What you need to know:
- Analysts generally agree that the ICTR succeeded in holding accountable some of the key organisers of the atrocities committed against Rwanda's Tutsi minority in 1994.
- If captured, Mr Kabuga and two other top-level fugitives will be put on trial by the UN Mechanism for International Criminal Tribunals, a smaller-scale successor to the ICTR.
International law experts are giving a mixed appraisal of the International Criminal Tribunal for Rwanda, which formally concluded its operations on December 31 after 21 years of judging cases involving genocide.
Analysts generally agree that the ICTR succeeded in holding accountable some of the key organisers of the atrocities committed against Rwanda's Tutsi minority in 1994.
"It is extremely important to prosecute the highest-level perpetrators through fair trials," says Prof Jennifer Trahan, author of a book on ICTR case law.
The tribunal indicted 93 individuals linked to the genocide that claimed an estimated 800,000 lives.
All of those charged were said to have organised or perpetrated the slaughter of Tutsi.
In what some analysts describe as the tribunal's greatest failure, none of its cases involved the killings of Hutu civilians that were allegedly directed by Tutsi leaders.
The ICTR handed down guilty verdicts in 61 cases, including those of former Prime Minister Jean Kambanda, former army Chief of Staff Gen Augustin Bizimungu and former Defence Ministry Chief of Staff Col Théoneste Bagosora.
Tribunal judges — cases were tried without juries — acquitted 14 suspects. Eight of those accused of genocide remain fugitives, including Felicien Kabuga, an alleged financier of some of the mass killings.
He has been reported over the years to be hiding in Kenya, but the Kenyan government has dismissed those claims.
If captured, Mr Kabuga and two other top-level fugitives will be put on trial by the UN Mechanism for International Criminal Tribunals, a smaller-scale successor to the ICTR.
The UN Security Council, which authorised the ICTR, last week hailed the "substantial contribution" the tribunal has made to "the fight against impunity and the development of international criminal justice, especially in relation to the crime of genocide.”
ICTR President Vagn Joensen pointed out in remarks to the Security Council that the tribunal had rendered the first international judgment of genocide against a head of government. It was also the first international court to recognise rape as a means of perpetrating genocide, he noted.
But the absence of prosecutions related to documented massacres of Hutu has led to criticisms that the ICTR delivered "victor's justice."
Yolande Bouka, a Nairobi-based researcher with the Institute for Security Studies, notes that the Security Council had given the ICTR jurisdiction over acts of genocide, crimes against humanity and war crimes committed in Rwanda between January 1994 and December 1994.
"The fact that the tribunal did not fully investigate and prosecute crimes allegedly committed by the RPA during that period is a significant failure of the ICTR," Ms Bouka wrote in an email to The East African.
She was referring to the Rwanda Patriotic Army, the Tutsi-led guerrilla force that routed Hutu perpetrators of atrocities.
Human Rights Watch said in a report earlier this year that "certain kinds of [RPA] abuses occurred so often and in such similar ways that they must have been directed by officers at a high level of responsibility."
Ms Bouka recalls that Carla del Ponte was replaced as the ICTR's chief prosecutor in 2003 after attempting to investigate crimes allegedly carried out by Tutsi. Ms del Ponte charged at the time that her ouster resulted from pressures applied by the Rwandan government.
The tribunal has also drawn criticisms for the length of time and the amount of money spent in carrying out its work.
Trials lasted an average of four years, with one running for nine years. The total cost of financing the ICTR came to $2 billion.
"The proceedings moved too slowly," comments Richard Dicker, director of the international justice programme at Human Rights Watch.
Ms Trahan, author of "Genocide, War Crimes and Crimes Against Humanity: A Digest of the Case Law of the International Criminal Tribunal for Rwanda," notes that "prosecuting large-scale atrocity crimes involving multiple perpetrators and multiple crime scenes is not an inexpensive endeavor, nor [is] creating a tribunal from scratch."
Ms Bouka, a Rwandan specialist at the South Africa-based think tank, adds that the ICTR became more efficient as it gained experience.
Some analysts further suggest that the ICTR achieved a greater measure of thoroughness and fairness than did the special courts, known as Gacaca, established inside Rwanda to try local figures said to have taken part in the genocide. The Gacaca ceased operating in 2012.
Human Rights Watch had "serious issues with the Gacaca in terms of selectivity of prosecutions."
Mr Dicker says. "There were also problems involving fairness and protection of the rights of the accused."
Ms Bouka notes that "some of the first individuals to be arrested, tried, and convicted of genocide [by the Gacaca] were executed without providing the world with much information about the intricacies of their role or what they knew about others involved in the genocide."
The Rwandan government initially advocated establishment of an international tribunal to handle at least some of the cases arising from the 1994 slaughters.
But Rwanda's UN representative voted against the Security Council resolution authorising the ICTR partly on the grounds that it should have been empowered to investigate what occurred in the four years leading up to the genocide.
Rwanda had also wanted the tribunal to be given the option of imposing the death penalty. The ICTR should have been based in Rwanda, the government further maintained.
Asked what lessons might be relevant to future tribunals, such as the hybrid courts proposed for South Sudan, Mr Dicker said it will be crucial to hold accountable those "most responsible on both sides of the conflict."
Similarly, mechanisms established in South Sudan must be designed to "minimise political interference from outside the courts," he said.