Freedom of Navigation

Freedom of navigation (FON), is a principle of customary international law that, apart from the exceptions provided for in international law, ships flying the flag of any sovereign state shall not suffer interference from other states. This right is now also codified as article 87(1)a of the 1982 United Nations Convention on the Law of the Sea. Not all UN member states have ratified the convention; notably, the United States has signed, but not ratified the convention.

Until the early modern period, international maritime law was governed by customs that were sometimes codified: as for example in the 14th-century Catalan Consulate of the Sea (Catalan: Consolat de mar; Italian: Consolato del mare; also known in English as the Customs of the Sea). Such customs governed cases in prize courts about the capture of goods on the high seas by privateers. This rule can be distilled from the Consolato (and other contemporary codes): "enemy goods can be captured on neutral ships and neutral goods are free on board enemy's ships." The first part of the rule implies that neutral shipping is not inviolable in time of war, but the second part implies that goods of neutral owners are. The former contradicts what is now called "freedom of navigation." The doctrine, which will be referred to as the consolato rule for short, was long observed by England (later Great Britain), France, and Spain, as major naval powers.

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