The jus or ius naufragii (right of shipwreck), sometimes lex naufragii (law of shipwreck), was a medieval custom (never actually a law) which allowed the inhabitants or lord of a territory to seize all that washed ashore from the wreck of a ship along its coast. This applied, originally, to all the cargo of the ship, the wreckage itself, and even any passengers who came ashore, who were thus converted into slaves. This latter custom disappeared before the jus naufragii came to the attention of lawmakers.

Right, God, and abolition

The theoretical basis for the law, in Christian (and presumably Islamic) countries, was that God must be punishing the doomed ship for the vice of the crew. The ship and its cargo had thus been taken from their rightful owners by an act of God and were fair game. Despite this, consistent attempts to abolish the practice are recorded over the course of more than a millennium.