Cambodia's parliament has ratified legislation to set up a UN-backed tribunal to put leaders of the murderous Khmer Rouge regime on trial.
More than 1m people died under Khmer Rouge rule
The tribunal, which has been delayed by political infighting within Cambodia, will be the first chance for the regime's leaders to face justice.
It will include Cambodians and foreigners, but still needs funding.
More than 1m Cambodians died from starvation, disease or execution under the Khmer Rouge's 1975-79 rule.
Cambodia's National Assembly voted by 107-0 to ratify the tribunal, which has been under discussion for more than five years.
"What we have been waiting for so long has happened today," Prime Minister Hun Sen said after the vote.
KHMER ROUGE TRIBUNAL
Will try cases of genocide and crimes against humanity
Five judges (three Cambodian) sit in trial court
Cases decided by majority
Maximum penalty is life imprisonment
The delays, and a 11-month political stalemate in Cambodia, had raised fears that none of the Khmer Rouge's ageing leaders would face justice.
Its main architect, Pol Pot, died in 1998.
Former army chief, Ta Mok, and chief interrogator Kaing Khek Iev, are the only two senior figures currently in detention awaiting trial.
Other leaders, including head of state Khieu Samphan, foreign minister Iang Sary, and Nuon Chea, known as "Brother Number Two", are still free.
The UN-backed tribunal will be made up of Cambodian and foreign legal experts, with Cambodians in the majority.
Cambodian and foreign analysts have welcomed the tribunal's establishment.
But there are worries that it will not be free of interference from the Cambodian government, some of whose members fought for the Khmer Rouge.
There has also been criticism that, by focussing on a few high-profile leaders, the tribunal, will allow lower-ranking Khmer Rouge leaders who were also involved in serious crimes to escape justice.
Funding for the tribunal has yet to be agreed. Cambodia's Foreign Minister, Hor Namhong, last week urged the UN to help find funds for half of the $50m tribunal.
So far, only Australia has pledged to donate more than $2m.
It was not clear how quickly the tribunal would be able to begin work.
It still needs to be approved by the Senate and King Norodom Sihanouk, although these are expected to be formalities.