The term crimes against humanity has come to mean anything atrocious committed on a large scale. This is not, however, the original meaning nor the technical one. The term originated in the 1907 Hague Convention preamble, which codified the customary law of armed conflict. This codification was based on existing State practices that derived from those values and principles deemed to constitute the “laws of humanity,” as reflected throughout history in different cultures.

After World War I, the Allies, in connection with the Treaty of Versailles, established in 1919 a commission to investigate war crimes that relied on the 1907 Hague Convention as the applicable law. In addition to war crimes committed by the Germans, the commission also found that Turkish officials committed “crimes against the laws of humanity” for killing Armenian nationals and residents during the period of the war. The United States and Japan strongly opposed the criminalization of such conduct on the grounds that crimes against the laws of humanity were violations of moral and not positive law.

In 1945, the United States and other Allies developed the Agreement for the Prosecution and Punishment of the Major War Criminals of the European Axis and Charter of the International Military Tribunal (IMT), sitting at Nuremberg, which contained the following definition of crimes against humanity in Article 6(c):

“Crimes against humanity: murder, extermination, enslavement, deporta tion, and other inhumane acts committed against civilian populations, before or during the war; or persecutions on political, racial or religious grounds in execution of or in connection with any crime within the jurisdiction of the Tribunal, whether or not in violation of the domestic law of the country where perpetrated.”

The Nuremberg Charter represents the first time that crimes against humanity were established in positive international law. The International Military Tribunal for the Far East, at Tokyo, followed the Nuremberg Charter, as did Control Council Law No. 10 of Germany, under which the Allies prosecuted Germans in their respective zones of occupation. Curiously, however, there has been no specialized international convention since then on crimes against humanity. Still, that category of crimes has been included in the statutes of the International Criminal Tribunal for the former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR), as well as in the statute of the International Criminal Court (ICC). In fact, there are eleven international texts defining crimes against humanity, but they all differ slightly as to their definition of that crime and its legal elements. However, what all of these definitions have in common is: (1) they refer to specific acts of violence against persons irrespective of whether the person is a national or non-national and irrespective of whether these acts are committed in time of war or time of peace, and (2) these acts must be the product of persecution against an identifiable group of persons irrespective of the make-up of that group or the purpose of the persecution. Such a policy can also be manifested by the “widespread or systematic” conduct of the perpetrators, which results in the commission of the specific crimes contained in the definition.

The list of the specific crimes contained within the meaning of crimes against humanity has been expanded since Article 6(c) of the IMT to include, in the ICTY and the ICTR, rape and torture. The statute of the ICC also expands the list of specific acts. In particular, the ICC statute adds the crimes of enforced disappearance of persons and apartheid. Further, the ICC statute contains clarifying language with respect to the specific crimes of extermination, enslave- ment, deportation or forcible transfer of population, torture, and forced pregnancy.

To some extent, crimes against humanity overlap with genocide and war crimes. But crimes against humanity are distinguishable from genocide in that they do not require an intent to “destroy in whole or in part,” as cited in the 1948 Genocide Convention, but only target a given group and carry out a policy of “widespread or systematic” violations. Crimes against humanity are also distinguishable from war crimes in that they not only apply in the context of war—they apply in times of war and peace.

Crimes against humanity have existed in customary international law for over half a century and are also evidenced in prosecutions before some national courts. The most notable of these trials include those of Paul Touvier, Klaus Barbie, and Maurice Papon in France, and Imre Finta in Canada. But crimes against humanity are also deemed to be part of jus cogens—the highest standing in international legal norms. Thus, they constitute a non-derogable rule of international law. The implication of this standing is that they are subject to universal jurisdiction, meaning that all States can exercise their jurisdiction in prosecuting a perpetrator irrespective of where the crime was committed. It also means that all States have the duty to prosecute or extradite, that no person charged with that crime can claim the “political offense exception” to extradition, and that States have the duty to assist each other in securing evidence needed to prosecute. But of greater importance is the fact that no perpetrator can claim the “defense of obedience to superior orders” and that no statute of limitation contained in the laws of any State can apply. Lastly, no one is immune from prosecution for such crimes, even a head of State.