Introduction
The Law of Blockade and Prize Courts is a crucial component of the Law of Naval Warfare, which governs the conduct of hostilities at sea. These principles regulate how belligerent states may lawfully restrict enemy trade and capture vessels during armed conflict while safeguarding neutral rights. The law of blockade restricts access to enemy coasts to weaken their war potential, while prize courts adjudicate the legality of captured ships and goods. Both systems aim to balance military necessity with freedom of navigation and neutral commerce, forming part of the broader framework of International Humanitarian Law (IHL) and the Law of the Sea.
I. Law of Blockade
1. Meaning and Definition
A blockade in international law refers to the belligerent act of preventing access to or departure from the enemy’s ports or coastlines by the use of naval forces. The aim is to weaken the enemy’s economy and war effort by cutting off supplies, reinforcements, and trade routes.
According to the Oxford Manual of Naval War (1913):
“A blockade must be declared and notified and maintained by a force sufficient to prevent access to the enemy’s coast.”
Thus, it is a coercive measure used during armed conflict and distinct from peacetime embargoes or sanctions.
2. Historical Evolution
The practice of blockade dates back to the 17th century and was prominently used during the Napoleonic Wars, American Civil War, and World War I and II. Initially, blockades were often paper blockades, meaning declared but not effectively enforced. This led to criticism and the need for codified rules.
Key developments include:
- Declaration of Paris (1856): First codification abolishing privateering and establishing that blockades must be effective to be binding.
- London Declaration concerning the Laws of Naval War (1909): Detailed the conditions under which a blockade could be considered legal.
- San Remo Manual on International Law Applicable to Armed Conflicts at Sea (1994): Modern interpretation aligning blockade law with humanitarian principles.
3. Legal Requirements of a Valid Blockade
Under international law (particularly the 1909 London Declaration and the San Remo Manual), a blockade must satisfy the following conditions:
a. Declaration and Notification
The blockading state must declare the blockade formally, specifying:
- The geographical limits of the blockaded area.
- The commencement date.
- The period of grace allowed for neutral ships to leave.
This must be notified to neutral states and the enemy.
b. Effectiveness
The blockade must be maintained by a sufficient naval force capable of preventing access to the enemy’s coast. A mere declaration without enforcement is invalid.
c. Impartiality
The blockade must be applied impartially to ships of all nations—no selective enforcement is allowed.
d. Proportionality and Humanity
The blockade should not aim to starve the civilian population or deny access to essential humanitarian supplies, as per Article 102 of the San Remo Manual.
e. Termination
The blockade ceases to exist if:
- The blockading force is withdrawn.
- The area under blockade is captured.
- The blockade is lifted by official declaration.
4. Breach of Blockade
A neutral vessel that attempts to enter or leave a blockaded port without permission is considered to have breached the blockade and is liable to capture and confiscation. However, vessels unaware of the blockade or caught due to distress are exempt.
Case Law: UN Charter and Its Principles
- The Franciska Case (1855): A vessel captured while trying to breach the blockade was condemned as a lawful prize.
- The Peterhoff (1866): The U.S. Supreme Court upheld seizure of a ship suspected of running the Confederate blockade during the American Civil War.
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Also Read:
II. Prize Courts
1. Meaning and Purpose
A Prize Court is a judicial body established by a belligerent state to determine the legality of captures made at sea during armed conflict. It decides whether captured ships and cargoes are lawful prizes or must be released.
Prize law thus forms the judicial mechanism for enforcing the law of blockade and maritime warfare.
2. Jurisdiction and Procedure
- Prize courts are national courts, not international tribunals.
- They derive their authority from national legislation but must follow customary international law.
- The captured vessel is brought to a port of the capturing state, where the court determines:
- Whether the capture was lawful.
- Whether the goods were contraband.
- Whether neutral rights were violated.
If the seizure is upheld, the vessel and goods become property of the capturing state; if not, they are released and compensation may be awarded.
3. Basis of Jurisdiction
Prize courts operate on the principle of jurisdiction over the res (thing) — meaning the captured vessel or goods must be physically within the court’s control.
Case: The Zamora (1916) – The British Prize Court emphasized that captures must conform to international law; even wartime necessity does not override legality.
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4. Key Functions
- Determine legality of capture under international law.
- Protect neutral trade and ensure compliance with blockade rules.
- Prevent arbitrary or excessive seizure by naval forces.
- Enforce rights related to contraband, enemy property, and breach of blockade.
III. Contraband and Blockade in Prize Adjudication
Prize courts often examine whether goods constitute contraband—items useful for war such as weapons, ammunition, and military supplies.
Under the London Declaration (1909), contraband was classified as:
- Absolute contraband (military use only),
- Conditional contraband (civilian or military use), and
- Free goods (purely civilian).
If a neutral vessel carries contraband knowingly to the enemy, it may be seized and condemned.
Case: The Nereide (1815) 13 U.S. (9 Cranch) 388 – The U.S. Supreme Court held that neutral goods on an enemy vessel are protected, maintaining balance between belligerent rights and neutral commerce.
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IV. Modern Developments
- The UN Charter (1945) restricts the use of force, making traditional wartime blockades rare.
- UN Security Council–authorized blockades (e.g., Iraq–Kuwait, 1990) are considered lawful under Chapter VII actions.
- The San Remo Manual (1994) reaffirmed humanitarian limits—blockades must not deny civilians food or medical supplies.
- Contemporary practice includes naval interdiction operations and maritime embargoes under collective security mandates.
V. Criticisms and Humanitarian Concerns
- Impact on civilians: Blockades often lead to humanitarian crises (e.g., Yemen, Gaza).
- Neutral state rights: Neutral shipping and commerce suffer unintended consequences.
- Ambiguity in enforcement: The line between legal blockade and economic warfare is blurred.
- Lack of international oversight: Prize courts are national, not global, raising impartiality concerns.
Conclusion
The Law of Blockade and Prize Courts represents the intersection of military necessity, economic warfare, and humanitarian protection. While rooted in the practices of earlier naval wars, modern interpretations emphasize legality, proportionality, and civilian protection. As maritime conflicts evolve, especially with hybrid warfare and sanctions, the principles of blockade and prize adjudication continue to adapt—anchored by international law’s enduring aim to limit suffering and preserve justice at sea.