The Prize Cases

Supreme Court of the United States · 1863 · Constitutional Law

67 U.S. (2 Black) 635 (1863)

Updated July 29, 2026

Constitutional LawWar PowersPrizeBlockadeCivil WarCommander in Chiefprize lawbelligerency

Facts

After the outbreak of large-scale armed resistance by the Confederate States, the President issued proclamations announcing a blockade of ports in states whose inhabitants were in rebellion. United States naval forces seized the Amy Warwick, the Crenshaw, the Hiawatha, and the Brilliante, together with cargoes, on the ground that they were attempting to breach that blockade or were otherwise subject to capture as prize. Claimants argued that no war legally existed absent a congressional declaration and that the President therefore lacked power to impose a blockade producing prize consequences. The captures at issue occurred in the course of suppressing the insurrection and enforcing the President's blockade measures.

Issue

When states and their inhabitants wage organized armed rebellion against the United States, may the President, without a formal declaration of war by Congress, treat the conflict as war for purposes of blockade and maritime capture? Relatedly, are vessels captured for violating such a blockade subject to condemnation as prize?

Rule

War may exist de facto when the regular course of justice is interrupted by organized, hostile resistance of such magnitude that the government must meet it with military force. In such a civil war, the President is bound to accept the challenge without waiting for Congress, and as Commander in Chief may institute a blockade of insurgent ports; courts must recognize the belligerent status and apply the law of prize to captures made in enforcing that blockade.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

An organized armed movement seizes multiple federal forts along the Gulf Coast, controls several ports in Louisiana and Mississippi, fields a navy of converted merchant ships, and engages federal troops in sustained battles for months. Before Congress meets, the President orders a naval blockade of the insurgent ports, and a cargo vessel owned by Maple Shoals Shipping is captured off Biloxi while attempting to run the blockade.

Is the capture most likely valid?

Explanation. The majority held that war may exist de facto when organized, large-scale hostilities force themselves upon the nation. In that situation, the President does not initiate war but must meet it, and may recognize the belligerent condition and institute a blockade of insurgent ports. Courts must treat such captures under the blockade as valid prize seizures if otherwise lawful.