The Paris Declaration Respecting Maritime Law of 16 April 1856 was issued to abolish privateering. It regulated the relationship between neutral and belligerent and shipping on the high seas introducing new prize rules.
The major points in the declaration were:
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The present Declaration is not and shall not be binding, except between those Powers who have acceded, or shall accede, to it.
On the conclusion of the Treaty of Paris, which was signed on 30 March 1856, putting an end to the Crimean War (1853–1856), the plenipotentiaries also signed this declaration at the suggestion of Count Walewski, the French plenipotentiary. The declaration is the outcome of a modus vivendi signed between France and the United Kingdom in 1854, originally intended for the Crimean War. These two powers had agreed that they would not seize enemy goods on neutral vessels nor neutral goods on enemy vessels. The belligerents had also agreed that they would not issue letters of marque, which they had not done during the war. At the close of this war the principal states of Europe concluded that private armed ships, maintained at private cost for private gain, and often necessarily for a long time beyond the reach of the regular naval force of the state, could not be kept under proper control. The Declaration of Paris confirmed these rules and added to them the principle that blockades, in order to be obligatory, must be effective.
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.
Ultimately, 55 states ratified the Declaration, including the United Kingdom, Austria, 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.