It was considered a hybrid court, as the ECCC was created by the government in conjunction with the UN, but remained independent of them, with trials being held in Cambodia using Cambodian and international staff.

The chief purpose of the tribunal as identified by the Extraordinary Chambers was to provide justice to the Cambodian people who were victims of the Khmer Rouge regime's policies between April 1975 and January 1979.

[2] Upon the denial of Khieu Samphan's appeal, and with no other living senior members of the Khmer Rouge to indict, the tribunal concluded in December 2022, with three convictions in all.

[3][4] In 1997, Cambodia's two Co-Prime Ministers wrote a letter to the Secretary-General of the United Nations requesting assistance to set up trial proceedings against the senior leaders of the Khmer Rouge.

[5] In May 2006, Justice Minister Ang Vong Vathana announced that Cambodia's highest judicial body approved 30 Cambodian and United Nations judges to preside over the long-awaited genocide tribunal for surviving Khmer Rouge leaders.

[10] All international judges were appointed by the Supreme Council of the Magistracy of Cambodia from a list of nominees submitted by the Secretary-General of the United Nations.

The role of the OCP was to prosecute the senior leaders of the Khmer Rouge and others most responsible for the crimes committed during the period of Democratic Kampuchea.

The OCP processed victim complaints; conducted the preliminary investigations (first investigatory stage); and issues Introductory Submissions to the Office of Co-Investigating Judges where there was sufficient evidence of crimes within the jurisdiction of the ECCC having been committed.

The OCP also participated in the judicial investigations (second investigatory stage), filing Supplementary Submissions as necessary when new facts came to light and original allegations required additions or amendments.

[33] Victims of the Khmer Rouge were defined as "any person or legal entity who has suffered from physical, psychological, or material harm as a direct consequence of the crimes committed in Cambodia by the Democratic Kampuchea regime between 17 April 1975 and 6 January 1979 that are under the jurisdiction of the ECCC".

Victims had the opportunity to actively participate in judicial proceedings through Complaints and Civil Parties, and they could seek collective and moral reparation.

“The tribunal facilitates reconciliation and at the same time provides an opportunity for Cambodians to come to terms with their history,” ECCC spokesman Neth Pheaktra said in an interview with D+C.

His lieutenant Mam Nay, the feared leader of the interrogation unit of the Santebal, gave testimony on 14 July 2009 and, although implicated in hands-on torture and execution along with Duch, he was not charged.

[57] During the rule of the Khmer Rouge, Nuon Chea, party's chief ideologist, acted as the right-hand man of leader, Pol Pot.

[58] Nuon Chea joined the Communist Party of Kampuchea (the Khmer Rouge's official name) while studying law at Thammasat University in Bangkok.

[60] Although Chea is the highest-ranking official to be detained he denies the majority of his involvement in the Khmer Rouge: "I was president of the National Assembly and had nothing to do with the operation of the government.

[61] On 7 August 2014, in Case 002/1, the Trial Chamber found Nuon Chea guilty of numerous crimes against humanity and sentenced him to life imprisonment.

[65][66] On 22 November 2019, the Supreme Court Chamber clarified notably that Nuon Chea's death did not vacate the trial judgment against him and that, although the presumption of innocence applies at the appeal stage, it does not equate to post mortem finding of not guilty.

When the regime fell in 1979, Ieng fled to Thailand and was convicted of genocide and sentenced to death by the People's Revolutionary Tribunal of Phnom Penh.

[77] The investigation in Case 003 focuses on the crimes committed by Meas Muth, high-ranking member of the Revolutionary Army of Kampuchea (RAK) during the period from 17 April 1975 to 6 January 1979.

The National Co-Investigating Judge issued an order dismissing all the charges against Meas Muth on the ground that he is not one of the most responsible for the crimes committed during the Khmer Rouge regime.

The Pre-Trial Chamber unanimously responded that "having fulfilled all its duties in accordance with the ECCC’s legal framework, including the Cambodian Code of Criminal Procedure, intends to stand by its Considerations.

It categorically refuses to be associated, through the actions of confused Co-Investigating Judges or requests that have already been granted, with malpractices that have provoked such failure that it now seems insurmountable to those who have caused it."

When the Khmer Rouge took control of Phnom Penh on April 17, 1975, Yim Tith was appointed as the party secretary for Kirivong district (in Sector 13).

The National Co-Investigating issued an order dismissing all the charges against YIM Tith on the ground that he is not one of the most responsible for the crimes committed during the Khmer Rouge regime.

[19] Pre-Trial Chamber's Case 004 Considerations issued on 17 September 2021, Judges Kang Jin BAIK and Olivier BEAUVALLET underlined the continued absence of genuine prosecutorial effort by the Cambodian authorities and recalled that, as a state party to the Genocide Convention, the Royal Government of Cambodia has an obligation to ensure that Khmer Rouge cadres charged with genocide are prosecuted and tried by a competent court of justice.

They added that considering the evidence collected in Cases 003 and 004, the national authorities are "indubitably obligated to take on the responsibility to prosecute the Defendants should the ECCC not proceed further".

[93] According to a survey conducted by the International Republican Institute, 67% of the respondents replied that they "very much agree" with a trial against the top Khmer Rouge leaders.

Many international critics say these closings stem from a reluctance by the Cambodian government to try Khmer Rouge officials who managed to switch alliances towards the end of the conflict.

A trial monitor for the OSJI claimed that the recent proceedings "don't meet basic requirements or adhere to international standards or even comply with the court's own prior jurisprudence.