Two months after he was put in charge of the juvenile courts in Prince George's County, Circuit Judge David Gray Ross called probation officers together and told them to cut their caseloads, sometimes as high as 90, to less than 20.

Lawyers and parents of juvenile offenders received equally surprising news. Ross told attorneys he would grant no delays in their cases and told parents they would have to pay court costs of $85, which traditionally had been waived. And he told dozens of juvenile repeat offenders that they would have to stand trial as adults.

Now, nearly two years after the 47-year-old former state delegate began what court watchers call a streak of efficiency, Ross continues to awe, please and infuriate those who come before him. The more than 3,000 cases that go through the court are heard many times more quickly than they ever were before, and the number of children in detention has plummeted by more than 60 percent, to 34, as a result. The amount collected from juvenile offenders and their parents in restitution and court costs has quadrupled.

Such streamlining has brought glowing praise from one of the judge's predecessors, who says, "Ross is an administrative genius." But it also has prompted charges from some attorneys and county officials who say Ross' methods are insensitive to the needs of children.

Ross cites arrest figures as evidence that his tactics are an effective deterrent. While the number of juveniles arrested for major crimes has been falling across the country, at a rate of about 9 percent a year according to the U.S. Justice Department, the number of juveniles arrested for major crimes in Prince George's fell by 15 percent in 1981, and 15 percent more last year, from 3,838 in 1980 to 2,757.

Juveniles once waited four to six months from the time of their arrests to the day of sentencings. That too has changed. Between June 1981 and June 1982, the average time between filing a juvenile case and sentencing was 50 days, compared with 238 days in Montgomery County, and a statewide average of 112 days. Almost 70 percent of juveniles in Prince George's were sentenced within two weeks. There's a much longer waiting time for most juveniles in the District, Alexandria, and Fairfax and Arlington counties, court officials in those jurisdictions say.

"The punishment is more meaningful," says a Ross admirer, James Dedes, supervisor of juvenile services in the county. "It's closer to the time that the actual incident occurred." There is also less chance for a juvenile to commit additional offenses while awaiting punishment, Ross observes.

With fewer cases, says Prince George's County's other juvenile judge, Robert J. Woods, judges can do a better job.

But Ross' efficiency has also earned him a great many critics. "There is a quantitative approach rather than qualitative," says James S. Nicholsporn, a public defender in juvenile court. He agrees that Ross has made the courts "cheap and quick," but asks, "is this for the good of the respondent? The community? Or is it for the good of the court?"

Many criticize Ross' policy of waiving more juveniles to adult court, a national trend that had passed Prince George's County by until Ross took over. In 1980, the year before Ross came to the juvenile bench, 62 juvenile cases were transferred to adult court. The next year, 148 cases were waived, and in 1982, there were 145.

Sending children to adult court deprives them of the help available in the juvenile system, says Albert W. Northrop, a Bowie lawyer and chairman of the county's Juvenile Court Advisory Committee. Richard J. Bury, another public defender, says his greatest criticism is that juveniles are held in adult jails. "I've got two 16-year-olds on waivers, sitting in the adult prison doing absolutely nothing but trying to defend themselves against whatever happens in there."

Some complain that Ross' inactive probation also deprives juveniles of needed help and guidance. Under active probation juvenile offenders receive frequent visits from probation officers who closely monitor what they do at home, school and elsewhere. Inactive probation simply means once children arrive in court, their parents are warned they could be liable for up to $5,000 for damages their children might cause, and are told to contact the courts if there are any future problems. Ross says "a very small number do." No contact is made with probation officers.

Before Ross began his system of inactive probation, there were between 1,100 and 1,200 children on probation. That number has fallen to 661. There are about 400 on inactive probation at any one time.

Ross says probation officers previously were so overloaded they concentrated on children they liked best, and could tell the courts nothing about the others. In addition, he argues, probation officers too often keep a child on probation longer than necessary and "hound him in the name of counseling for four years." Under his new system, he says, at least the judge decides which children get attention.

"From an administrative point of view, it's the greatest thing that could happen to us," says Dedes, who maintains that probation officers concentrated on children in crisis, not on the ones they liked best. He notes, however, that the 42 probation officers could "comfortably" handle about 35 cases each, almost twice the number Ross allows them.

Gary Clark, a juvenile services counselor for eight years, says he resigned last April "purely because I was disgusted with the direction that the court system was taking." He says he felt Ross sidestepped the problem of providing care and services by putting children on inactive probation or sending them to adult court.

With the huge drop in the number of children on probation, he says, probation officers wondered what their purpose was. "Some of us became very bitter and combative," he said. "I know I did."

Hollis R. Weisman, head of the state's attorney's juvenile division, praises Ross for waiving more children to adult court, but complains that inactive probation is "not even like a slap on the wrist." If a juvenile on inactive probation gets in trouble, she says, "they are placed on active probation. They don't even get locked up . . . . In many cases I think the probation has been terminated too quickly and we have found they have committed an offense right after."

One 17-year-old who appeared in court last week on assault charges has a history of court appearances for fighting and destroying property beginning a year and a half ago. He has a "hot temper," he acknowledged in an interview after his court appearance. "I've been trying to change," he said. "I need help. I know I do."

The three other times this boy has been through the county's juvenile justice system, one case was dropped before going to court, a second case, for assault, was dismissed despite the fact that he pleaded guilty, and the third time he was given inactive probation.

The youth said he did not know what inactive probation meant until his brother explained it to him several days after sentencing. Asked what inactive probation means, the boy replied: "It means I can go out and enjoy my fun . . . . It was good: I got off that charge . . . . It means you are getting off scot-free."

Nicholsporn, who represented the youth in his last court appearance, said the youth's history is "a classic example" of the juvenile courts' failure to deal with the problems children have. Now, less than a month before the youth's 18th birthday, after which he would be tried as an adult, Judge Ross has ordered psychiatric, psychological and sociological reports on him.

Ross says the court is using a limited number of probation officers as effectively as possible. "Would it be nice to have a probation officer for them all? Sure," he says. "But we don't have the money."

No other jurisdiction in the Washington area, or in all of Maryland, has inactive probation for juveniles. In Montgomery County, where juvenile probation officers handle about 40 cases each, juvenile services supervisor Jane Whitt says she cannot recall a case where a Montgomery judge has taken a child off probation against probation officers' recommendations.

Ross' ideas about inactive probation are "consistent with the trend," says William Minor, a University of Illinois criminologist preparing a study of repeat offenders in Prince George's. "There's an effort to focus limited resources more on the people most likely to benefit from them," he says. "But "it's not the kind of thing that judge's publicize very much . . . "because of "political opposition."

But if children are getting off lighter, as people such as Weisman contend, more parents are paying the price in cash. Court costs are now imposed almost without exception. In the first nine months of this year, the juvenile court collected $64,451 in costs--420 percent more than in the same period of 1980.

The court must remind families that it is not a "free right, where we slap everyone on the wrist and tell them to go home," Woods says. He rarely waives the court costs, he says, even if the family is poor. If it's a "really good family" he may drop costs because that family won't need an $85 bill to remind them they have a problem to deal with. But if it's a "bad family," he says, "I'd probably make them pay: it makes the family know that crime doesn't pay."

This policy infuriates Nicholsporn, who says imposing court costs on poor families is "reprehensible," and amounts to fining parents. He notes some "typical" cases of parents charged $85, all from one day two weeks ago.

* A mother with four dependent children, earning only $260 a month, according to income declarations made while applying for a public defender.

* A mother of five earning $461 a month.

* Another mother of four, making $166 a week.

* An unemployed father with seven dependants, whose only declared income was $200 a month from his deceased wife's Social Security benefits.

"I don't feel the sanction of $85 for court costs against the parents for a three- to five-minute admonishment from the bench is sufficient to change the life of these youngsters," Nicholsporn says.

Running a juvenile justice system on a tight budget is at the heart of many of the changes Ross has made. Last week, his colleague Woods summoned dozens of parents whose children are juvenile offenders living in group homes under court custody and asked them to help pay.

"The reason we are here is that all this costs money," Woods told one mother, whose son is in a group home costing more than $10,000 a year per child. "We are in bad times . . . . We only have so much money to spread around."

The woman agreed to pay $60 a month, and make the payment by Jan. 20. The judge looked at the book in front of him. "Could you do it by the 19th?" he asked.