The term "neutrality" is generally used to designate the legal status under international law of a sovereign state that seeks to avoid involvement in an armed conflict between belligerent states, protect its rights, and exercise its responsibilities as a neutral. Consequently, a neutral state under international law or practice asserts that it has the right to remain at peace and prohibit sovereign acts by belligerents within its jurisdiction, and also a responsibility to treat belligerents impartially. Customary international law, treaties, and relevant domestic legislation confirm such rights and responsibilities. A nation's sovereignty extends to its territory, its ships on the high seas, and the air space above its territory. These principles were, for the most part, reconfirmed in the late twentieth century by the Third United Nations Conference on the Law of the Sea (UNCLOS III) from 1972 to 1982. After reviewing the entire historical body of law related to maritime issues, the conference produced the UN Convention on the Law of the Sea. Among other things, the convention established the breadth of territorial seas and economic zones and guaranteed traditional rights of navigation on the high seas as well as overflight.
Neutral states may engage in all legal international intercourse; therefore, neutrality is not synonymous with isolation, nor should it be confused with neutralism or nonalignment, terms that refer to peacetime foreign policies of nations desiring to remain detached from conflicting interests of other nations or power groups. This concept of neutrality has its origins in western Europe after the rise of independent states following the Peace of Westphalia at the close of the Thirty Years' War in 1648.
Respect for, and acceptance of, neutrality as having any bearing in international law or practice developed slowly during the seventeenth and eighteenth centuries. At the time, Europe was in a state of anarchy and neutrals' rights were limited to what was acceptable to belligerents. The little advancement that did occur was largely the result of rivalry among states for trade and territory in the New World. Spain and Portugal's attempts to divide the New World between themselves, establish a monopoly of trade and colonization there, and close the seas to other nations was soon challenged by early writers on international law. In 1608 Hugo Grotius advanced the doctrine that since the seas could not be occupied, they could not become the property of any person or nation. Like the air, the seas were therefore the common property of all men. Although Spain and Portugal accepted this doctrine somewhat begrudgingly, it was firmly established by the end of the seventeenth century, and the notion of neutrality started to evolve among nations.
In general, restraints on trade revolved around the laws of blockade, the definition of contraband of war, the principle that free ships make free goods, and the right of neutrals to trade between the ports of belligerents. In all of these situations, the restraints on neutrals resulted from the obvious desire of belligerents to prevent their enemies from receiving war materials or other goods that may be needed in war. The law of blockade was an outgrowth of the law of siege in land warfare. Governments acknowledged the practice that a city or a place effectively besieged could be legally cut off from all outside help. When this principle was applied to ports, a blockade had to be effective in order for it to be legal; however, it was difficult, particularly during the age of sail, to seal a port completely. No precise definition of effectiveness was ever found, although an attempt was made in some commercial treaties to establish that a blockaded port had to be sufficiently guarded so as to render a ship "in imminent danger of capture" if it attempted to run the blockade.
The laws governing contraband of war have a long history. Under a late medieval code, Consolato del Mare, all goods destined for an enemy, in belligerent or other ships, were subject to seizure. Early in the seventeenth century, commercial treaties started to distinguish between contraband and noncontraband. The earliest example of this was the Anglo-Dutch Treaty of Southampton in 1625. Ordinarily, such treaties contained lists of goods under both categories, but uniformity in such lists was difficult, except that obvious materials of war were always considered contraband. The idea that free ships make free goods was associated with the issue of contraband. In essence, the concept meant that a ship's nationality determined the status of its cargo, and that enemy goods on a neutral ship, excepting contraband, would not be subject to capture on the high seas.
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