International criminal law is the body of public international law that establishes individual criminal responsibility for international crimes, such as war crimes, crimes against humanity, genocide, and aggression.
The exact definition of an international crime remains debated, but it is normally understand as an act that violates fundamental interests of the international community and entails individual criminal responsibility. The generally accepted core international crimes are war crimes, crimes against humanity, Crimes against humanity encompass serious attacks on human dignity when committed as part of a widespread or systematic attack against a civilian population. Under Article 7 of the Statute of the International Criminal Court such crimes may be committed during times of armed conflict and peace. For further information, see G. Acquaviva and F. Pocar, ‘Crimes against Humanity’, Max Planck Encyclopedia of Public International Law, 2008 (restricted access). genocide, Defined in Article 2 of the 1948 Convention on the Prevention and Punishment of the Crime of Genocide, genocide may be committed by acts such as murder or serious bodily harm with intent to destroy, in whole or in part, a national, ethnical, racial or religious group. For further information, see W. Schabas, ‘Genocide’, Max Planck Encyclopedia of Public International Law, 2007 (restricted access). and aggression. Pursuant to the 2010 Kampala Amendments to the Statute of the International Criminal Court, an act of aggression that constitutes a manifest violation of the prohibition to use force may be prosecuted under certain circumstances as the crime of aggression once the amendment enters into force. Depending on the concept of international crimes used, other criminalized conduct such as piracy or torture may also be considered an international crime. For an overview of the debates concerning the definition and concept of international crimes, see the International Crimes Database, TMC Asser Institute, The Hague.
Many violations of international humanitarian law are nowadays considered war crimes. Criminal prosecutions for war crimes are a means to implement international humanitarian law . Other judicial and quasi-judicial implementation mechanisms may include bodies which deal with state responsibility. The list of such bodies would include the International Court of Justice, human rights courts, namely the European Court of Human Rights, the Inter-American Court of Human Rights, and the African Court on Human and Peoples’ Rights, and the United Nations treaty bodies. However, international humanitarian law is broader than the concept of war crimes: not every violation of international humanitarian law constitutes a war crime.
The current system of international criminal law works through international ad hoc tribunals, Ad hoc tribunals are tribunals established to prosecute international crimes committed in specific contexts. The International Criminal Tribunal for the former Yugoslavia was created for the purpose of prosecuting persons responsible for international crimes committed in the territory of the former Yugoslavia since 1 January 1991, and the International Criminal Tribunal for Rwanda was established to try persons responsible for international crimes committed between 1 January 1994 and 31 December 1994, that is during the Rwandan genocide. mixed or hybrid tribunals, Hybrid tribunals, such as the Special Court for Sierra Leone and the Special Tribunal for Lebanon combine features of international ad hoc tribunals and domestic courts and apply both international and national law. and the International Criminal Court, as well as national courts. One of the legal consequences of framing an act as an international crime is that it may give rise to what is called universal jurisdiction: pursuant to the principle of universal jurisdiction, any state is allowed to try alleged perpetrators of international crimes, even in the absence of any link between the accused and the state exercising jurisdiction.
The genesis of international criminal law as a branch of international law can be traced back to the London Charter of the International Military Tribunal adopted in 1945. Since then, and especially over the past two decades with the proliferation of various ad hoc tribunals and the establishment of International Criminal Court, international criminal law has developed considerably.
Statutes of international tribunals are the main treaties that are used by international criminal courts as a legal basis and guidelines for their activities, most importantly the Statute of the International Criminal Court. Other treaties include international instruments directly criminalizing certain types of conduct, such as the Convention on the Prevention and Punishment of the Crime of Genocide, and conventions which may be taken into account for the identification of customary criminal rules. The 1949 Geneva Conventions with their Additional Protocols may serve both purposes.
Customary international law may fill in the gaps, where treaties do not contain explicit criminal norms. Such norms can be inferred from the jurisprudence of both international and domestic tribunals. See ICTY, The Prosecutor v Dusko Tadić, Appeals Chamber, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, IT-94-1-AR72, 2 October 1995, §§96-99.
War crimes are serious violations of international humanitarian law that entail individual criminal responsibility. War crimes can only be committed during times of armed conflict, either international or non-international, as understood under international humanitarian law. Crimes against humanity and genocide often take place against the background of an armed conflict, but it is not necessary to establish the existence of an armed conflict for their prosecution. The same criminal act, for example torture, may constitute a war crime, a crime against humanity, and genocide, provided that the overall requirements of these crimes are fulfilled. While it is necessary that the crime in question was committed during an armed conflict, this is in itself not sufficient: the crime must be sufficiently linked to the armed conflict. This so-called nexus requirement is satisfied if the armed conflict played a substantial role in the perpetrator’s decision to commit the crime, his or her ability to commit it, or the manner in which the crime was committed. See ICC, The Prosecutor v Thomas Lubanga Dyllo, Pre-Trial Chamber I, Decision on the Confirmation of Charges, ICC-01/04-01/06, 29 January 2007, §§287-288; ICC, The Prosecutor v. Germain Katanga and Mathieu Ngudjolo Chui, Pre-Trial Chamber I, Decision on the Confirmation of Charges, ICC-01/04-01/07, 30 September 2008, §§380-382. For more information on the nexus requirement, see A. Schwarz, ‘War Crimes’, Max Planck Encyclopedia of Public International Law, 2014 (restricted access).
In order to define an act as a war crime, this act must, besides having nexus to an armed conflict, be a serious violation of international humanitarian law and entail individual criminal responsibility. During international armed conflicts, the Geneva Convention of 1949 and the Additional Protocol I thereto of 1977 criminalize a certain number of acts as ‘grave breaches’, Article 50 of the First Geneva Convention; Article 51 of the Second Geneva Convention, Article 130 of the Third Geneva Convention, Article 147 of the Fourth Geneva Convention, and Article 85 of the Additional Protocol I. and oblige state parties to prosecute individuals responsible for such acts. Thus, the grave breaches automatically qualify for both criteria of seriousness and criminalization. Acts that are not defined as grave breaches must be examined on a case by case basis. As for the seriousness criterion, according to the Tadić decision by the International Criminal Tribunal for the Former Yugoslavia, a violation is serious enough if it constitutes a breach of a rule protecting important values and involves grave consequences for the victim. ICTY, The Prosecutor v Dusko Tadić, Appeals Chamber, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, IT-94-1-AR72, 2 October 1995, §94. The second criterion is the criminalization of the act. According to the same decision and further jurisprudence, the violation of the rule must entail the individual criminal responsibility under customary or conventional law. ICTY, The Prosecutor v Dusko Tadić, Appeals Chamber, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, IT-94-1-AR72, 2 October 1995, §94; ICTY, The Prosecutor v Stanislav Galić, Trial Chamber, Judgment, IT-98-29-T, 5 December 2003, §§113-137.
The International Criminal Court is a permanent international court established by the 1998 Rome Statute to investigate, prosecute, and try alleged perpetrators of war crimes, crimes against humanity, genocide, and the crime of aggression. To date, more than 120 countries have ratified the Statute. In addition to setting out the crimes that fall within the jurisdiction of the Court, the Statute provides for the conditions under which the Court may exercise jurisdiction. It may exercise jurisdiction over crimes committed by nationals of state parties or in the territory of these state parties since the date of entry into force of the Rome Statute for the state party in question.
In addition, the United Nations Security Council can refer a situation to the International Criminal Court, triggering its jurisdiction and extending it to countries that may not be parties to the 1998 Rome Statute. See for example the United Nations Security Council resolution 1593 referring the situation in Darfur to the International Criminal Court, UNSC Res 1593, 31 March 2005.