Letter of marque

In the days of fighting sail, a letter of marque and reprisal was a government license authorizing a person (known as a privateer) to attack and capture enemy vessels and bring them before admiralty courts for condemnation and sale. Cruising for prizes with a letter of marque was considered an honorable calling combining patriotism and profit, in contrast to unlicensed piracy, which was universally reviled. In addition to the term lettre de marque, the French sometimes used the term lettre de course for their letters of marque. "Letter of marque" was sometimes used to describe the vessel used: a "letter of marque" generally refers to a lumbering square-rigged cargo carrier that might pick up a prize if the opportunity arose. A "privateer" was a fast and weatherly fore-and-aft-rigged vessel heavily armed and heavily crewed, intended exclusively for fighting.

A "letter of marque and reprisal" would include permission to cross an international border to effect a reprisal (take some action against an attack or injury) authorized by an issuing jurisdiction to conduct reprisal operations outside its borders.