
Attorneys for Kang Keng Iev, alias Duch, were expected to argue that detaining the 65-year-old for so long without trial breached his human rights and were expected to demand bail.
Duch, a born-again Christian, was discovered by photojournalist Nic Dunlop in 1999 working as a teacher in the north-western province of Battambang and has been imprisoned virtually since then.
He was in charge of the S-21 torture centre, or Toul Sleng, in Phnom Penh, where up to 14,000 people were "processed" and, if they survived, taken to the "killing fields" to be executed or worked to death in agricultural labour camps.
Duch has been formally charged with crimes against humanity by the joint UN-Cambodia tribunal, and security was tight as people crowded into the court Tuesday morning.
The hearing, expected to last two days with a verdict scheduled for release next month, is seen as the first step toward showing Cambodians that justice is finally moving forward, three decades after the 1975-79 regime was toppled.
Up to 2 million Cambodians perished under the Khmer Rouge's Democratic Kampuchea regime in its drive to turn the country into a classless agrarian utopia.
Four other former leaders have been charged by the court: former leader Pol Pot's chief deputy, Nuon Chea; former head of state Khieu Samphan; former deputy prime minister Ieng Sary; and his wife, Pol Pot's sister-in-law Khieu Thirith.//DPA