The Declaration did not as such make privateers into a new category of international criminals, but rather made it a treaty obligation of states that they refrain from commissioning privateers in the first place. Most states normally treated foreign privateers as pirates in any case.
Numerous states ratified this declaration, including the United Kingdom, Austria-Hungary, France, Prussia, Russia, Sardinia and the Ottoman Empire. This treaty established maritime law among the major powers of Europe. It represented the first multilateral attempt to codify in times of peace rules which were to be applicable in the event of war. This declaration bound only its signatories when at war with each other, and lets them free to use privateers when at war with other states.
The United States, which aimed at a complete exemption of non-contraband private property from capture at sea, withheld its formal adherence in 1857 when its "Marcy" amendment was not accepted by all powers, chiefly as a result of British influence. The US was also keen on maintaining privateers. It argued that, not possessing a great navy, it would be obliged in time of war to rely largely upon merchant ships commissioned as war vessels, and that therefore the abolition of privateering would be entirely in favour of European powers, whose large navies rendered them practically independent of such aid. All other maritime states acceded to the declaration except Spain, Mexico and Venezuela.
In 1861, during the American Civil War, the United States declared that it would respect the principles of the declaration during hostilities. The same was done during the Spanish-American War of 1898, when the United States Government affirmed its policy of conducting hostilities in conformity with the dispositions of the declaration. Spain too, though not a party, declared its intention to abide by the declaration, but it expressly gave notice that it reserved its right to issue letters of marque. At the same time both belligerents organized services of auxiliary cruisers composed of merchant ships under the command of naval officers.
Some of the questions raised by this declaration were clarified by the 1907 Hague Convention.