Anyone can summarize it please into 300 or 400 words. International crimes - Introduction Introduction Initial notions of the concept of international crimes began to emerge in the Roman Empire with the writings of jurist Marcus Tullius Cicero and the concept of hostes humani generis, the enemies of humanity. This concept was used by writers as from the 17th century to refer to the perpetrators of international crimes such as piracy and slavery.[1] However, it was not until the Nuremberg and Tokyo tribunals - set up after the Second World War to prosecute leaders accused of serious crimes - that some crimes became criminalized under international law and the foundation for what we currently refer to as international criminal law was laid. In the 1948 Hostages case, an international crime was defined as “such an act universally recognized as criminal, which is considered a grave matter of international concern and for some valid reason cannot be left within the exclusive jurisdiction of the state that would have control over it under ordinary circumstances”, see p. 10 of this document. With the creation of the International Criminal Tribunal for the former Yugoslavia (ICTY), the International Criminal Tribunal for Rwanda (ICTR), the International Criminal Court (ICC) and several other internationalised or hybrid criminal courts, international crimes have been prosecuted and the concept of international crimes started developing and is still evolving as we speak. Over the years, this development has been guided and supported by the International Law Commission (ILC). More than six decades later, it has been generally agreed upon that certain crimes, such as war crimes, crimes against humanity, genocide and the crime of aggression are considered to have the status of ‘international crimes’. At the same time, the label of ‘international crime’ has proven quite controversial. Many scholars, such as Cassese,[2] Cherif Bassiouni[3] and Werle,[4] have written about the intriguing question: what constitutes an international crime? Despite many efforts, scholars disagree as to the answer to this fundamental question. Some scholars argue that international crimes are those crimes committed by individuals or state agents, while others claim that they can also include crimes perpetrated by corporations. Finally, there are also those who do not provide a definition of international crimes in their work at all.[5] While several acts have been recognised as international crimes and can be prosecuted in both national co