When Kevin E. was an 8-year-old welfare patient at St. Elizabeths Hospital, someone caught him one day climbing into a trash can. Asked what he was doing, the boy said he was worthless and wanted to be thrown away.

In a way, he already had been, advocates for 2,200 children in the District's child welfare system said in federal court yesterday. The advocates have filed a class-action suit on behalf of the children against the D.C. Division of Child and Family Services, and yesterday, on the first day of trial, city officials said little to rebut the allegations.

The lawsuit alleges that the city is violating children's constitutional rights, that the system is overworked and underfunded, and that instead of taking abused children away from their parents and putting them up for adoption, it simply warehouses them for years in foster care.

Kevin is an example, said lawyers with the New York-based Children's Rights Project of the American Civil Liberties Union.

He entered the District's child welfare system in 1979 when he was 19 days old. Today, he is still in the system, a veteran of five foster homes and a residential facility in Baltimore. Several families have offered to adopt him, but the city has never taken the legal steps necessary to free him for adoption. His mother, who was 15 when he was born, refuses to give him up voluntarily. She has also beaten him and locked him in a dark bathroom. Kevin has once tried suicide by banging his head against a wall.

"Kevin's story is not unusual," Marcia Robinson Lowry, head of the Children's Rights Project, said in court yesterday. "These children have been left without a childhood, left without a chance to grow into productive adults."

The lawsuit paints a picture of a chaotic system overwhelmed with the needs of its abused children, and without the staff to offer services to help troubled families reunite.

Officials with the D.C. Department of Human Services, which oversees the Child and Family Services Division, declined to comment on the suit. But they have said problems in the foster care system are the result of a lack of funds.

A brief filed yesterday on the District's behalf also asserts that, when it comes to child abuse in the family, the city is not ultimately responsible. It relies on a 1989 Supreme Court ruling holding that states cannot be held constitutionally liable for harm done to children by their parents.

ACLU lawyers say their lawsuit -- and eight others it has filed like it elsewhere -- is the only path to reform. Lowry has said the District's child welfare system is one of the nation's worst. Among their findings in a pre-trial statement:

The average length of stay in foster care in the District was 58 months in 1989, while the national average for 1985, the last year for which figures are available, was 26 months.

Children placed in emergency care custody, which by law is supposed to last only 90 days, often spend years in that status. Babies placed by the city at a facility in Hyattsville, for instance, frequently don't leave until they are walking.

As of last October, nearly half of the 275 staff positions at Child and Family Services were vacant, the result of budget cutbacks. Of the 170 social workers there, the suit says, caseloads range from 60 to 200 children per worker.

Because of staffing shortages at the D.C. Corporation Counsel's Office, city lawyers spend most of their time filing initial child neglect petitions and almost no time filing motions to terminate parental rights. Without the latter, no child is legally free for adoption. Many would-be adoptive families won't take the emotional risk of taking in a child whose natural parents could turn up at the last minute to assert their rights.

There aren't enough caseworkers to recruit adoptive families. Of the nearly 2,200 children in District foster homes last year, plaintiff's lawyers say, only 69 were legally adopted, down from 72 in 1985.

Years of uncertainty spent in foster care wreak devastation on children's self-esteem, the ACLU lawyers say. Among the voluminous files submitted in preparation for the trial are case histories of such children, drawn from the city's records.

Among those stories is that of Meeka, 9, and her sister, Tanya, 2, whose mother left them one day at the home of a boyfriend's relative and never came back.

"The children were found walking the streets alone, looking for old friends," the ACLU's case history states. Meeka had packed a suitcase of dirty clothes for their journey. Today, 22 months later, the girls are still in foster care, with no immediate prospect of adoption.

Then there was Tyrone F., 3, who came to the attention of social workers in 1984 when a neighbor complained that Tyrone's mother was locking him and his siblings in an empty house, filthy and unfed. Three years later, when he was still in foster care, his mother called to say she was going to pay him a visit on his birthday.

Tyrone dressed up and waited all day. She never came.

Six months later, Tyrone tried to kill himself. In December 1989, when Tyrone's mother moved to Georgia, she managed to regain custody of Tyrone, but somewhere in the move, Tyrone simply got lost.

His current whereabouts are unknown, the ACLU report states.

The trial before U.S. District Judge Thomas F. Hogan is expected to last until next week.