neutrality, in international law, status of a nation that refrains from participation in a war between other states and maintains an impartial attitude toward the belligerents. Neutrality is not to be confused with neutralism, or nonalignment, under international law.
At the opening of hostilities, a nonbelligerent state generally issues a proclamation of neutrality. It is then the duty of the neutral power to observe strict impartiality in its relations with the warring nations. However, absolute neutrality is not always the reality, and the terms benevolent and hostile imply the sympathy of a neutral for one or other of the belligerents. The duty of the belligerent is to respect neutral territory (land and air) and neutral territorial waters (see waters, territorial). Switzerland, neutralized by the Congress of Vienna (1815), has stood as an example of a perpetually neutral state. Temporary neutrality flows from the unlimited sovereignty of the state, which allows it freely to decide its position in time of war and voluntarily to abstain from participation.
Neutral duties and rights were codified or incorporated in treaties and thus became part of international law. The Declaration of Paris (1856) standardized certain laws of neutrality (see Paris, Declaration of); the Declaration of London (1909) codified certain principles of neutrality with regard to maritime law (see London, Declaration of). At the Second Hague Conference (1907), neutral rights and obligations were defined in two conventions. The general neutrality convention, after declaring neutral territory inviolable, laid down regulations for neutral states and listed acts that should not be regarded as favoring one of the belligerents. The convention on neutrality in naval war, which was fuller, elaborated upon the duties of neutrals but did not incorporate rules for contraband and blockade.
In World Wars I and II, violations of neutrality by both sides were frequent, and attempts were made to justify the action by assertions that changed methods of warfare warranted changes in the observance of international law. When the League of Nations was established, it was generally recognized that member states could not be neutral in any dispute in which the League called upon them to intervene. The United States, which was not a member, asserted its intention to remain aloof from all wars and adopted (1935) the Neutrality Act. The United Nations, unlike the League, includes all the major world powers. Their obligations under the charter to restore and maintain the peace preclude neutrality, and neutral states, such as Switzerland, cannot become active members. The Geneva Conventions of 1949 provide a role for neutrals in the administration of prisoner-of-war agreements.
The 1794 Neutrality Act forbids U.S. citizens from taking part in military action against any country with which the United States is not at war. Enforcement of the act has been highly selective, however, with technical reasons usually offered for failure to prosecute. The United States has not declared war on anyone since World War II and has thus been legally neutral throughout such episodes as the Korean War, the Bay of Pigs invasion of Cuba (1961), and the Vietnam War. U.S. citizens have also often fought under the flags of other nations.
See E. Karsh, Neutrality and Small States (1988); J. M. Gabriel, The American Conception of Neutrality After 1941 (1989).