A/HRC/7/56 page 10 28. Renewed and active efforts by the Office to establish a working relationship with the President of the Governmental Cambodian Human Rights Committee during the last quarter have evoked no response. D. Impunity 29. Combating impunity is one of the main priorities of the United Nations High Commissioner for Human Rights worldwide. Since November 2007, the Office has started to monitor the proceedings of the Extraordinary Chambers in the Courts of Cambodia (ECCC), set up to try senior Democratic Kampuchea leaders and those most responsible for crimes committed during the dark period (1975-1978). The role of the Office in this respect is to follow the ECCC proceedings so as to identify good practices and model proceedings that could be imported as sources of awareness, education and inspiration for judges, prosecutors and lawyers in the wider justice system, and to contribute to a dynamic that will address crimes of recent years which are still unpunished. 30. Impunity has been identified by previous Special Representatives of the Secretary-General for human rights in Cambodia as the single most important obstacle undermining the rule of law in Cambodia. In this regard, 2007 has witnessed positive developments in addressing some of the crimes of the past. On the positive side, the authorities moved to arrest three former Khmer Rouge soldiers accused of implication in the murder of a British mine clearance expert and his Cambodian interpreter in 1996. 31. During the summer, the ECCC adopted its internal rules, proceeded to arrest four additional leaders of the former Democratic Kampuchea, and held its first hearing in the case of the former head of the notorious S-21 interrogation and execution centre. These developments have created a new, more positive dynamic at the ECCC, which has facilitated cooperation between the Cambodian and international elements and has had widespread resonance with the public; for the first time in the country’s history, senior public officials are being brought to account for their past crimes. 32. The year 2007 has however witnessed serious setbacks or lack of progress in bringing to justice those responsible for a long list of unsolved killings since 1993. Of this list, the case of trade union leader Chea Vichea is only the most well-known. These cases, as well as the phenomenon of impunity, its roots and adverse consequences for the rule of law and justice in Cambodia, were analysed in detail in a 2005 report of the Special Representative of the Secretary-General for human rights in Cambodia, which remains a landmark contribution to understanding the continuing patterns of impunity in Cambodia. 33. In April 2007, the Office monitored the appeal of Born Samnang and Sok Sam Ouen, the two men convicted of the murder of Chea Vichea. The court of appeal decided to uphold the convictions, in spite of the overwhelming body of evidence indicating that the men are innocent. The case is emblematic for what it reveals about impunity for crimes which appear to possess a political dimension, the independence of the judiciary, the ability of the courts to render effective remedies for human rights violations and for the underlying concern it raises about trade union freedoms in Cambodia. In addition to the Chea Vichea murder and the murder of Ros Sovannareth in 2004, the Office monitored the case of a third murdered trade union leader, Hy Vuthy, in March 2007. Mr. Hy was the local president at a factory in Phnom Penh of the