IN LATE FEBRUARY at Oak Hill, the District's detention center for teen-agers, a 17-year-old boy refused an order to wear his sweater under his jacket. He was wearing it over the jacket. For that act of defiance, he was charged with "inciting to riot." That night, without a hearing on the charge, he was sentenced to solitary confinement in a locked, cell-like room for seven days. During that time he would be allowed out for two hours a day to bathe and exercise, but he wuld not be able to go to school or to eat in the dining hall. The next morning, in a hearing without any adult counsel, the youth was found guilty of the charge and his sentence was confirmed: seven days in solitary confinement.

But that was not the end of his story. During a trip out of his cell the next day to take a bath, he slipped into the kitchen and drank a carton of milk. He was charged with theft, which meant another seven days of solitary confinement -- 14 days in all. However, after seeing him kept in confinement for nine days for not wearing a sweater properly and for swiping milk, officials at the institution decided to let him out.

This incident is not uncommon at the city's detention centers for juveniles, Oak Hill and Cedar Knoll. About 25 young people were placed in solitary confinement at Oak Hill during the first two months of this year. The number confined at Cedar Knoll is not known; reports are not always filed on cases there. Nevertheless, from staff members and people associated with the institutions come stories of adolescents being kept in isolation for minor infractions. And the confinement often comes without benefit of a hearing to determine if the young person is even guilty of the charges. In fact, the hearings are regularly held after the youth has begun to serve his sentence. In one recent case at Cedar Knoll, two youngsters, did not get a hearing for nine days while the maximum sentence for their violtion was seven days. "Nothing to do in there but sleep and figure on gettin' even, says one young man who has spent time in solitary at Oak Hill. "If you try to get up and say you going to do something, you'll be going crazy because there ain't nothing to do. I was flushing the toilet for something to do."

Under the 1976 Savoy order, issued by Judge Harold Greene, any youngster placed in lockup at the institutions is entitled to a hearing before being locked up as well as to having an adult represent him at the hearing. The young person is also to have the right to cross-examine any witnesses at the hearing.Typically, these rules are ignored as the inmates, many of whom can't read, are slipped a sheet of paper explaining their rights and are told to sign it. They all sign the paper, most evidently without understanding that they are signing away their rights, accepting a sentence to confinement. Even after confinement, the young person theoretically is entitled to appeal the decision under rules set forth by the Savory Order. But that has not been done in years because the offenders do not know that the appeal procedure exists. No one tells them.

The city's Department of Human Services, which runs Oak Hill and Cedar Knoll, should end the use of solitary confinement and the shameful rules and hearings that pass for justice at these institutions. And it should do so now. There is no sense in which these cruel practices can qualify as useful punishment for the rough, disturbed kids who find themselves in the District's care.