Crimes against humanity have both a colloquial and a legal existence. In daily parlance, the term is employed to condemn any number of atrocities that violate international human rights. As a legal construct, crimes against humanity encompass a constellation of acts made criminal under international law when they are committed within the context of a widespread and systematic attack against a civilian population. In the domain of international criminal law, crimes against humanity are an increasingly useful component of any international prosecutor’s toolbox, because they can be charged in connection with acts of violence that do not implicate other international criminal prohibitions, such as the prohibitions against war crimes (which require a nexus to an armed conflict) and genocide (which protects only certain human groups and requires proof of a specific intent to destroy such a group). Although the concept of crimes against humanity has deep roots, crimes against humanity were first adjudicated—albeit with some controversy—in the criminal proceedings following the World War II period. The central challenge to defining crimes against humanity under international criminal law since then has been to come up with a formulation of the offense that reconciles the principle of sovereignty—which envisions an exclusive territorial domain in which states are free from outside scrutiny—with the idea that international law can, and indeed should, regulate certain acts committed entirely within the borders of a single state. Because many enumerated crimes against humanity are also crimes under domestic law (e.g., murder, assault, and rape), it was necessary to define crimes against humanity in a way that did not elevate every domestic crime to the status of an international crime, subject to international jurisdiction. Over the years, legal drafters have experimented with various elements in an effort to arrive at a workable penal definition. The definitional confusion plaguing the crime over its life span generated a considerable amount of legal scholarship. It was not until the UN Security Council promulgated the statutes of the two ad hoc international criminal tribunals—the International Criminal Tribunal for the Former Yugoslavia and the International Criminal Tribunal for Rwanda—that a modern definition of the crime emerged. These definitions were further refined by the case law of the two tribunals and their progeny, such as the Special Court for Sierra Leone. All these doctrinal developments were codified, with some additional modifications, in a consensus definition in Article 7 of the Statute of the International Criminal Court (ICC). It is now clear that the offense constitutes three essential elements: (1) the existence of a widespread or systematic attack against a civilian population and (2) the intentional commission of an enumerated act (such as an act of murder or torture) (3) by an individual with knowledge that his or her act would contribute to the larger attack. A renewed effort is now afoot to promulgate a multilateral treaty devoted to crimes against humanity based on the ICC definition and these central elements. Through this dynamic process of codification and interpretation, many—but not all—definitional issues left open in the postwar period have finally been resolved. Although their origins were somewhat shaky, crimes against humanity now have a firm place in the canon of international criminal law.
A Prosecution too far? Reflections on the Accountability of Heads of State under International Criminal Law