Chum Mey, one of the few survivors of Tuol Sleng prison, is also one of the civil parties participating in Khmer Rouge tribunal proceedings.

As the pre-trial detention hearing of jailed Khmer Rouge leader Ieng Sary came to a close this week, participants found themselves at odds over how much victim participation through civil parties was too much.

Prior to one session of the hearings, the Pre-Trial Chamber judges ruled that one individual, Seng Theary, a Cambodian-American lawyer whose parents died under the Khmer Rouge, would not be allowed to participate directly. Pre-trial judges ruled that for the Ieng Sary hearings, civil party victims of the regime would only be allowed to express themselves through lawyers.

That ruling has raised questions over how much participation should be allowed in the future.

The UN-Cambodia tribunal was designed with a unique element: the presence of civil parties, who participate alongside prosecutors and the defense, representing their own cases but also speaking as a voice of the victims. But following the hearings Thursday, lawyers told reporters there was a limit.

"In some ways, it was really a bad week from the perspective of the civil parties," said lawyer for the civil parties Silke Studzinsky. "We received this week a ruling by the Pre-Trial Chamber saying that civil parties are not allowed to speak personally if they are not represented."

Under the tribunal's internal rules, civil parties are not obligated to have a lawyer, Studzinsky said.

Seng Theary called the ruling "a prevention of the civil parties' rights."

Michael Karnavas, co-defense for Ieng Sary, disagreed.

"We still have not set up the modality, how far can [civil parties] go, what should they do?" he said Thursday. "Half the time they are just repeating the arguments that the prosecutors made, rather than say, 'I concur,' and then adding one or two points."

However, Studzinsky said Karnavas was used to working with courts in a system of common law, unlike the system used to set-up the tribunal.

William Smith, co-deputy prosecutor, called civil parties very important for the tribunal. They play a watchdog role, he said, and stand up for the interest of all victims.

Tribunal spokesman Reach Sambath said the role of the civil parties was important to the courts, but in some cases, testimony such as Seng Theary's is not crucial.

"Seng Theary's case is not the same," he said. "The expression of the victims in person will be more interesting in the trials."