Also known as: letters of marque · law of marque · letter of marque · letters of marque and reprisal
Written by attorneys · grounded in primary & secondary sources — see below
A constitutional grant of authority empowering Congress to commission private vessels to seize enemy property on the high seas during armed conflict. The power appears in the enumerated powers of Article I and is expressly withheld from the states.
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After war is declared, Congress passes a statute directing the President to issue letters of marque to qualified merchant captains. Miranda Morales, owner of a fast schooner, receives a commission and captures an enemy cargo ship on the high seas. The prize is condemned in federal court and the proceeds distributed according to the statute. The action rests on Congress's enumerated power to grant such commissions.
A coastal state legislature enacts a statute purporting to grant letters of marque to local fishing vessels. Mariam Mansour, a state official, issues the first commission and the vessel seizes a foreign freighter. Federal authorities arrest the crew and invalidate the commission. The state action violates the constitutional prohibition on state grants of marque.
A commissioned privateer brings a captured vessel into port. Mustafa Mahmoud, the prize master, petitions the district court for condemnation. The court examines whether the letter of marque was properly issued and whether the capture occurred on the high seas. The proceeding determines ownership of the prize under federal prize law.
The President revokes an outstanding letter of marque after hostilities cease. Monica Morgan, the holder, continues to seize vessels and claims the captures are lawful. Federal prosecutors charge her with unauthorized privateering. The revocation ends the legal authority previously granted by Congress.
A state port authority refuses docking to a federally commissioned privateer. Musa Mensah, the vessel owner, sues claiming the state is interfering with a federal war power. The court holds that the state may not obstruct execution of the federal marque authority.
An individual without a letter of marque attacks enemy shipping and is captured. Madison Meyers is tried by military commission for violating the law of war. The commission's jurisdiction rests on Congress's power to define offenses against the law of nations and to regulate captures at sea.
Congress holds the exclusive power to grant letters of marque and reprisal under Article I, Section 8. The Constitution expressly forbids states from issuing such commissions.
Supporting sources
No. A letter of marque is valid only during the period of authorized conflict. Once Congress or the President terminates the authority, further captures become unauthorized and subject to prosecution.
Supporting sources
States may not obstruct or regulate vessels operating under federal letters of marque. Such interference would conflict with Congress's enumerated war powers.
Supporting sources
…officers, and in the making of treaties. A third remains to be mentioned; the right of the legislature to declare war and grant letters of marque and reprisal.' "With these exceptions, the executive power of the United States is completely lodged in the President. This mode of construing the Constitution has indeed been recognized by Congress in…