Prize Cases

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Prize Cases, 67 U.S. 635 (1863).

Facts: During a blockade of Southern ports instituted by Pres. Lincoln before Congress declared war on the Confederacy, Union ships seized vessels and cargoes of foreign neutrals. The property was then condemned by federal court order. The ship and cargo owners appeal.

Issue: May the Pres., acting without a congressional declaration of war, institute a blockade of southern ports that neutrals are bound to respect?

Holding: Yes.

Judgment: Decrees of condemnation affirmed.

Dissent: Congress alone can determine whether war exists or should be declared, and until they have acted, there can be no penalty of confiscation for the acts of others with whom the owner had no concern. The congressional ratification of the seizures is invalid as an ex post facto law.


  • The law of nations requires that a war must exist de facto in order to legitimate the capture of a neutral vessel or property on the high seas. Congress had not declared a ward when the Pres. acted, but it had previously authorized the Pres. to call out the militia and use military force to resist invasion and suppress insurrection against the government of a state or of the US. He need not wait for special legislative authority to respond to such challenges.
  • The determination of the extent of an armed challenge to the US rests with the President. His proclamation of a blockade is, itself, adequate evidence to the Court that a state of war existed which demanded the use of such force as the Pres. deemed necessary.
  • In this case, the legislature subsequently ratified the President’s actions.