralty cases and treatises but is not always flagged in general legal dictionaries.
The York-Antwerp Rules — periodically revised starting in 1890 — govern general average in international shipping contracts and represent the operative framework in most modern commercial contexts. Researchers moving from common law admiralty sources to modern practice should note that the Rules may displace or modify the common law rules on what constitutes a valid jettison and how contribution is calculated.
For corpus researchers: jettison as a standalone legal topic appears less frequently in nineteenth-century American sources than in English maritime law texts and treatises. American admiralty practice borrowed heavily from English sources, but state commercial law and insurance cases occasionally addressed jettison claims through a different doctrinal lens than admiralty courts.
Historical Dictionary Support
Black's (1st and 2nd Ed.) agree on the core definition and both emphasize the dual usage — act and object — while requiring extreme danger and the purpose of lightening the ship. The 2nd Edition adds case citations that are useful navigational anchors for admiralty research. Both editions gesture at the carrier's privilege to sacrifice cargo under conditions of extreme peril, treating this as an established rule rather than a contested principle.
Bouvier's entry, as reproduced in the source material, does not directly address jettison in the maritime sense; the available excerpt concerns court orders for preservation of property pending litigation — likely a neighboring entry or a cross-reference artifact. This is a signal to researchers that Bouvier's may be less useful for jettison specifically and that Black's and admiralty-specific treatises are the more reliable starting points.
What the historical dictionaries do not address: the York-Antwerp Rules, the treatment of deck cargo, and the distinction between jettison for general average purposes and other voluntary sacrifices (such as scuttling or deliberate grounding). These gaps are not surprising given the dates of publication but are material for anyone moving between historical and modern sources.
Jurisdictional Note
In the United States, jettison and general average are primarily governed by federal admiralty jurisdiction. State law plays a limited role. International shipping contracts frequently incorporate the York-Antwerp Rules by express agreement, which may alter the common law framework substantially. Researchers working with English sources should note that English admiralty practice, while historically influential on American law, developed along a parallel rather than identical track.