Nearly a quarter of Cambodia’s population died from the mass atrocities committed by the Khmer Rouge between 1975 and 1979. After the full picture of the atrocities was revealed, the international community responded with deep sympathy. Efforts to return justice to victims and their families, however, have been protracted. It was not until the establishment of the UN-backed tribunal, the Extraordinary Chambers in the Courts of Cambodia (ECCC), that the legitimate judicial proceedings to hold the Khmer Rouge accountable for their crimes began. The joint effort of the Cambodian government and the UN converges with the ethos of the Responsibility to Protect.