The defendant, a 20-year-old retarded woman, is accused of biting a counselor who was trying to get her in out of the rain.

"You've heard what the plaintiff said," says her lawyer, who has put her on the witness stand in her own defense. "Did you understand what she said?"

"Yeah."

"Do you like the rain?"

"No, my father don't want me to get sick."

"If you don't like the rain, why didn't you come back in [when the counselor called her?"]

"Somebody was teasing me."

"If they were bothering you, why bite the counselor?"

"Don't want to stay there anymore . . . I want to move when I grow up."

Minutes later, the defendant is found guilty by the presiding Judge. Her sentence: to apologize.

"Will you do that?" asks the judge.

She nods her head and says, "Yes."

The scene is perhaps the most unusual court in Northern Virginia -- a conference room at the Northern Virginia Training Center, a rambling and secluded state-run facility on Braddock Road in Fairfax County for the mildly and profoundly retarded.

The lawyers and judge are practicing attorneys, volunteers in a six-month-old experiment to give 140 or so of the center's least retarded residents a chance to learn to accept responsibility for their actions.

It is believed to be the first project of its kind in the county, and its backers consider it a success.

"The rights of the mentally retarded have been abridged for years," said center director David Lawson, a cofounder of the project. "When you treat people as children, they act like children."

The proceedings -- officials don't like to call them trials, although they have many of the trappings, down to lawyers scratching on yellow legal pads -- are voluntary for accused and accuser alike. Both the Virginia attorney general and the Fairfax County Human Rights Committee have blessed the hearings, which do not have the force of law.

Residents, staff members and even outsders -- like the merchants at nearby shopping centers, who occasionally catch a resident stealing -- can initiate complaints, but most cases so far have been in-house.

For example, one resident accused another of stealing money from her purse twice. Ordered by the judge to apologize (the money had been returned), the unrepentant defendant had a one-word reply: "Bull." But he agreed to fulfill his sentence.

"We tailor the hearings to things the resident can understand," said Lawson. "Let's say Billy busts a window. As a penalty, he may have to contribute a token amount to the residents' fund. He gets experience in a limited way that tells him, if you do something wrong, you have to pay for it." l

The new system also helps remove some residents' suspicions that the staff, which once functioned in effect as accuser, jury and judge, was out to get them, officials said.

The center is home to 285 people ranging in age from 18 months to 65. When Lason and Fairfax lawyer Michael J. Valentine set up the project last December, 56 residents were judged likely to benefit from the experience. lThe apparent success of the trials has prompted the staff to include another 84 people as potential participants.

Among those praising the experiment are many of the Fairfax attorneys who donate their time. "I think it's agreat program," said lawyer Gail Schultze. "These hearings are a small area of normalization."

They are also small windows on the world of the retarded, where frustration and anger can lead quickly to antisocial behavior. According to the staff member's testimony in the biting incident:

"We were coming back to the (living) unit from the cafeteria. (The defendant) refused to do so. She was being disruptive. I completed the meds (medicine prescribed for residents subject to seizures or other problems). She was still being disruptive. I put her in physical restraint (a prone position face down with arms behind the back, a technique approved for calming patients).

The young woman broke away. The counselor tried to hold her down again, but again was unsuccessful.

"What happened?" asked her volunteer attorney, Gaylor L. Finch Jr.

"She bit me on both arms."

Two perfect impressions of teeth on the arms were the evidence.

It is the kind of case the courtroom experiment is intended to resolve peacefully. Asked if she wanted to appeal her sentence of making an apology, the resident conferred with her lawyer, then said she did not.

"Residents now have an alternative way of dealing with complaints against each other," said Lawson. "They don't have to use their fists."