When a federal judge ruled here nearly eight years ago that handicaped and emotionally disturbed children have a constitutional right to a public education, his landmark decision was a legal promise to those youngsters that they no longer would be excluded from the classroom because of of their special needs.

But lawyers for those children were back in the U.S. District Court last week, reciting a litany of cases that they contend prove that the District government has deliberately ignored the order by the late Judge Josepc C. Waddy. City officials deny the allegations.

There is the case of K.G., 14, borderline mentally retarded, emotionally disturbed and learning disabled. Accourding to Waddy's order, a special education plan and placement for K.G. should have been proposed by school officials within 50 days, but six months passed without a placement. In the meantime, K.G. was arrested for several juvenile offenses, according to court records filed in November. He was sent to Cedar Knoll, the city's minimum security facility for young offenders.

Michael and Michelle R., both mentally retarded, attend the city's Grimke Job Development Center, a special education school in Northwest Washington. A 1979 school system report recommended that the Grimke program be shut down. The report said the school has antiquated plumbing, architectural barriers to the handicapped and "dehumanizing" toilet facilities. Some children there have been misdiagnosed as mentally retarded, court records said. Grimke remains open, the lawyers said, although it violates Waddy's order for appropriate education services for those children.

An emotionally disturbed 12-year-old Durante B., was diagnosed as needing 24-hour residential care, which his grandmother requested from the school system. In the five months before an evaluation was complete, Durante attempted suicide and was admitted to St. Elizabeth Hospital. He was placed in a shelter care facility primarily for runaways and drug offenders. His lawyers contend that is because the school system has a policy against residential treatment, in violation of Waddy's order.

Special education services are not a "right " in the District as Waddy's order said, argued Robert Plotkin, an attorney with the Mental Health Law Project who has handled the children's case since 1974. Instead, such services are "closely guarded privileges" for those children whose parents have the "fortitude and money" to bread down bureaucratic barriers in the city government.

Lawyers for the children want Judge John Gorrett Penn to find school officials in the contempt of court for the second time since 1975, when Waddy made the same finding. At that time a special master was appointed to try to prepare ways to enforce Waddy's ruling. A final plan was approved by Waddy in 1978 Now, the children's lawyers complain of continued violatins. The city government says it is constrained by its budget and that the children's lawyers are reading more requirements into Waddy's order than were intended.

"You can't ask anybody to do something that's impossible," contended Assistant D.C. Corporation Counsel Hugh Stevenson during arguments before Judge Penn on Friday.

The D.C. Board of Education and the Department of Human Resources have mad a "good faith" attempt to comply with "unrealistic" placement deadlines set by Judge Waddy, Stevenson said. And compliance, he said, has always been hampered by a shortage of staff and "an extremely difficult budget situation. Tight money should be blamed on Congress," which appropriates funds to the District for special education.

"We go up there, we ask for money and we come back with nothing," Stevenson said.

Stevenson said the case of Durante B. illustrates the school system's problem in deciding whether a child has an emotional problem, which might require hospital treatment, or whether his needs can be met through a special education placement, under the terms of Waddy's order.

The school system has made an effort to correct deficiencies at the Grimke school, Stevenson said. He said that there was testimony during the hearing that Grimke is an interim program and that children there will eventually be transferred to a new school.

Between 4,000 and 6,000 children receive special education services at 50 schools in the District, ranging from an hour of extra reading help to residential care, according to testimony presented during five days of hearings before Judge Penn. In 1979, congress appropriated $16 million to the District for special education services, which was supplemented by another $3.2 million in grant money.

Special education programs, partly spurred by federal laws and the court orders, have developed from an effort to guarantee an education to the nation's handicapped children as far as possible by "mainstreaming" them -- placing them in regular classrooms.

Stevenson told Penn that only 60 school system employees are available to screen 11,000 cases referred each year for special education evaluation as well as counseling and other services.

The city said that in the 1978-79 school year, 91 percent of its proposed placements were not made within Waddy's 50-day deadline. The city government has asked Penn to extend those deadlines.

Stevenson also denied that the school system has a policy against residential placements for children. Waddy's order, he contended, makes no reference to residential treatment, but instead emphasizes that the education needs of these children be met through the public school system.

Moreover, Stevenson said, nothing in Waddy's decision requires that specific types of eductional programs be set up for the children -- as their lawyers contend.

Penn took the issues under advisement and said he will issue a written opinion in the case.