How Prize Law Could Apply to the U.S. Blockade on Iran

Some analysts have recently raised the possibility of applying prize law to captured ships during armed conflict. Prize law is the body of maritime law and the law of armed conflict that applies to captured neutral or enemy merchant vessels. Prize law applies to civilian merchant vessels, distinct from enemy warships or aircraft, which automatically become booty of war when captured. Prize law only applies during armed conflict, making it distinct from routine maritime interdictions or sanctions enforcement, which can occur outside armed conflict and are not necessarily belligerent acts. Eight specific grounds make a neutral state’s vessel capturable, including breaching a blockade, carrying contraband, and resisting visit and search. Contraband consists of goods destined for an enemy of a belligerent and susceptible to use in armed conflict, a definition that was has not been broadly applied since World War II. According to U.S. policy, a blockading state has the right to stop vessels bound to or from blockaded ports anywhere on the high seas and apply prize law. Although the U.S. has recently interdicted other Iran-linked vessels outside the Strait of Hormuz, the U.S. has invoked maritime interdiction and sanctions enforcement for those interdictions, not for blockade violations.

Although the Touska was a sanctioned vessel, the U.S. has explicitly invoked the blockade breach ground for the Touska, perhaps as a warning to other ships not to breach the blockade, or as a signal that the blockade is effective and being enforced. This justification also opens the door for the application of prize law. Once vessels are captured, they can be escorted to a port under belligerent jurisdiction for inspection and adjudication by a prize court. That court would determine whether the capture was lawful. If so, the court may condemn the vessel and cargo as prize, and award title to the capturing state.

Why Prize Law Could Apply to the Blockade-Running Iranian Ship M/V Touska

While the Touska’s current location is not publicly known, the United States appears to be following appropriate procedure. In the U.S., federal district courts have jurisdiction as prize courts, but no prize courts have been established since 1956. If adjudication is impracticable, a state may destroy the prize after all possible measures are taken to ensure the safety of its passengers and crew.

The Strategic Case for the Use of Prize Law in the Iran War

It is unclear whether the United States will apply regular sanctions enforcement procedures to the Touska, which would produce a similar practical result of giving the United States title to the ship and its cargo. The United States may wish to signal to its adversaries that it will aggressively enforce its rights as a belligerent in naval warfare. Invoking prize law would also send a strong message to non-sanctioned, neutral merchant ships bound for Iranian ports not to violate the U.S. blockade anywhere in the world. Prize law enforcement might help convince flag of convenience states, which sometimes sell their flags to illicit vessels, to stop doing so rather than be drawn into a complicated legal process within a messy war. Prize courts could also force flag state officials and ship owners to appear in court, enabling discovery and unraveling the complex—and often corrupt—business operations that underlie adversary war efforts. It would establish the architecture for prize law enforcement in a future conflict with China.

How Prize Law Might Shape Markets – and Future Conflict with China

Prize law could also be a useful tool for the United States in any future conflict with China. China is actively building dual-use merchant vessels that can also be used for military purposes. China has the world’s largest merchant fleet by tonnage, and is heavily dependent on seaborne energy and materials. Prize law would allow the capture of Chinese merchant ships wherever they are located, beyond neutral territory, providing a legal framework that could disrupt China’s dual-use strategy.

The fate of the Touska will ripple through global insurance markets and affect the risk exposure of merchant ships in wartime. Whether the centuries-old doctrines of prize and booty will reemerge could also shape the future of conflict. Iran’s own shipping restrictions on the Strait of Hormuz do not comply with international law. However, Iran may choose to invoke the language of prize and booty in its interdictions of vessels, complicating U.S. messaging about the legality of its own actions. Application of prize law in the current conflict between the United States and Iran could also open the door for China to apply prize law against the United States—a dangerous proposition for U.S. and neutral merchants in any war with China. The fate of the Touska is one to watch. If the U.S. invokes prize law for the Touska and sets up a prize tribunal, it could rebuild the institutional muscle memory it needs for future conflict. It could also give U.S. adversaries the opportunity to flex.