Prize Rules

Prize rules or cruiser rules govern the taking of prizes: vessels captured on the high seas during war. They are intertwined with the blockade rules.

Customary rules were originally laid down in the days of sailing ships. These were supplemented by various international agreements including the Declaration of Paris (1856) and the Hague Conventions (1899 and 1907) and other naval agreements during the 20th century. Although these rules are still part of the laws of war, changes in technology like the radio and the submarine made them redundant between belligerents during World War I and World War II. Still, the Nuremberg Tribunal found that these rules were still applicable to neutral merchant shipping.

Prize rules state that passenger ships may not be sunk, crews of merchant ships must be placed in safety before their ships may be sunk (life boats are not considered a place of safety unless close to land), only warships and merchant ships that are a threat to the attacker may be sunk without warning.