(Source picture: Juniki San/Wikipedia)
The term ‘genocide’ was first coined by Raphael Lemkin, a Polish-Jewish lawyer. On p. 79 of his 1944 book Axis Rule in Occupied Europe: Laws of Occupation – Analysis of Government – Proposals for Redress, he wrote:
New conceptions require new terms. By “genocide” we mean the destruction of a nation or of an ethnic group. This new word, coined by the author to denote an old practice in its modern development, is made from the ancient Greek word genos (race, tribe) and the Latin cide (killing) (…) [.]
After the Shoah (the genocide of the Jews during the Second World War), the United Nations (UN) General Assembly (GA) adopted Resolution 96(1) of 11 December 1946 ('the Crime of Genocide'), in which it affirmed:
[G]enocide is a crime under international law which the civilized world condemns, and for the commission of which principals and accomplices – whether private individuals, public officials or statesmen, and whether the crime is committed on religious, racial, political or any other grounds – are punishable[.]
Two years later, the UN GA adopted Resolution 260 (III) (‘Prevention and Punishment of the Crime of Genocide’) A (‘Adoption of the Convention on the Prevention and Punishment of the Crime of Genocide, and Text of the Convention') of 9 December 1948. Article I of the Convention on the Prevention and Punishment of the Crime of Genocide stipulates that "[t]he Contracting Parties confirm that genocide, whether committed in time of peace or in time of war, is a crime under international law which they undertake to prevent and to punish." The 'Genocide Convention' now has 152 States Parties, which indicates that the idea that genocide is an international crime is shared by the majority of States in this world.
The definition of genocide that can be found in Article II of the 1948 ‘Genocide Convention’ has been followed by the statutes of the International Criminal Tribunal for the former Yugoslavia (see its Art. 4, para. 2), the International Criminal Tribunal for Rwanda (see its Art. 2, para. 2) and the International Criminal Court (see its Art. 6) and clarifies that genocide means:
any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such: (a) Killing members of the group; (b) Causing serious bodily or mental harm to members of the group; (c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part; (d) Imposing measures intended to prevent births within the group; (e) Forcibly transferring children of the group to another group.
Recent well-known genocides occurred in Rwanda (1994) and in Srebrenica (1995). For instance, on 2 September 1998, Trial Chamber I of the ICTR found Jean-Paul Akayesu guilty of, among other things, genocide, which was the first conviction ever for this international crime. Two days later, the same Trial Chamber I convicted and, for the first time in history, sentenced a person, Jean Kambanda, to life imprisonment for genocide, among other things. On 2 August 2001, Trial Chamber I of the ICTY concluded “that the intent to kill all the Bosnian Muslim men of military age in Srebrenica constitutes an intent to destroy in part the Bosnian Muslim group within the meaning of Article 4 and therefore must be qualified as a genocide” (see para. 598 of this judgment) and for the first time found an accused, Radislav Kristić, guilty of, among other things, genocide, see para. 645 of the same judgment. On 10 June 2010, Trial Chamber II of the ICTY noted “that genocide was committed by members of the Bosnian Serb Forces (…) against the Muslims of Eastern Bosnia, as part of the Bosnian Muslims [original footnote omitted]”, see para. 863 of this judgment, and found Vujadin Popović and Ljubiša Beara guilty of, among other things, genocide (see pp. 832-833 of the same judgment), and Drago Nikolić guilty of aiding and abetting genocide, among other things, see p. 834 of the same judgment. The genocide in Srebrenica was also recognized by the International Court of Justice, see para. 297 of this judgment, which concluded that Serbia, as the first State in history, had violated the Genocide Convention by failing to prevent and to punish genocide, see para. 450 of the same judgment.
Finally, the ICC has also initiated its first genocide case. On 12 July 2010, Pre-Trial Chamber I of the ICC issued a (second) warrant of arrest against Sudanese President Omar Al Bashir, finding that there were reasonable grounds to believe that Al Bashir was criminally responsible for three counts of genocide – namely genocide by killing, genocide by causing serious bodily or mental harm and genocide by deliberately inflicting on each target group conditions of life calculated to bring about the group’s physical destruction – committed against the Fur, Masalit and Zaghawa ethnic groups in Darfur.
 For other sources mentioning genocide as an international crime, see, e.g., I. Brownlie, Principles of Public International Law, Sixth Edition, Oxford University Press: Oxford 2003, pp. 561-562; A. Cassese, International Criminal Law, Oxford University Press: Oxford 2003, p. 24; R. Cryer et al., International Criminal Law and Procedure, Cambridge University Press: Cambridge 2007, p. 2.