After a decade of tedious negotiations and delays, the former Khmer Rouge officer Kaing Guek Eav—known to the world as “Duch”—has finally been brought to trial.While in charge of a notorious Khmer Rouge prison camp in the late 1970s, Duch oversaw the systematic mass murder of approximately 15,000 inmates. Now he sits in a Phnom Penh courtroom, watching his own fate unfold.

Some might say that the actions of an evil but long-gone Cambodian regime 30 years ago have little bearing on the world of today. But the Khmer Rouge’s brutal genocide, which eliminated about one-fourth of Cambodia’s population, deserves to be prosecuted accordingly.

Even though Duch himself cannot possibly account for more than a small fraction of Khmer Rouge atrocities, it is important to recognize the regime’s crimes on an individual basis through international law. While the 10 years of disorganization between Duch’s discovery in 1999 and the beginning of his trial this past week leave much to be desired in terms of legal procedure, it is comforting that the tribunal prosecuting Duch in Phnom Penh has been organized with the support of the United Nations.

Though it might be difficult to determine proper punishment for a man who killed and ordered the deaths of so many fellow citizens, we are glad to see that the death penalty will not be an option. Fortunately, in the system that will try Duch and other former Khmer Rouge officials, criminals will be brought to justice with the humanity and due process that their victims were denied.

In this vein, it is essential that Duch be offered a fair trial. This week, there has been much debate as to whether to allow Norng Chan Phal, a rare survivor of Duch’s infamous S-21 camp, to be part of the prosecution, even though he missed the filing deadline by two days. While it may seem harsh, Phal should be excluded. The rules—trivial as they may seem— must be upheld above all else. The trial must be conducted with meticulous attention to legal procedure as a tribute to Duch’s prisoners, who were never given such an opportunity.

There is no way to truly make amends for the cold, calculated murder of one-fourth of a nation’s people. But the trial of Kaing Guek Eav allows at least some measure of justice for the atrocities of the Khmer Rouge.