During times of war, belligerent states may attempt to interfere with maritime commerce to prevent ships from carrying goods that will aid the war effort of an opponent. After ships are captured and brought to a friendly port, a local tribunal called a PRIZE COURT will determine the legality of the seizure, or the destruction of the vessel and cargo if the vessel cannot be sailed to a friendly port. The body of customary INTERNATIONAL LAW and treaties that determines the appropriateness of such actions is referred to as prize law.
Prize law has not been completely consistent in its development because the tribunals that rule on the seizure of the vessel are national tribunals and may reflect the interests of the belligerent state in interdicting the enemy war effort. The expanding scope of warfare and the concept of total war have also blurred the distinction between vessels subject to capture as a prize of war and those that are exempt. Some basic rules remain, however. All vessels of an enemy state are subject to seizure at any time by an opposing belligerent. Warships may be sunk immediately, and private merchant vessels are to be taken to a friendly port, if possible, for adjudication by a prize court. A neutral vessel on the high seas or in a belligerent's territorial sea may be stopped and searched, if it is suspected of carrying contraband, and may be condemned as a prize of war if any is found. Finally the right of coastal fishing vessels of any state to be free from seizure while plying their trade is almost universally recognized.