A. Concept and Definition
1 The term and concept of ‘war crimes’ is not used uniformly. A wider approach defines war crimes as all acts constituting a violation of the laws or customs of war, irrespective of whether the conduct is criminal (Werle and Jessberger  391; US Army Military Manual, § 499, FM 27–10; JS Pictet, ed, Geneva Convention I  351). The present contribution is based on a definition of war crimes in stricto sensu: A war crime is any act, or omission, committed in an armed conflict that constitutes a serious violation of the laws and customs of international humanitarian law and has been criminalized by international treaty or customary law (Humanitarian Law, International). This definition requires at least two conditions qualifying a conduct to a war crime. First, a violation of international humanitarian law, and second, the criminalization of the conduct under treaty or customary international law (Cassese  67). The applicability of the rules of international humanitarian law implies that a war crime must be satisfactorily connected to an armed conflict (Armed Conflict international; Armed Conflict, Non-International; Belligerency). The second condition requires that customary or international treaty law must provide legal norms entailing individual criminal responsibility for the perpetration of such a violation.
2 In contrast to crimes against humanity and genocide, crimes which are established as independent crimes under international law, the concept of war crimes is based on the accessoriness between the primary rules concerning prohibited acts under international humanitarian law and secondary rules concerning the punishment of war crimes. This structure underlies the dynamic character of the concept of war crimes, as it can be subject to change (Bothe in Cassese/Gaeta/Jones  381). While, within the classical understanding of international law, violation of its rules by State officials or individuals only engage collective State responsibility, the concept of war crimes goes beyond that principle and imposes liabilities upon individuals as well. War crimes can be prosecuted directly by International Criminal Tribunals or indirectly by national courts. The decision depends on whether the jurisdiction of the international court is primary or complementary to national courts (see International Criminal Law). As will be shown, war crimes are not only restricted to international armed conflicts, they can also be committed during non-international armed conflicts.
B. Historical Evolution of Legal Rules
1. Early Developments
3 The origins of war crimes can be found in the traditional laws of war, today called international humanitarian law; these laws regulate the conduct of armed conflicts whose rules were derived from international conventions and customary international law. The evolution of war crimes is part of the progressive development and codification of international humanitarian law by promoting individual criminal responsibility for serious violations committed under its norms. The idea of individual criminal responsibility—that individuals under international law should be responsible for serious violations of the laws of war and not only the belligerent State—is not an invention of the 20th century; it has developed in stages and goes back to the practice of trial and punishment for those guilty of such violations in the medieval period (La Haye 104). One of the earliest examples of an international prosecution in Medieval Europe is the 1474 trial of Peter von Hagenbach in Breisach, Germany, which convicted von Hagenbach of murder, rape, perjury, and other crimes against the ‘laws of God and man’ (Schwarzenberger 465). Von Hagenbach led a regime of brutality and terror and committed numerous violent acts against the inhabitants of Breisach and neighboring territories. A large coalition (France, Bern, Austria and the towns and knights of the Upper Rhine) put these atrocities to an end and installed an ad hoc tribunal consisting of 28 judges from the allies. Even though the Hagenbach trial differed extensively from contemporary developments of International Criminal Tribunals, it is often cited as the ‘first reported international war crime trial’ (Bassiouni  197).
4 At the request of the United States President Abraham Lincoln, Francis Lieber, a Columbia University professor of law, prepared the Lieber Code of 1863 (‘Instructions for the Government of Armies of the United States in the Field’), a text which represents the first attempt to codify the laws of war. These instructions, applicable to the Union army during the American Civil War, established the principle of individual criminal responsibility for comprehensive violations listed in the text, such as pillage, rape, or abuse of prisoners (see Art. 44 Instructions for the Government of Armies of the United States in the Field). Codified as a municipal law instrument, the prosecution of war criminals was limited to American Soldiers and only binding to them. Prior to the 19th century, the regulation of the laws of war was a matter of national legislation (Meron 1). Nonetheless, the codification had an enormous influence on the future evolution of the laws of war and the principle of criminalizing violations of the laws and customs of war.
5 As a result of the Hague Peace Conferences (Hague Peace Conferences [1899 and 1907]), the Hague Conventions of 1899 and 1907 were the first multilateral agreements regulating the conduct of war. However, they neither clarified nor limited the principle of individual criminal responsibility and focused only on the rights and obligations of States as the classical subjects of international law.
6 In 1919, the judicial prosecution of individuals who had committed war crimes during World War I was reflected by the Commission on the Responsibility of the Authors of the War and on Enforcement of Penalties that analysed the applicable legal norms and listed 32 offences involving serious violations of the laws and customs of war (Commission on the Responsibility of the Authors of the War and on Enforcement of Penalties  14 AJIL 95).
7 The Versailles Peace Treaty (1919) (Treaty of Peace between the Allied and Associated Powers and Germany [signed 28 June 1919, entered into force 10 January 1920] 225 CTS 188) was the first international convention to provide specific regulation of individual criminal responsibility for violations of international humanitarian law. Art. 227 Versailles Peace Treaty included the indictment and trial of the former Emperor of Germany and Art. 228 (1) recognized ‘the right of the Allied and Associated Powers to bring before military tribunals persons accused of having committed acts in violation of the laws and customs of war.’ To fulfill this provision the Versailles Peace Treaty obliged the government of the German Reich to hand over the accused persons (Art. 228 (2)) and to support the prosecution of the Allies (Art. 230). However, no international tribunal was established. Instead, the allied powers relinquished their right to prosecute war criminals and accepted the compromise offered by the German government to hold the trials before the German Reich Supreme Court in Leipzig (Bassiouni  34; Mc Cormack  49). In the end, only 13 proceedings against alleged war criminals reached the trial stage, nine trials came to a judgment of which none was fully executed (Werle and Jessberger  4). This disastrous beginning of the prosecution of war crimes was completed by the fact that the German Emperor was granted asylum in the Netherlands and was never held individually accountable for his acts.
8 The crucial historical moment for the prosecution of war crimes was probably the recognition of individual criminal responsibility in a statement by the International Military Tribunal of Nuremberg (‘IMT’) that pointed out in 1946: ‘[E]nough has been said to show that individuals can be punished for violations of International Law. Crimes against international law are committed by men, not by abstract entities, and only by punishing individuals who commit such crimes can the provisions of international law be enforced’ (Judgment of the International Military Tribunal for the Trial of German Major War Criminals [Nuremberg 30th September and 1st October 1946] 65). It was also the Charter of the IMT that defined war crimes in Art. 6 (b) as ‘violations of the laws or customs of war.’ In consideration of this provision, the IMT held that violations of the Hague Regulations of 1907 and the Geneva Conventions of 1929 ‘were already recognized as war crimes under international law’ (Judgment 253). On the important question of how the Hague and Geneva Regulations had generated customary international law, the tribunal did ‘not [find] necessary to decide’ and simply stated that ‘by 1939 these rules laid down in the convention were recognized by all civilized nations, and were regarded as being declaratory of the laws and customs of war which are referred to in Article 6 (b) of the Charter’ (Judgment 254). Even though this finding was not entirely justified, it is beyond controversy that the testimony of the IMT constituted a crucial stepping stone in the recognition of individual criminal responsibility for war crimes committed under international law. In contrast to the aftermath of World War I, the IMT and the International Military Tribunal for the Far East in Tokyo (‘IMTFE’) prosecuted officials for their perpetration of war crimes during World War II (International Military Tribunals). Despite that, the problem of victor’s justice remained unresolved given that the practice of selective prosecution of the vanquished was continued by these tribunals.
2. The Grave Breaches Regime of the Geneva Conventions
9 After World War II, to ensure the respect of the laws of war, the Geneva Conventions I-IV (1949) for the protection of war victims listed certain serious violations of the Conventions as ‘grave breaches’, providing individual criminal responsibility to persons committing such breaches (see Arts 49–51 Geneva Convention I, Arts 50–52 Geneva Convention II, Arts 129–31 Geneva Convention III, Arts 146–48 Geneva Convention IV). As a consequence, under the Geneva Conventions the signatory States are compelled to provide penal sanction for such acts under domestic law and to try perpetrators of grave breaches or to extradite them to another State at its request (aut dedere aut iudicare) (JS Pictet, Commentary vol 4  591). In each of the Conventions, grave breaches are defined by an exhaustive list of acts applicable in international armed conflicts. Art. 85 (5) Additional Protocol I codified that the grave breaches of the Geneva Conventions and of the Protocol ‘should be regarded as war crimes’ (Geneva Conventions Additional Protocol I). Due to the universal recognition of the Geneva Conventions by all States (195 of 195), they are generally considered to reflect customary international law (O’Connell in Fleck  27, margin 126). However, Additional Protocol I, which extends the definition of grave breaches, has not enjoyed the same universal acceptance as the four Geneva Conventions (173 of 195, Sep 2014). The regime of grave breaches of the Geneva Conventions restricts the scope of individual criminal responsibility by the distinction of acts constituting an ordinary violation of the laws of war and those constituting serious violations (grave breaches). Only the latter should amount to war crimes and entail individual criminal responsibility for the perpetrators of those acts. Hence, not any ordinary violation of the Geneva Conventions qualifies as a war crime (Dinstein in Dinstein and Tabory  4). The list of ‘grave breaches’ in the Geneva Conventions and its Additional Protocol I is primarily concerned with, and must be directed against, persons or property protected under the Conventions, such as prisoners of war, the sick or wounded, or civilians, and entails individual criminal responsibility not only for committing but also for ordering grave breaches to be committed.
10 The concept of grave breaches raises the question of the relationship between the two categories: war crimes and grave breaches. A general response has already been given by the wording of Art. 86 (5) Additional Protocol I, which states that grave breaches shall be regarded as war crimes. According to this, grave breaches are nothing more than a treaty-based type of war crime. The peculiarity indeed consists of their character as ‘secondary rule’ through which violations of certain primary rules of international humanitarian law entail individual criminal responsibility in International Law (Abi-Saab 114). By introducing the regime of grave breaches, the difficult duty of identifying customary or treaty rules establishing breaches of the ius in bello as war crimes has been simplified by the constitution into a proper category of particularly serious violations. That does not mean that that the range of war crimes under customary international law is confined to such ‘grave breaches’. On the other hand, not every ‘grave breach’ of Additional Protocol I is necessarily a war crime under customary international law (eg, apartheid).
3. The International Criminal Tribunals for the Former Yugoslavia and Rwanda
11 After the time of the Cold War, the first decisive development concerning the prosecution of individuals for violations of the laws of war was the establishment of the International Criminal Tribunal for the Former Yugoslavia (ICTY), as well as the International Criminal Tribunal for Rwanda (ICTR), both of which were created as ad hoc tribunals by the United Nations Security Council and find their legal basis in Chapter VII and Art. 25 UN Charter.
12 The Statute of the ICTY, which is restricted to the former Yugoslavia (Yugoslavia, Dissolution of), did not use the term ‘war crimes’ but included two categories of them: Art. 2 ICTY Statute penalizes ‘grave breaches of the Geneva Conventions against persons or property protected under the provisions of the relevant Geneva Convention’ committed in an international armed conflict; Art. 3 ICTY Statute penalizes ‘violations of the laws or customs of war’, amended by an illustrative list that contains elements of the Hague Rules of Land and Warfare as well as certain provisions of Additional Protocol I of the Geneva Conventions. Art. 3 ICTY Statute, as interpreted by the Tribunal, serves as a ‘general provision covering all violations of humanitarian law’ not qualified as grave breaches, acts of genocide, or crimes against humanity regardless of whether the violation occurs within the context of an international or non-international armed conflict (Prosecutor v Tadić [Decision on the Defence Motion for Interlocutory Appeal] [‘Interlocutory Appeal Decision’] ICTY-94–1-AR72 [2 October 1995] para. 89; Wolf 26). In the Tadić Case, the Appeals Chamber ultimately concluded that ‘all of these factors confirm that customary international law imposes criminal liability for serious violations of Common Article 3, as supplemented by other general principles and rules of the protection of victims of internal armed conflict, and for breaching certain fundamental principles and rules regarding means and methods of combat in civil strife’ (Interlocutory Appeal Decision paras 128–37, 134). This interpretation of the Appeals Chamber in the Tadić case signalled a breakthrough for the applicability of individual criminal responsibility for serious violations of humanitarian law in non-international armed conflicts.
13 The Statute of the ICTR covers, according to the nature of the conflict in Rwanda, war crimes committed in a non-international armed conflict. Art. 4 ICTR Statute therefore includes ‘violations of Article 3 common to the Geneva Conventions and of Additional Protocol II’ (Geneva Conventions Additional Protocol II ). In its first judgment in the Akayesu Case, the ICTR adopted the view of the Appeals Chamber in the Tadić Case and concluded that ‘the violation of these norms entail, as a matter of customary international law individual responsibility for the perpetrator.’ (Prosecutor v Akayesu [Judgment] ICTR-96–4-T [2 September 1998] para. 616). Even at this early stage, it is already evident that both courts considerably developed and substantiated the law of war crimes by their far-reaching jurisprudence.
14 The creation of the two ad hoc tribunals also strengthened the idea of a permanent international criminal court. Finally, the adoption of the ICC Statute in 1998 consolidated some of the crucial and still controversial conclusions achieved by the jurisprudence of the ICTY and the ICTR (International Criminal Court (ICC)). Particularly with regard to the contentious question of to what extent the jurisdiction of the ICC will encompass war crimes committed in non-international armed conflicts, the influence of the Tadić case cannot be overstated. This inter alia led to the adoption of a substantive list of war crimes committed in non-international armed conflicts into Art. 8 ICC Statute. Thus, the ICC Statute is, after the ICTR Statute, the second international instrument that explicitly recognized the criminal liability of individuals for war crimes committed in non-international armed conflicts. Some of the acts included in Art. 8 ICC Statute have been criminally sanctioned for the first time at the international level.
C. Serious Violations of International Humanitarian Law
16 Corresponding to the first two conditions, a war crime is based on a violation of a rule of international humanitarian law that is either customary in nature or based on treaty law (Henckaerts and Doswald-Beck  572). The necessary linkage clarifies that the law of war crimes as substantive law is not independent but accessorial to the primary rules of international humanitarian law (Werle and Jessberger  404). Consequently, war crimes must be interpreted in light of the rules of international law, and only if it is established that the act constitutes an infringement of an applicable norm of international humanitarian law can the act in question amount to a war crime.
Charles (Chip) Hauss
The concept and issue of war crimes are both relatively new. Of course, inhuman acts have been committed in wars throughout history. However, it was only with the Holocaust and other genocidal atrocities of World War II that politicians, lawyers, and average citizens alike began to think of some of the horrors of war as crimes for which perpetrators could be held legally accountable.
Before then, individual soldiers could be tried for individual crimes such as rape or murder. However, it was only when political and military leaders began to systematically target large civilian groups because of their nationality, ethnicity, gender, or religion that we began to see the necessity of holding political leaders accountable for their political decisions in a court of law.
What Are War Crimes?
It has long been considered acceptable for the victors to try the leaders of defeated countries for violations of international law after the completion of a war. However, it has only been in the last century and a half that rules and procedures for doing so have begun to be codified and regularized. The first major step came with the development of the Geneva Conventions for the treatment of prisoners of war, civilians, and others during combat. The Conventions were largely written by the International Committee of the Red Cross and have been ratified by many, though not all, states. They continue to be updated, most recently to include civil as well as international wars.
The other major turning point came at the Nuremberg and Tokyo trials of leading German and Japanese officials after World War II. The Nuremberg Trials were particularly important because they made steps toward defining what is meant by crimes against peace ("planning, preparation, initiation, or waging of a war of aggression, or a war in violation of international treaties") and against humanity ("murder, extermination, enslavement, deportation, and other inhumane acts committed against any civilian population before or during the war, or persecutions on political, racial, or religious grounds"). Those precedents were later approved by the General Assembly of United Nations and are now considered to be part of the main body of international law. After the systematic use of rape by Serbs in Bosnia and Croatia in the first half of the 1990s, it was added to the list of crimes.
There is, unfortunately, a considerable lack of clarity in these and other definitions, which have been offered for war crimes. First, there has been a very definite reluctance on the part of the international community to prosecute war crimes that either fall below a certain undefined magnitude or to even consider those that receive little or no coverage in the Western press. Second, as has been the case throughout history, it has proven all but impossible to hold victors accountable for alleged war crimes. Thus, there have been credible accusations against the United States for its bombing of Serbia during the Kosovo crisis in 1999 and for the impact of its sanctions on Iraq since the Gulf War of 1991. Similarly, many critics accuse Israel of violating international law in its continued occupation of the West Bank and the Gaza Strip and its more general treatment of Palestinians.
What's more, the prosecution of war crimes is highly controversial. Tens of millions of civilians lost their lives in fighting beginning with the Second World War, most of them on "religious, racial, or political grounds." Yet, there were only four war crimes tribunals convened between 1945 and the end of the century. The first two tried the leaders of Germany and Japan. The others were created to prosecute alleged perpetrators of genocide in the former Yugoslavia and in Rwanda.
Neither, ICTY (the International Criminal Tribunal for the Former Yugoslavia) or ICTR (the International Criminal Tribunal for Rwanda) has been a rousing success by anyone's standards. While ICTY was in the midst of an extended trial of former Yugoslav President Slobodan Milosevic when this essay was written, many of the most notorious Serbian leaders avoided capture for years, including General Ratko Mladic and former Prime Minister Radovan Karadzic of the Republika Srpska, which was allegedly responsible for most of the atrocities. The Rwandan situation is different. As many as 200,000 men have been detained, many of them since shortly after the genocide in 1994. Neither the Rwandan government nor the ICTR has the resources to try so many people, let alone deal with the social and political consequences of any such number of convictions of people who killed their fellow citizens, most often by using machetes.
To avoid the use of ad hoc courts such as these, ensure due process and the rule of law in war crimes cases, and to deter future war crimes, the international community created the International Criminal Court (ICC). The Statute of Rome, which gave birth to the Court, was approved by a vote of 120 to 7 of UN member states in July 1998. By April 2002, the required 60 countries had ratified the treaty (the number had topped 75 by the end of 2002), and the Court was therefore formally created in July 2002. It will only have jurisdiction over crimes committed after that date and only if states do not initiate cases in domestic courts. It will, however, provide a permanent tribunal before which large-scale crimes against humanity can be pursued. It, too, is controversial.
A number of important countries had not ratified the treaty by the end of 2002, including the United States, Russia, China, and Iraq. The United States (an original signatory of the Rome Statute) has been outspoken in its opposition ever since the Bush Administration took office and formally "unsigned" it in early 2002. Even though most legal experts think there are adequate guarantees to the contrary, Washington has claimed that American troops, including its peacekeepers, could be subject to arbitrary harassment and prosecution under its provisions.
Some critics argue that war crimes tribunals suffer the same major flaw as all of international law. Indictments may be issued, and some trials may be held. However, the international legal system lacks adequate enforcement mechanisms to arrest and otherwise implement whatever decisions it makes, especially since so many large and internationally engaged states have refused to enter the ICC system.
Finally, as in Rwanda, where so many average citizens have been caught up in war crimes charges, there is growing support to deal with the cases through restorative justice rather than international criminal law. Tens of thousands of prosecutions could place an impossible burden on any country's legal system and could actually deepen the divisions left after the end of the fighting. As a result, a number of countries (including Yugoslavia and Rwanda) are considering versions of a truth and reconciliation commission to handle the cases of all but the worst perpetrators of war crimes.
Why Are War Crimes Important
War crimes are important because they have been committed in virtually every war fought in recent decades. The reasons for that range from the spread of deadlier weapons, which make the killing of citizens and "collateral damage" all but unavoidable, to the intense racial, ethnic, and religious hatred that underlies many of today's disputes. In short, intractable conflict seems to bring massive human rights abuses in its wake. Not dealing with the crimes of war, then, only deepens the anger that gave rise to the fighting and in so doing lays the groundwork for even bloodier battles in the future.
What Citizens Can Do
On one level, there is little that average citizens can do about war crimes. Once a case reaches one of the tribunals, it becomes the province of a tiny band of attorneys who have mastered the thousands of pages of documents underlying the ICC and the rest of the statutes and precedents underlying international criminal law.
On another level, popular involvement is all-important. Wars, including war crimes, in far-off parts of the world receive very little attention in the Western mass media. And, because crimes against humanity often never appear on our "radar screens," there is little public pressure to do anything about them.
Today, fortunately, it is relatively easy for people to inform themselves about human rights violations, including war crimes, on the World Wide Web. Traditional organizations such as Amnesty International and Human Rights Watch have broadened their missions to include some of the issues that fall under the ICC's jurisdiction. And, Crimes of War is but the most important of the NGOs, which routinely investigate and publicize alleged instances of gross violations of human rights. Without that kind of an informed public, it seems highly unlikely that pressures to strengthen the international regime combating war crimes will grow.
What States Can Do
The ICC, the UN, and other international courts are part of what international relations experts call a "regime," a collection of rules, institutions, and norms that bring a degree of order to a rather disorderly system of global politics. As suggested earlier, however, the regime has more than its share of problems. And, in an international system which is still largely dominated by states as far as reaching new international agreements is concerned, their support will be needed if more "teeth" are to be added to the ICC and other legal institutions.
At the very least, the United States, Russia, China, Iraq, and the other 100-plus countries, which have not ratified the ICC treaty, must do so. It may well be that the treaty will have to be modified or other "side agreements" reached before these reluctant powers feel comfortable joining.
Even more importantly, states that are parties to the regime have to do what they can to strengthen it. That means using all the moral, legal, and political power at their disposal to make certain that alleged violators of international criminal law are prosecuted and punished if convicted. Moreover, as has happened in the development of other international regimes (e.g., international trade or telecommunications), states can play a critical role in creating an environment in which support for new powers and new members grows.
What Third Parties Can Do
Similarly, third parties, including the international legal institutions themselves, have a vital role to play. Despite the refusal of the United States and the other countries to join the ICC, the overall trend since the end of the Cold War has been for international courts to gain, not lose, influence. While the realists are no doubt correct when they claim that international courts lack the enforcement power of their domestic equivalents, some, including the various European courts, do have considerable power. Even more importantly, the international legal institutions and third parties in general have contributed to the growing realization that war crimes are a serious problem. After all, it is barely half a century since the first war-crimes tribunals were convened.
 Both in Graham Evans and Jeffrey Newnham, Penguin Dictionary of International Relations. (London: Penguin, 1996), 567-8.
Use the following to cite this article:
Hauss, Charles (Chip). "War Crimes ." Beyond Intractability. Eds. Guy Burgess and Heidi Burgess. Conflict Information Consortium, University of Colorado, Boulder. Posted: September 2003 <http://www.beyondintractability.org/essay/war-crimes-general>.