War, Laws of

views updated Jun 11 2018


WAR, LAWS OF. The laws of war are the rules of international law that govern the conduct of war between nation-states, and are especially concerned with whether a use of force is allowed, when a state of war exists, the weapons and conduct of war, and the treatment of opponents, prisoners, neutrals, and noncombatants. They apply to the United States through enactments by Congress, the president, the Department of Defense, and specific commanders—as well as through the ratification of treaties including the Charter of the United Nations, and through those obligations of international custom binding according to the U.S. Constitution.

Early Limits on War

There have been limits on the conduct of war throughout military history. These limits persist even though they are frequently violated, often without punishment. The degree to which a nation complies with them is the degree to which that nation is perceived as civilized, just as compliance on the part of a nation's military is what distinguishes it as professional. Furthermore, in the twentieth century, principles of state and personal responsibility have led to the possibility of effective criminal enforcement.

Ancient laws of war dealt mostly with immunity from combat and with the commencement of hostilities. By custom and treaties, the city-states of ancient Greece respected truces, armistices, peace treaties, alliances, flags of truce and the immunity of heralds, truces to bury the dead, surrender conditions, and the inviolability of victory monuments. The neutrality of religious temples, the Olympic games and, sometimes, third-party states were ordinarily respected. Conformity to these rules was thought necessary to be civilized, to obey the gods, and to justify similar treatment from opponents.

The Roman iustum bellum required that attacks could not be made unless there had been a prior declaration of war or unless prior demands had not been satisfied. Roman law did not, of course, limit conquest, although the treatment of conquered lands and people was closely regulated.

Religion and manners were the sole limits on medieval warfare. Both Christianity and Islam placed limits on treatment of their faithful in war that did not apply to heretics or infidels. Both cultures evolved forms of chivalry that constrained the forms of battle and the treatment of prisoners, although such rules were often beneficial only to those with high rank. Neither could enslave a captured enemy of the same religion. The Christian church evolved a doctrine of just war and doctrines protecting noncombatants from death in war. These doctrines were reflected in canon law but not in national legal systems, which tended to follow the view associated with Niccolò Machiavelli and Carl von Clausewitz, that war is justified as a rational instrument of national policy, even for the purpose of conquest. Various attempts were made by popes and kings to improve the treatment of civilians in surrendered towns and to limit the horrors of war by banning devious or inhumane weapons, such as the crossbow or, later, the bayonet. While these attempts yielded no means of enforcement, still, armies often followed some humanitarian customs of war for the ancient reason of ease to the army, particularly by limiting looting.

The Seventeenth through Early Twentieth Centuries

The modern law of war was invented during the age of the English colonies in North America. During the Thirty Years' War (1618–1648), Dutch jurist and ambassador Hugo Grotius published On the Law of War and Peace, an extended and systematic argument that nations are bound by natural law to respect other nations, that they should only engage in wars justified by grounds that would be satisfactory as claims for legally cognizable harms, and that they must respect the rights of noncombatants. This argument gained much attention but slow acceptance.

During the American Revolution, the guiding principle was not a law of war but the customs of the armies and navies of Europe; however, these customs were often violated, as with the American habit of sharpshooting enemy officers. One custom that was honored was the execution of spies. The U.S. Army's Articles of War (1775) did, however, codify many customs, such as the requirements of uniforms and organization.

By the mid-nineteenth century, there was both more formal organization of the U.S. military and greater agreement about the rules. In the Mexican War, General Winfield Scott created military commissions to prosecute U.S. soldiers and Mexican civilians for violations of the rules of war.

The first codification of the law of war by the United States was General Order 100, issued at the direction of President Lincoln by General-in-Chief Henry Halleck, enacting the rules set forth in a report by Francis Lieber, a German-American law professor at Columbia College in New York. Entitled Instructions for the Government of Armies of the United States in the Field, it augmented the 1775 articles but went much further, setting humane standards for the handling and exchange of prisoners, the freeing of slaves, the treatment of people and property in occupied territory, and the treatment of opposing combatants. With the notable exception of Sherman's surprise bombardment of Atlanta, the union Army appears to have complied with Lieber's Code, and the Southern armies seem to have emulated it. The U.S. Supreme Court acknowledged it as federal law in Ex parte Vallandigham, 68 US 243 (1863).

Lieber's Code immediately influenced international law. Translated into German by Johann Bluntschli, it formed the basis of his Das Moderne Kriegsrecht (1866) and was reprinted whole in most international law texts for the next fifty years. Its terms and ideas influenced the European powers at the first Geneva Convention (1864) to agree to standards of treatment for wounded prisoners of war. International conferences at The Hague in 1899 and 1907 codified much of the Code regarding the definition of combatants and treatment of neutrals into the international laws of war.

The Crimean War, the U.S. Civil War, and the Franco-Prussian War all provoked codification of the laws of war. The Declaration of Paris of 1856 outlawed privateering, made naval warfare a matter for state professionals, and established clearer rules regarding blockades and the rights of neutral shippers. The Geneva Convention of 1864 drafted the first code for the treatment of the enemy's wounded. The 1868 Declaration of Saint Petersburg announced that the only legitimate use of war is to weaken an enemy's military, and it restricted the use of small explosive or incendiary projectiles. A convention at The Hague in 1899 rejected the use of expanding bullets and asphyxiating gasses.

While the great states of Europe negotiated and signed conventions, the United States was slow to do so, although it abided by these norms separately. Only during World War I did the U.S. agree to abide by the Declaration of Paris of 1856. The U.S. did not sign the convention of 1864, the declaration of St. Petersburg, the 1899 Hague Convention, or the first Geneva Convention. Even so, the Hague Conventions of 1899 and 1907 were both derived from Lieber's Instructions, which the United States reissued in 1898, and in 1914 the U.S. Army first compiled The Rules of Land Warfare, a handbook for soldiers in battle.

American interest in international regulation of law increased dramatically with the presidency of Theodore Roosevelt. In 1904 Roosevelt called a meeting under terms of the 1899 convention, seeking to codify and extend the earlier conventions. The resulting Second Hague Peace Conference ended in 1907 with fourteen treaties, setting forth standards for the commencement of hostilities, customs and duties of warfare on land and sea, and the standards of neutrality. The U.S. signed and ratified these conventions, making them the first significant international laws of war to be law in the U.S. through treaty. This was not the only method by which the laws of war became U.S. law, however, and in The Paquete Habana, 175 US 677 (1900), the U.S. Supreme Court had recognized that the customary international law of war was enacted into U.S. law by the Constitution.

World Wars I and II and Their Consequences

The horrors of World War I, including the widespread violation of earlier pacts, led interwar peace conferences toward attempts at the prevention of war and the limiting of inhumane tactics and weapons, but these efforts met with only moderate success. The 1923 Hague Convention, on the rules of aerial warfare, failed to achieve sufficient ratification to come into force. The Geneva Gas Protocol (1925) prohibited the use in war of asphyxiating, poisonous, or other gases and of bacteriological methods of warfare. The Geneva Conventions of 1929 detailed the treatment of prisoners of war and of the enemy sick and wounded. The Washington Disarmament Conference (1921–1922) and the Treaty of London of 1930 limited submarine warfare against noncombatant ships. Despite occasional breaches, it is notable that there was widespread compliance with these treaties in the subsequent world war.

The great exceptions to this tendency toward compliance were the peace treaties, commencing with the Bryan Treaties of 1913 and 1914, and the controversial Versailles Treaty of 1919, all of which promoted limits on the grounds for commencing war, including requirements for investigation, arbitration, and peaceful settlement of disputes. This process culminated in the Kellogg-Briand Pact of 1928.

Named for French foreign minister Aristide Briand and U.S. secretary of state Frank B. Kellogg, this initially bilateral treaty was eventually signed by nearly all of the nations then on earth, each renouncing war as an instrument of national policy and agreeing to settle all disputes by peaceful means. A surfeit of qualifications allowed wars in defense of the Covenant of the League of Nations, other military treaties, the Monroe Doctrine, and for self-defense. More damning, there was no mechanism for enforcement, and the treaty was ineffective as a prior restraint to aggression. It was, however, one of the key bases for trials after World War II on charges of waging aggressive war in violation of international law.

Even so, none of these instruments prevented the horrors of World War II. At the war's end, the allies established tribunals at Nuremberg and Tokyo to try defeated leaders, soldiers, and sailors accused of war crimes, mainly crimes against peace, which included the planning, initiating, and waging of wars of aggression in violation of international law; crimes against humanity, including exterminations, deportations, and genocide; war crimes on the battlefield; and conspiring to commit the criminal acts of the first three counts. Of twenty-four major German defendants, three were acquitted, four imprisoned from ten to twenty years, three imprisoned for life, and twelve sentenced to hang. (Two were not tried, one owing to suicide and one to physical incapacity.) Of twenty-five major defendants in Japan, two received prison terms, sixteen life imprisonment, and seven were sentenced to hang. Both tribunals adopted the "Nuremberg principle," which held the individual and not just the state liable for violations of the laws of war. This principle was soon a maxim of military training in most developed nations.

With the adoption of the United Nations Charter in 1945, almost all the nations of the world committed to the peaceful settlement of disputes and agreed to renounce war except in self-defense. Under the sponsorship of the United Nations, additional conventions have been adopted outlawing genocide and crimes against humanity; further limiting the use of weapons of mass destruction, such as nuclear and biological weapons, and of particular inhumanity, such as exploding bullets; and further refining standards for the treatment of prisoners and the wounded. The Geneva Conventions of 1949 refined duties to the wounded and sick on land, to the wounded, sick, and shipwrecked at sea, to prisoners of war, and to civilians. Conventions in 1954 and 1977 sought to protect property of great cultural significance and to end deliberate acts of war that harm the environment.

The Cold War and After

The Cold War between the U.S. and the Soviet Union, the Korean War, and the American war in Vietnam raised new questions about the nature and application of the laws of war. The laws of war traditionally applied only to conflicts between de jure states, and controversies arose over the legality of U.S. actions when war was not declared, as with U.S. involvement in Vietnam and Cambodia in the 1960s. The Vietnam War also led to debates over the legal definition of war as a civil war, guerrilla war, or national war; the applicability of the laws of war in the absence of a uniformed enemy; the adherence of the parties to the laws and conventions of war; and the tactics used by the belligerents, particularly the American use of carpet bombing and defoliants, which damaged noncombatant areas.

Blame in these disputes was not one-sided. The North Vietnamese and Vietcong used terrorism and refused to adhere to the 1949 Geneva Convention—they did not, for example, permit the International Red Cross to inspect prisoner-of-war camps.

Greater agreement on matters of international law and the law of war followed the end of the Cold War in the 1990s. With American support, the U.N. Security Council created the International Criminal Tribunal for the Former Yugoslavia in 1993 and the International Criminal Tribunal for Rwanda in 1994. Both tribunals applied the Nuremberg principle and actively investigated and convicted individuals, including former Yugoslav president Slobodan Milosevic, for violations of the Geneva Convention of 1949. They were charged to investigate and prosecute genocide, violations of the laws and customs of war, and crimes against humanity. The violation of the laws and customs of war included using poisonous weapons or other weapons calculated to cause unnecessary suffering; wanton destruction of civilian areas not justified by military necessity; attack or bombardment of undefended towns; seizing or harming buildings dedicated to religion, charity, or education, or to the arts and sciences, or historic monuments and works of art and science; and plundering public or private property.

At Rome in 1998 a U.N. conference opened for signature a treaty establishing an International Criminal Court, with global jurisdiction to try individuals whose governments are unwilling to try them when they have been accused of any of various "crimes against humanity"—the definitions of which are similar to those established by the Yugoslavia and Rwanda tribunals. To become effective the treaty needed the ratification of sixty states, a goal that was achieved in April 2002. The United States had signed in 2000, but withdrew its signature in 2002.

On 11 September 2001 an attack by a terrorist organization undirected by any state, but apparently sheltered by a theocratic de facto government in Afghanistan, destroyed the towers of the World Trade Center in New York, one of the largest office buildings in history and a center of the commercial world. The attack killed nearly three thousand people, mainly Americans but including people from many nations. The response of the United States and its allies was to demand surrender of the leaders of the attack, and, in the absence of satisfaction, to attack the armies of the Afghan government while seeking to arrest the terrorists. As much criminal enforcement as military action, this response further signaled a comprehensive change in the structure of the laws of war, which now include an element of the enforcement of international criminal law.


Best, Geoffrey. War and Law Since 1945. Oxford and New York: Clarendon, 1994.

Brownlie, Ian. International Law and the Use of Force by States. Oxford: Clarendon, 1963.

Holland, Thomas Erskine. The Laws of War on Land (Written and Unwritten). Oxford: Clarendon, 1908.

Jennings, R. Y., and A. Watts. Oppenheim's International Law. 9th ed. London: Longmans, 1992

Roberts, Adam, and Richard Guelff. Documents on the Laws of War. Oxford: Clarendon, 1989.

Taylor, Telford. The Anatomy of the Nuremberg Trials: A Personal Memoir. New York: Knopf, 1992.

United States. War Department. General Staff. Rules of Land Warfare. Washington, D.C.: Government Printing Office, 1914. U.S. Army field manual.


See alsoGeneva Conventions ; Hague Peace Conferences ; Kellogg-Briand Pact ; Versailles, Treaty of .

Laws of War

views updated May 18 2018

Laws of War. The idea of laws of war is ancient and ubiquitous; fragmentary indications appear in the records of most known civilizations and cultures. The inter national laws of war as known today, however, are of relatively modern and regional origin. The Roman concept of a law of nations (jus gentium), persisting through Europe's medieval centuries and ingesting elements of Christian “just war” doctrine, chivalric honor, military professionalism, and commercial prudence, produced by the sixteenth century a body of customary principles and rules purporting to show how to judge whether a war was justified (jus ad bellum) and how wars should ideally be conducted (jus in bello). Reality, always falling short of the ideal, became so horrific in the Thirty Years' War that the Dutch Christian‐humanist‐ diplomat Hugo Grotius (1583–1645) was prompted to publish in 1625 De jure belli ac pacis (Concerning the Law of War and Peace), usually considered the first definitive text on international law. Accepting war as a legitimate political institution, he maintained the just war thesis that it should not be begun without good cause, and argued with moral fervor that war could, indeed should, be conducted with more moderation than was usually the case. When, in the later nineteenth century, modern international law crystallized and the customary laws of war began to be codified, Grotius's visions of international community and universal standards renewed the respect for him that persists today.

The temporary eclipse of jus ad bellum did not mean that jus in bello was neglected. Men of honor took it seriously. Self‐respecting commanders of opposing forces made local agreements (“conventions”) to facilitate exchanges of prisoners and protect medical units. Recurrent disputes about particular incidents testified to the persistence of the ideas that there must be standards for governing the conduct of military operations, and that civilized states should wish their armed forces to observe them. So demanding had these ideas become by mid‐nineteenth century that they issued in four epochmaking and trail‐blazing events: the Paris Declaration of 1856, regulating the relations of belligerents and neutrals in maritime war; the Geneva Conventions of 1864; General Order No. 100 of the U. S. Army of 1864, Instructions for the Government of [Its] Armies in the Field—often known, after its principal author, as “the Lieber code”; and the St. Petersburg Declaration of 1868, a prohibition of an “atrocious” new weapon (explosive bullets).

From those close‐bunched beginnings, the laws of war developed along two main lines. “Geneva law” aimed to protect victims and innocents: the 1929 revision added to the existing conventions (for sick and wounded combatants on land and sea), a third regarding prisoners of war; in 1949, a fourth aimed to protect civilians who fell into enemy hands at the outbreak of hostilities or because of military occupation. The other line, law regarding the conduct of hostilities, of which Francis Lieber's code was for long the most famous and complete national example, became known as “Hague law” after the international standard setting in 1899 (reaffirmed by the Fourth Hague Convention of 1907) of the Hague Regulations Respecting the Laws and Customs of War on Land. Supplemented since 1977 by the First Protocol Additional to the Geneva Conventions (in fact, a convergence of Geneva and Hague law, to which most states by now have acceded), the Hague Regulations have ever been, and still are, fundamental to the laws of land war. Along with the Geneva Conventions, they formed the basis for the war crimes trials after World War II; most of which had to do with the behavior of armed forces in (contested) occupation of alien territories, and with the treatment of prisoners.

Standards for the conduct of war by air and sea have not been so easily reached. In these fields especially, military applications of science and technology have posed problems defying simple solution. New inventions promising military advantage have often at first been denounced as dishonorable or inhumane, but a few have ultimately been added to the list of weapons (e.g., chemical and biological weapons) covered by multilateral treaty prohibitions (1925 and 1972, respectively). It remains to be seen how effective will be the 1981 prohibitions or restrictions on the use of certain conventional weapons (mainly land mines, boobytraps, and incendiary weapons). Efforts were made between 1919 and 1939 to restrict submarine and aerial warfare, but they proved useless during World War II. Submarines were so vulnerable on the surface that, having to stay submerged, they could not observe the classic distinction between civilian and military; together with mines, they revolutionized war at sea by making possible blockades more total than ever before. Bombers dared not fly so low or slow that they could guarantee to hit only military objectives; at the same time, the passions of prolonged total war tended to encourage the indiscriminate and terroristic bombing of civilians. Both sides having waged air and sea war in these extreme and disproportionate ways, they figured hardly at all in the Nuremberg and Tokyo International Military Tribunals and the many nationally run war crimes trials. Not until 1977 were these specific problems addressed. Among the more valuable achievements of the First Additional Protocol is civilian‐protecting definition of military objectives, and, associated with it, rules of proportionality aimed at reducing to the realistic minimum the incidental risks to nonmilitary persons and places.

The laws of war are incapable of perfect observance. Beyond the fact that law like all other elements of war is subject to the erosions of confusion, error, and chance, observance is likely to be highest when states wish a war to remain limited, when neutrals are critically watchful, and when well‐disciplined armed forces fight one another in a relatively civilian‐free environment. The “desert war” in North Africa (1940–43), and the brief Falklands War in the South Atlantic between Britain and Argentina (1982) are exceptional. Circumstances are rarely so favorable. Wars between states are more likely to be all‐out than limited; nor are they often simply between states. The laws of war make some room for “noninternational armed conflict,” but nonstate parties may not wish or be able to conduct hostilities in a style consistent with the law, while states combating them may not like to regard them as if they were lawful belligerents. Civilians tend to be difficult to distinguish from combatants in guerrilla warfare, or revolutionary and people's wars; in such situations, all parties are tempted to turn to terror. And through it all runs the problem that has forever dogged the laws of war, and whose handling reveals the quality of the culture and the politics of which the warrior is the armed representative: how to distinguish what may be militarily necessary from what is merely convenient, and how to judge when enough violence is enough. Important to all, the laws of war are not a matter of concern solely to the military.
[See also Geneva Protocol on Chemical Warfare; Hague Peace Conferences: Just War Theory; War: Nature of War; War Crimes.]


Oppenheim's International Law, Vol. 2: Disputes, War and Neutrality, 1905; 7th ed., ed. Hersch Lauterpacht, 1952.
Daniel O'Connell , The Influence of Law on Sea Power, 1975.
David Forsythe , Humanitarian Politics: The International Committee of the Red Cross, 1977.
Philip R. Piccigallo , The Japanese on Trial. Allied War Crimes Operations in the East, 1945–1951, 1979.
Adam Roberts and Richard Guelff, eds., Documents on the Laws of War, 1982; 2nd ed. 1989.
W. Hays Parks , Air Law and the Law of War, Air Force Law Review, vol. 32, no. 1 (1990), pp. 1–225.
Telford Taylor , The Anatomy of the Nuremberg Trials, 1993.
Geoffrey Best , War and Law Since 1945, 1994.
Michael Howard, George J. Andreopoulos, and Mark R. Shulman, eds., The Laws of War: Constraints on Warfare in the Western World, 1994.

Geoffrey Best

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