THE REPORT THAT the state of Virginia sterilized at least 7,500 inmates of its mental institutions between 1924 and 1972 falls more in the category of history than of news. It is sad history that may be difficult to understand, let alone accept, in 1980. But in 1927, sterilization of "mental defectives" was widely regarded as a step forward in their treatment. What is disturbing is that the state of Virginia did not get around to repudiating this discredited doctrine until the 1970s.

These sterilization operations were authorized under a law specifically upheld by the Supreme Court in 1927. The case -- Buck V. Bell -- is one on which generations of lawyers have gone to school. As long as certain procedural requirements -- the appointment of a guardian, a hearing and a right to appeal -- were met, the court said, then potential parents who might transmit "insanity, imbecility, etc." to their children could be sterilized without their consent. The prevailing beliefs of the time were reflected in these words: "It is better for all the world, if instead of waiting to execute degenerate offspring for crime, or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind." Justice Oliver Wendell Holmes wrapped it up for the court's 8-to-1 majority with one of his pungent sentences: "Three generations of imbeciles are enough."

Those words have a harsh ring to them now, but they came from one of the patron saints of modern civil liberties. By sterilizing those mental defectives, or so it was then believed, the state made it possible for them to live their lives outside of institutions. Otherwise, they could have been kept in mental hospitals indefinitely.

That view of how best to handle the mentally retarded and the socially misfit was abandoned long ago. But the state of Virginia, in its usual way, was slow to recognize that time and knowledge had passed its sterilization program by. As a result, not until 1972 -- long after eugenics had been discredited elsewhere -- did this program come to an end.

Members of the Virginia General Assembly are, quite properly, rushing around this week trying to modernize their sterilization law. But in addition to doing that and announcing how horrified they are at the history they did not know, they should give some thought to how many other potential horror stories are lying around in old laws and policies that are rarely reviewed or altered. Reverence for the past can be, and often is in Virginia, overdone.

There is a poignant footnote. Those Bucks mentioned in Saturday's news stories are the third generation Justice Holmes wrote about 53 years ago. One of them, Doris, never knew until last summer that she had been sterilized when she was 16. On present-day medical judgment, she is not mentally retarded.