Senator Jack Reed, a Rhode Island Democrat who called the hearing, said that the topic required more attention, potentially in further hearings.
Republicans at the hearing said they, too, supported strong reforms.
Peter Paul Biro, at the same hearing, said, "I don't specifically recall the circumstances".
Black, in his only remark after the hearing, said he was "not surprised" by the ruling.
"We didn't have a hearing," said Kevin O'Toole, himself the son of a Korean mother.
Politicians in court for the hearing said it did not go well for the government.
"I think we put up with not hearing," said the actor.
"She's going to have a vigorous hearing," said Senator Tom Coburn, Republican of Oklahoma, in a telephone interview Tuesday.
"I am not happy with this hearing," said Mr. Nuon Chea, who is described as the Khmer Rouge's chief ideologue.
"He (Mr Kark) advises us in the strongest terms that these cases cannot proceed to a hearing," said Mr Dickson.
But the frustrated teachers, soft-spoken students and former football players who stood up at the hearing said otherwise.
