A new generation of school desegregation cases is about to begin. A federal appeals panel last week upheld a ruling that the Norfolk, Va., school board has fulfilled its duty to desegregate and can abandon a busing plan it has been following for 14 years, returning to neighborhood schools. Lawyers for some black plaintiffs are appealing. Of 36 elementary schools in the city, 10 will be all or nearly all black under the neighborhood plan where none was before. Perhaps a third of the black elementary children will attend these schools.

Many civil rights lawyers regard the new ruling with dismay. They argue that it is too early to start dismantling desegregation plans it took so long to win; they see the case as an invitation to resegregate all across the country, the more so because the Reagan Justice Department has taken up the Norfolk school board's cause, making it a symbol. But it distorts this case -- and the history of school desegregation -- to view it in such apocalyptic terms. The issue has been in the offing a long time. The civil rights groups have tried to ignore it. Now they can't.

1.The courts from the beginning have tried to distinguish between two kinds of school segregation, de facto and de jure. De jure is the kind they have sought to eradicate -- deliberate segregation by official means. The courts have been careful to point out that their purpose was not to achieve particular percentages of whites and blacks in the schools, but to eliminate all vestiges of so-called dual school systems. To do so might require a court or board to aim for certain percentages of whites or blacks into certain schools, but the percentages were not the goal. Achieving a "unitary" school system was.

2.Given this distinction, the Supreme Court for years has also said that there would someday come an end to the desegregation process, that offending districts would eventually work free of the official discrimination in their pasts, and that once they had, the courts should let them alone. In the important Swann case in 1971 -- the very case in which it said that courts could order offending school districts to bus -- the court also said "at some point" school districts could be expected to achieve compliance and "be 'unitary' in the sense required by our decisions." But the stopping point and process have never been defined.

3.The courts have also said the prospect of white flight is no excuse for not desegregating. If a district had a dual system and was ordered to bus, it was no defense to say that the busing would only drive whites across the district line and so be self- defeating. But a unitary system could be forgiven some accommodative steps to stop white flight.

The Norfolk case has been in the courts, off and on, for 30 years. It was not until 1971, after Swann, that the courts succeeded in pinning the city's resisting school board down. That year a busing plan was begun. By 1975, in an almost perfunctory order that seems more important in retrospect than it apparently did at the time, the district court held that Norfolk had achieved unitary status. But the busing plan was kept in place. In 1983, however, the board proposed to drop it. White flight was the reason openly given; the school district had gone from 57 percent white in 1970 to 58 percent black 13 years later.

The district and appeals courts held that, because Norfolk had been adjudged a unitary system, the school board had the right to reinstitute neighborhood schools no matter the racial result and despite the admittedly racial rationale. The courts noted that Norfolk's board is now made up of four whites and three blacks; its superintendent is black; so are two of its three regional assistant superintendents; and its faculty is 56 percent white, 44 percent black. The vote to revert to neighborhood schools (at the elementary level only; secondary students would continue to be bused) was 5 to 2; one of the black members voted with the four whites. How can a court say a system with a makeup and record like that is discriminating against blacks?

Civil rights groups fear the decision will spread if it stands. Its abruptness is part of what disturbs them, the idea that a board can somehow go in a day from having an affirmative duty to desegregate to having no special duty in this regard at all. But if that makes no sense, what does? A time does come when the right thing to do is let a school board off the mat. When and on what terms? The advocates need to help answer those questions.