Distinguished from flotsam and ligan and part of the maritime law principles of general average.
William Blackstone, at paragraph 292 of his Commentaries on the Laws of England, Book I, wrote:
"... in order to constitute a legal wreck, the goods must come to land. If they continue at sea, the law distinguishes them by the barbarous and uncouth appellations of jetsam, flotsam and ligan.
"Jetsam is where goods are cast into the sea and there sink and remain under water.
"Flotsam is where they continue swimming on the surface of the waves.
"Ligan is where they are sunk in the sea, but tied to a cork or buoy in order to be found again."
Jestam resembles but is not the same as things jettisoned overboard. Jetsam is by definition things jettisoned but things jettisoned do not become jetsam unless they are recovered from underwater.
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