Grove Press
Grove Press
Grove Press

War Law

Understanding International Law and Armed Conflict

by Michael Byers

“Should be read, and pondered, by those who are seriously concerned with the legacy we will leave to future generations.” —Noam Chomsky

  • Imprint Grove Paperback
  • Page Count 224
  • Publication Date March 27, 2007
  • ISBN-13 978-0-8021-4294-8
  • Dimensions 5.5" x 8.25"
  • US List Price $17.00

About The Book

International law governing the use of military force has been the subject of intense public debate. Under what conditions is it appropriate, or necessary, for a country to use force when diplomacy has failed? Michael Byers, a widely known world expert on international law, weighs these issues in War Law.

Byers examines the history of armed conflict and international law through a series of case studies of past conflicts, ranging from the 1837 Caroline Incident to the abuse of detainees by U.S. forces at Abu Ghraib prison in Iraq. Byers explores the legal controversies that surrounded the 1999 and 2001 interventions in Kosovo and Afghanistan and the 2003 war in Iraq; the development of international humanitarian law from the 1859 Battle of Solferino to the present; and the role of war crimes tribunals and the International Criminal Court. He also considers the unique influence of the United States in the evolution of this extremely controversial area of international law.

War Law is neither a textbook nor a treatise, but a fascinating account of a highly controversial topic that is necessary reading for fans of military history and general readers alike.


“If Britain suspected that a Boston bar harbored IRA terrorists, would it be justified in lobbing cruise missiles into the city? Byers . . . achieves plenty of similar provocations in this lucid primer.” —Kirkus Reviews

“Lucid, brisk.” —Greg Moran, Copley News Service

“Succinct, highly readable, and important.” —Booklist

“This short book serves as a primer for students and teachers alike . . . Byers is clearly knowledgeable. . . . Certainly a relevant, timely and informative work.” —Daniel Levinson, Kliatt

“He succeeds remarkably well. So well indeed, that the book can be read with interest and profit by lawyers as well as lay people. . . . Stimulating and scholarly, wholly unstuffy and extremely readable.” —Professor Malcolm Forster, Legal Week

“Should be read, and pondered, by those who are seriously concerned with the legacy we will leave to future generations.” —Noam Chomsky

“Byers, an unabashed believer in the project of international law, is alert to the political context in which it inevitably has to be interpreted and applied.” —Phillipe Sands, London Review of Books

“Professor Byers’s book goes to the heart of some of the most bitterly contested recent controversies about the International Rule of Law. As we debate how to legitimize interventions in the affairs of sovereign states in order to deal with threats and to prevent the abuse of human rights, we should take serious note of the issues raised by Professor Byers.” —Chris Patten, Chancellor of Oxford University


Part One: United Nations Action
1 — Security Council Authorization

In 1945, representatives from fifty countries gathered in San Francisco to create a new international organization: the United Nations. The negotiations took place in the aftermath of the Second World War with its tens of millions of casualties, including the millions of civilians slaughtered during the Holocaust and the hundreds of thousands who were to die as a result of the atomic bombings of Hiroshima and Nagasaki. The diplomats sought an institution and set of rules that would, in their words, “save succeeding generations from the scourge of war.” The treaty they negotiated—the Charter of the United Nations—focused on preserving the peace and empowering multilateral responses to threats or breaches of the peace. One hundred and ninety-two countries have since ratified the UN Charter and are thereby “member states” of the United Nations with all the rights and obligations that entails.

Again, the central obligation of membership is set out in Article 2(4) of the UN Charter:

All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.

Interpreted according to the 1969 Vienna Convention on the Law of Treaties, the ordinary meaning of Article 2(4) is clear: the use of force across borders is categorically prohibited. This interpretation is supported by the Charter’s context, object and purpose. The preamble to the UN Charter states that it is designed to “ensure by the acceptance of principles and the institution of methods, that armed force shall not be used, save in the common interest.” The Charter sets out only two exceptions to the prohibition on the use of force. The first exception empowers the UN Security Council, a specialized decision-making body made up of representatives from fifteen member states of the United Nations, to authorize the use of force “to maintain or restore international peace and security.”

Of the fifteen countries on the Security Council, five—Britain, China, France, the United States and the Soviet Union (now Russia)—are designated as “permanent members.” Each permanent member has the power to veto any proposed resolution. Sometimes the mere threat of a veto is enough to prevent a resolution from being put to a vote. In the absence of a veto, nine votes are required for a resolution to pass. This requirement means that the support of at least four non-permanent members is needed for any resolution to be adopted, and more than four in the event that one or more permanent members choose to abstain from voting. In early 2003, British government’s decision not to put its so-called “second resolution” on Iraq to a vote was conditioned as much by opposition from non-permanent members as it was by the threat of a French or Russian veto.

Under Chapter VII of the UN Charter, the Security Council has a broad authority to “determine the existence of any threat to the peace, breach of the peace, or act of aggression.” The Council has an equally broad authority to decide which measures shall be taken to “maintain or restore international peace and security.” Such measures can include imposing economic sanctions and, even more significantly, authorizing the use of military force against disobedient countries.

During the Cold War, the UN Security Council’s power to authorize the use of force went largely unexercised, apart from an ambiguous, possible authorization in Korea and a clear but very constrained authorization to the United Kingdom with regard to Southern Rhodesia.


North Korea’s invasion of South Korea in 1950 prompted the newly created Security Council to “recommend” that UN member states “furnish such assistance to South Korea as may be necessary to repel the armed attack and to restore international peace and security in the area.” The resolution was highly controversial. First, the Soviet Union boycotted the Council meeting at which the resolution was passed. According to an ordinary meaning interpretation of Article 27(3) of the UN Charter, which stipulates that substantive resolutions must receive the “concurring votes” of all the permanent members, the Soviet Union’s absence should have prevented adoption of the resolution. Nevertheless, most governments treated the resolution as valid. Second, since the resolution was recommending—rather than expressly authorizing—the use of force, it was questionable whether the Security Council was actually using its Chapter VII powers.

The Korean War had an important consequence for the international law on the use of force. Today, it is widely accepted that absences or abstentions by one or more permanent members of the Security Council are not fatal to resolutions under vote. If a permanent member wishes to block a resolution, it must actually cast a negative vote. Permanent members are now careful to attend all Security Council meetings lest their absence facilitate the law-making efforts of states whose policies they oppose.

In 1964, Ian Smith, the leader of the Rhodesian Front, became prime minister of the British colony of Southern Rhodesia. After failing to persuade London to set the colony free, Smith and his government made a “unilateral declaration of independence”—under white minority rule—on 11 November 1965.

The UN General Assembly, a body made up of all UN member states, had adopted its first resolution on Rhodesia in 1961. The resolution deplored “the denial of equal political rights and liberties to the vast majority of the people of Southern Rhodesia.” However, the General Assembly can only recommend—and not authorize—economic sanctions or military action. Accordingly, the Assembly responded to the 1965 Rhodesian declaration of independence by condemning it as a “rebellion” by “unlawful authorities” and a “racialist minority” and recommending that the Security Council consider the situation “as a matter of urgency.”

The Security Council condemned “the usurpation of power by a racist settler minority,” stating that the declaration of independence had “no legal validity.” The Council also called upon countries to break all economic ties with Rhodesia, but neither imposed legally binding sanctions nor authorized the use of force.

Five months later, the Security Council learned that substantial quantities of oil were about to reach landlocked Rhodesia from tankers offloading oil into a pipeline that ran from the Mozambique port of Beira. The Council responded with Resolution 221, which deemed the situation a “threat to the peace.” Most importantly, the resolution called upon the United Kingdom “to prevent, by the use of force if necessary, the arrival of vessels reasonably believed to be carrying oil destined for Southern Rhodesia.”

Although the language of Resolution 221 did not expressly refer to the Security Council’s powers under Chapter VII, the resolution was probably the first occasion on which that part of the UN Charter was used. That the resolution was adopted at all is remarkable, given the intense Cold War rivalry between the two veto-holding superpowers. The specific nature of the Rhodesian situation—a white racist minority rebellion in a part of the world where the Soviet Union and United States were competing for influence over newly independent black governments—helps explain its adoption, as do the narrowly defined limits of the apparent authorization given to the UK.

Eight months later, in December 1966, the Security Council imposed the first mandatory economic sanctions in UN history. In Resolution 232, the Council again determined that the situation in Rhodesia constituted a threat to international peace and security. Using the words “all State Members of the United Nations shall prevent” to avoid any ambiguity, the resolution prohibited the import of any of Rhodesia’s principal products, as well as the export of arms, oil or oil products to the country. The mandatory embargo was later broadened to sever air links, ban the acceptance of Rhodesian passports, withdraw all consular and trade representatives from the country and break off diplomatic relations and ground transportation links.

It took almost a decade, but these external pressures eventually led to all-party talks at Lancaster House in London in 1979. The talks produced a peace agreement and a new constitution for the country that guaranteed minority rights. In 1980, Robert Mugabe and his Zanu Party won British-supervised elections. Mugabe was named prime minister and, on 18 April 1980, the colony of Southern Rhodesia became the independent country of Zimbabwe. Although the Security Council’s authorization of the use of force played only a minimal role in the international effort that ultimately led to a sovereign Zimbabwe, Resolution 221 is a milestone in the ongoing development of international rules on the use of force, and of Chapter VII of the UN Charter in particular.

The Security Council’s period of general inactivity, coinciding with the Cold War, ceased after the Iraqi army invaded and seized the small neighbouring country of Kuwait on 2 August 1990. The invasion was a blatant violation of the UN Charter and its prohibition in Article 2(4) on the use of force against the “territorial integrity and political independence” of any UN member state. The Security Council responded the very next day, adopting Resolution 660. Acting expressly under Chapter VII, the Council condemned the invasion and demanded Iraq’s immediate withdrawal from Kuwait. A few days later, the Council imposed stringent mandatory economic sanctions on Iraq.

Four months of intense diplomatic activity followed as world leaders sought to persuade Iraqi president Saddam Hussein to comply with international law and the orders of the Security Council. When Saddam refused, the Security Council increased its pressure. On 29 November 1990, the Council adopted Resolution 678 in which it “decided to allow Iraq one final opportunity” to remove its forces from Kuwait, and set a deadline of 15 January 1991. This was not an empty gesture. Resolution 678, which like Resolution 660 was expressly adopted under Chapter VII, went on to authorize countries co-operating with the government of Kuwait to “use all necessary means” to remove the Iraqi forces and “restore international peace and security in the area”—in the event that Iraq failed to withdraw its troops. The phrase “use all necessary means” was clearly intended to authorize the use of military force.

By the time the deadline arrived, the US-led coalition had deployed nearly 700,000 troops to the region; they subsequently needed little time to remove Saddam’s forces from Kuwait. Operation Desert Storm was a resounding success, not only militarily, but also for the authority of the Security Council and the broader UN. President George H. W. Bush spoke proudly of the “new world order” that was reflected in this exercise in global multilateralism. Unfortunately, Bush’s new order was remarkably fragile, as events in the Balkans soon demonstrated.

War consumed Bosnia-Herzegovina from April 1992 to November 1995, following the collapse of the Federal Republic of Yugoslavia and the eruption of ethnic tensions that since the Second World War had been largely suppressed by totalitarian rule. A defining feature of the conflict was the prevalence of ethnically motivated killings, rapes and expulsions, primarily involving Muslim victims. During the first five months of the conflict, more than 700,000 people were driven from an area covering 70 per cent of Bosnia-Herzegovina. The atrocities committed fell within the scope of the 1948 Convention on the Prevention and Punishment of the Crime of Genocide (the Genocide Convention), Article 2 of which states:

In the present Convention, genocide means any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such:

(a) Killing members of the group;
(b) Causing serious bodily or mental harm to members of the group;
(c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;
(d) Imposing measures intended to prevent births within the group;
(e) Forcibly transferring children of the group to another group.

During the Bosnian War, most journalists and state officials too readily adopted the Serbian euphemism “ethnic cleansing” to describe the horrors that were taking place. The use of this label enabled Western governments to avoid the groundswell of public opinion that would likely have arisen had they invoked the more accurate, morally resonant word “genocide.” It may even have been an attempt by those same governments to shirk their responsibility “to prevent and to punish” genocide under Article 1 of the Genocide Convention. However, evasive terminology did not prevent public evocations of the Holocaust in describing the situation in Bosnia. Some 250,000 people were killed, thousands more were tortured and starved in concentration camps, millions lost their homes and countless women were raped and forcibly impregnated—and all this in a rapidly unifying, post-Cold War Europe that had as one of its central missions the promotion of human rights.

Shortly after the war began, the UN Security Council passed Resolution 713. Adopted expressly under Chapter VII of the UN Charter, the resolution imposed an arms embargo on all of the former Yugoslavia. The embargo arguably did more harm than good because it preserved a military imbalance between the Serbian forces, who had acquired most of the heavy weapons of the previous Yugoslav army, and the less well-armed Bosnian Muslims. The United States later sought to rescind the resolution and lift the embargo, but was unable to do so because of opposition by Russia, which was concerned about US influence in the region and identified religiously with the Eastern Orthodox Serbs. The arms embargo against the former Yugoslavia remained in force until the Dayton Accords brought an end to the conflict in November 1995, though weapons were smuggled into the country, some with the assistance of the United States.

In 1992, the UN Security Council, acting under Chapter VII, established the United Nations Protection Force (UNPROFOR) to provide peacekeeping—the non-violent monitoring of ceasefires, including by providing a neutral presence in buffer zones—in the former Yugoslavia. In 1993, the Security Council extended the force’s mandate to include the creation and protection of “safe havens” in Bosnia. The same year, again acting under Chapter VII, the Council took the novel step of creating an international tribunal to prosecute individuals who had allegedly committed atrocities and to deter further violations of international law. The International Criminal Tribunal for the former Yugoslavia (ICTY), located in The Hague, is a subsidiary organ of the UN Security Council. The ICTY has jurisdiction to investigate and prosecute war crimes and crimes against humanity committed in the former Yugoslavia since 1991. This jurisdiction continued through the 1999 Kosovo War and remains in place today. Moreover, since the ICTY was created by a Chapter VII resolution and not by a treaty, the tribunal’s jurisdiction took effect immediately—without the need for the consent of individual countries. Slobodan Milošević, the former President of Yugoslavia, was thus unable to avoid the tribunal, and has been on trial in The Hague since 2001. In 1994, the UN Security Council followed the model of the ICTY in creating the International Criminal Tribunal for Rwanda, though the jurisdiction of this tribunal is limited to events occurring during 1994, the year the genocide took place. Both tribunals served as influential models for the International Criminal Court, a permanent institution with much broader jurisdiction, the treaty for which was adopted in 1998 and entered into force in 2002. They have also obtained a number of convictions, generated valuable precedents on questions of international criminal law, and generally helped advance international justice elsewhere.

In 1993, NATO, embarrassed by massacres in the UN ‘safe havens’ in the former Yugoslavia, and Europe’s failure to stop them, bombed Serbian weapons and supply lines in Bosnia. The bombing was conducted under a complex mandate, provided through UN Security Council Resolution 836 of 4 June 1993, which required close cooperation on targeting decisions between NATO and then UN Secretary General Boutros Boutros-Ghali. The agreement proved unwieldy and ineffective. In July 1995, more than 7,000 Muslim men and boys were slaughtered in the “safe haven” of Srebrenica as 400 Dutch peacekeepers stood by, their pleas for NATO air support unanswered. In 2001, the ICTY confirmed that the massacre was an act of genocide when it convicted Radislav Krstic, the Yugoslav general in charge, and sentenced him to forty-six years in prison.

International efforts to restore peace to the former Yugoslavia were, on the whole, embarrassingly ineffective, not due to any lack of international law but because of a near absence of international political will. The lack of political will continues today: in December 2004, Carla del Ponte, the ICTY prosecutor, publicly chided NATO governments for having done little over the course of a decade to bring two of the principal alleged perpetrators of the atrocities in Bosnia-Herzegovina, Radovan Karadzic and Ratko Mladic, to justice. That the two indicted men remain at liberty in the eastern mountains of Bosnia is chilling evidence of the transitory and opportunistic character of most international efforts to prevent or punish international crimes.

That said, the four situations discussed in this chapter—Korea (1950), Southern Rhodesia (1966), Iraq (1990-91) and Bosnia-Herzegovina (1992-5)—saw the UN Security Council exercise its Chapter VII powers to authorize force in new and quite different ways. With the exception of Iraq, however, the consistent theme of this period was one of hesitation, as the politics of the Council, an inherently political body, prevented it from acting decisively and expansively to maintain and restore the peace. This disappointing picture began to change in the 1990s, as the next chapter explains.