thumb|upright=1.1|In 1915, the [[Armenian genocide (pictured) was officially condemned as a "crime against humanity" by Russia, France, and the United Kingdom.]]

Crimes against humanity are certain crimes committed as part of a large-scale attack against civilians. Unlike war crimes, crimes against humanity can be committed during both peace and war and against a state's own nationals as well as foreign nationals. Together with war crimes, genocide, and the crime of aggression, crimes against humanity are one of the core crimes of international criminal law and, like other crimes against international law, have no temporal or jurisdictional limitations on prosecution (where universal jurisdiction is recognized).

Origins of the term

The term "crimes against humanity" may cover one or both meanings of the word "humanity": the quality of being human and humans as a whole. In the context of the Nuremberg trials, documents suggest the former sense was primarily intended, being parallel to the concept of "crimes against peace", although scholars have also noted that the second meaning was sometimes present as well.

thumb|[[Leopold II of Belgium|Leopold II, King of the Belgians and de facto owner of the Congo Free State, whose agents were accused of crimes against humanity]]

The term is first attested in 1883, when American minister, politician and historian George Washington Williams used it in his reflections about slavery in the United States. In his first annual message in December 1889, U.S. President Benjamin Harrison also spoke about the slave trade in Africa as a "crime against humanity". The term "crimes against humanity" was used again by Williams in a letter he wrote to the United States Secretary of State describing the atrocities in the Congo Free State committed by Leopold II of Belgium's administration in 1890. This is often popularly cited as the first use of the term in its modern sense in the English language, despite Williams' earlier usage.

In treaty law, the term was first used in the Second Hague Convention of 1899 preamble and was expanded in the Fourth Hague Convention of 1907 preamble and their respective regulations, which were concerned with the codification of new rules of international humanitarian law. The preamble of the two Conventions referenced the "laws of humanity" as an expression of underlying, unarticulated humanistic values. The term is part of what is known as the Martens Clause.

On 24 May 1915, the Allied Powers, Britain, France, and Russia, jointly issued a statement explicitly and for the first time ever charging another government with committing "a crime against humanity". An excerpt from this joint statement reads:

At the conclusion of the war, the Allied Commission of Responsibilities recommended the creation of a tribunal to try "violations of the laws of humanity" because the law of war did not cover atrocities committed by a state against its own nationals or allied persons. The US representative subsequently objected to references to the "law of humanity" as being imprecise and insufficiently developed at that time, so the concept was not pursued.

A UN report in 1948 referred to the usage of the term "crimes against humanity" regarding the Armenian genocide as a precedent to the Nuremberg and Tokyo trials. On 15 May 1948, the Economic and Social Council presented a 384-page report prepared by the United Nations War Crimes Commission (UNWCC), set up in London (October 1943) to collect and collate information on war crimes and war criminals.

Nuremberg trials

thumb|right|300px|Nuremberg Trials. The defendants are in the dock. The main target of the prosecution was [[Hermann Göring (at the left edge on the first row of benches), considered to be the most important surviving official in the Third Reich after Hitler's death.]]

After the Second World War, the Nuremberg Charter set down the laws and procedures by which the Nuremberg trials were to be conducted. The drafters of this document were faced with the problem of how to charge the men at the Nuremberg Trial with committing the Holocaust and other state-sanctioned atrocities committed in Germany and German-allied states by the Nazi regime. As far as German law was concerned, the men had committed no crime but only followed orders. In Nazi Germany, not following orders was a crime punished severely. The problem in trying the individuals responsible for the German atrocities lay in the fact that, like in World War I, a traditional understanding of war crimes gave no provision for atrocities committed by a state on its own citizens or its allies.

Under this definition, crimes against humanity could be prosecuted and punished, even as ex post facto infractions, only insofar as they could be connected somehow to war crimes or crimes against peace. The judgement of the first Nuremberg trial found that "the policy of persecution, repression and murder of civilians" and persecution of Jews within Germany before the outbreak of war in 1939 were not crimes against humanity, because as "revolting and horrible as many of these crimes were, it has not been satisfactorily proved that they were done in execution of, or in connection with", war crimes or crimes against peace. The subsequent Nuremberg trials were conducted under Control Council Law No. 10 which included a revised definition of crimes against humanity with a wider scope.

Tokyo trial

thumb|300px|The defendants at the Tokyo International Tribunal. General [[Hideki Tojo was one of the main defendants and is in the centre of the middle row.]]

The International Military Tribunal for the Far East (IMTFE), also known as the Tokyo trial, was convened to try the leaders of the Empire of Japan for three types of crimes: "Class A" (crimes against peace), "Class B" (war crimes), and "Class C" (crimes against humanity), committed before and during the Second World War. The legal basis for the trial was established by the Charter of the International Military Tribunal for the Far East (CIMTFE) that was proclaimed on 19 January 1946. The tribunal convened on 3 May 1946, and was adjourned on 12 November 1948.

In the Tokyo Trial, Crimes against Humanity (Class C) was not applied for any suspect. Prosecutions related to the Nanking Massacre were categorised as infringements upon the Laws of War. A panel of eleven judges presided over the IMTFE, one each from victorious Allied powers (United States, Republic of China, Soviet Union, United Kingdom, the Netherlands, Provisional Government of the French Republic, Australia, New Zealand, Canada, British India, and the Philippines).

Types of crimes against humanity

The definition of a crime against humanity varies both between and within countries and it also varies on both the international and domestic levels. Isolated and inhumane acts of a certain nature which are not committed as part of a widespread or systematic attack may constitute grave infringements of human rights, or – depending on the circumstances – war crimes but they are not classified as crimes against humanity.

According to the Rome Statute, there are eleven types of crimes that can be charged as crimes against humanity when they are "committed as part of a widespread or systematic attack directed against any civilian population":

Apartheid

The systematic persecution of members of one racial group by members of another racial group, such as the persecution which was practiced by the South African apartheid government, was recognized as a crime against humanity by the United Nations General Assembly in 1976. The Charter of the United Nations, Articles 13, 14, 15 makes actions of the General Assembly advisory to the Security Council. In regard to apartheid in particular, the UN General Assembly has not made any findings, nor have apartheid-related trials for crimes against humanity been conducted.

Rape and sexual violence

The Nuremberg and Tokyo Charters did not contain any explicit provisions which recognized sexual and gender-based crimes as war crimes or crimes against humanity, but Control Council Law No. 10 recognized rape as a crime against humanity. The statutes of the International Criminal Tribunal for the former Yugoslavia and the International Criminal Tribunal for Rwanda both included rape as a crime against humanity. The ICC is the first international court which expressly includes various forms of sexual and gender-based crimesincluding rape, sexual slavery, enforced prostitution, forced pregnancy, enforced sterilisation, and other forms of sexual violenceas both an underlying act of crimes against humanity and a war crime which is committed during international and/or non-international armed conflicts.

In 2008, the U.N. Security Council adopted resolution 1820, which noted that "rape and other forms of sexual violence can constitute war crimes, crimes against humanity or a constitutive act with respect to genocide".

Unlike genocide and war crimes, which have been widely recognized and prohibited in international criminal law since the establishment of the Nuremberg principles, there has never been a comprehensive convention on crimes against humanity, even though such crimes are continuously perpetrated worldwide in numerous conflicts and crises. 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. In 2008, the Crimes Against Humanity Initiative was launched to address this gap in international law.

On 30 July 2013, the United Nations International Law Commission voted to include the topic of crimes against humanity in its long-term program of work. In July 2014, the Commission moved this topic to its active programme of work based largely on a report submitted by Sean D. Murphy (the Special Rapporteur for Crimes Against Humanity).

There is some debate on the status of crimes against humanity under customary international law. M. Cherif Bassiouni argues that crimes against humanity are part of jus cogens and as such constitute a non-derogable rule of international law.

After Nuremberg and the Tokyo trials, there was no international court with jurisdiction over crimes against humanity for almost 50 years. However, work continued on developing the definition of crimes against humanity at the United Nations. For instance, in 1947, the International Law Commission was charged by the United Nations General Assembly with the formulation of the principles of international law recognized and reinforced in the Nuremberg Charter and judgment, and they were also tasked with drafting a 'code of offenses against the peace and security of mankind'. Completed 50 years later in 1996, the Draft Code defined crimes against humanity as various inhumane acts, i.e., "murder, extermination, torture, enslavement, persecution on political, racial, religious or ethnic grounds, institutionalized discrimination, arbitrary deportation or forcible transfer of population, arbitrary imprisonment, rape, enforced prostitution and other inhuman acts committed in a systematic manner or on a large scale and instigated or directed by a Government or by any organization or group." This definition differs from the one used in Nuremberg, where the criminal acts were to have been committed "before or during the war", thus establishing a nexus between crimes against humanity and armed conflict.

On 21 March 2013, at its 22nd session, the United Nations Human Rights Council established the Commission of Inquiry on human rights in the Democratic People's Republic of Korea (DPRK). The Commission was mandated to investigate the systematic, widespread, and grave violations of human rights in the Democratic People's Republic of Korea (i.e. North Korea), with a view to ensuring full accountability, in particular for violations that may amount to crimes against humanity. The Commission dealt with matters relating to crimes against humanity on the basis of definitions set out by customary international criminal law and in the Rome Statute of the International Criminal Court. The 2014 Report by the Commission found "the body of testimony and other information it received establishes that crimes against humanity have been committed in the Democratic People's Republic of Korea, pursuant to policies established at the highest level of the State [....] These crimes against humanity entail extermination, murder, enslavement, torture, imprisonment, rape, forced abortions and other sexual violence, persecution on political, religious, racial and gender grounds, the forcible transfer of populations, the enforced disappearance of persons and the inhumane act of knowingly causing prolonged starvation. The Commission further finds that crimes against humanity are ongoing in the Democratic People's Republic of Korea because the policies, institutions and patterns of impunity that lie at their heart remain in place." Additionally, the Commission found that crimes against humanity have been committed against starving populations, particularly during the 1990s and that they were still being committed against persons from other countries who were systematically abducted or denied repatriation because they sought to gain labour and other skills for the Democratic People's Republic of Korea. The resolution commits the Council to action to protect civilians in armed conflict. In 2008 the UN Security Council adopted resolution 1820, which noted that "rape and other forms of sexual violence can constitute war crimes, crimes against humanity or a constitutive act with respect to genocide". Later, the United Nations claimed in its November 2019 report that the United Arab Emirates, Jordan and Turkey were then violating the arms embargo imposed on Libya under the 1970 resolution. An airstrike on the migrant detention center in Tripoli in July 2019, believed to have been carried out by the United Arab Emirates, can be amounted as a war crime, as stated by the United Nations. The airstrike was deadlier than the 2011 militarized uprising that overthrew the regime of Muammar Gaddafi.

International courts and criminal tribunals

After the Nuremberg and Tokyo trials of 1945–1946, another international tribunal with jurisdiction over crimes against humanity was not established for another five decades. In response to atrocities committed in the 1990s, multiple ad hoc tribunals were established with jurisdiction over crimes against humanity. The statutes of the International Criminal Court, the International Criminal Tribunals for the Former Yugoslavia and for Rwanda each contain different definitions of crimes against humanity.

International Criminal Tribunal for Yugoslavia

In 1993, the UN Security Council established the International Criminal Tribunal for the former Yugoslavia (ICTY), with jurisdiction to investigate and prosecute three international crimes which had taken place in the former Yugoslavia: genocide, war crimes, and crimes against humanity. Article 5 of the ICTY Statute states that:

This definition of crimes against humanity revived the original 'Nuremberg' nexus with armed conflict, connecting crimes against humanity to both international and non-international armed conflict. It also expanded the list of criminal acts used in Nuremberg to include imprisonment, torture and rape.

International Criminal Tribunal for Rwanda

The UN Security Council established the International Criminal Tribunal for Rwanda in 1994 following the Rwandan genocide. Under the ICTR Statute, the link between crimes against humanity and an armed conflict of any kind was dropped. Rather, the requirement was added that the inhumane acts must be part of a "systematic or widespread attack against any civilian population on national, political, ethnic, racial or religious grounds." Unlike the conflict in the former Yugoslavia, the conflict in Rwanda was deemed to be non-international, so crimes against humanity would likely not have been applicable if the nexus to armed conflict had been maintained.

Special Court for Sierra Leone

Extraordinary Chambers in the Courts of Cambodia (ECCC)

International Criminal Court

thumb|right|278px|Headquarters of the ICC in The Hague

In 2002, the International Criminal Court (ICC) was established in The Hague (Netherlands), and the Rome Statute provides for the ICC to have jurisdiction over genocide, crimes against humanity, and war crimes. ICC proceedings definitions of a "crime against humanity" have evolved significantly from its original legal definition or that used by the UN. Essentially, the Rome Statute employs the same definition of crimes against humanity that the ICTR Statute does, minus the requirement that the attack was carried out 'on national, political, ethnic, racial or religious grounds'. In addition, the Rome Statute definition offers the most expansive list of specific criminal acts that may constitute crimes against humanity to date.

The Rome Statute Explanatory Memorandum states that crimes against humanity: