BY NOW JUST about everyone knows who Rosa Parks is, but how many can name the judge who backed her up in her refusal to vacate her seat on a bus in Montgomery, Ala.? His name was Frank M. Johnson Jr., and quite a few people did know it four decades ago, especially in his native state. He was called by the Ku Klux Klan "the most hated man in Alabama" and by the governor, George C. Wallace, an "integrating, carpetbagging scalawagging, bald-faced liar."

By the time of his death last week at the age of 80, his name was on the federal courthouse in Montgomery, and he held the Presidential Medal of Freedom. But for years he was under the protection of U.S. marshals and was socially ostracized in Alabama because of his court rulings in a long series of civil rights cases, beginning with the matter of Rosa Parks.

In that instance, Mr. Johnson was in the majority on a three-judge panel that invalidated segregation on Montgomery's public transit as a violation of the due process and equal protection clauses of the 14th Amendment. In the years that followed, Judge Johnson was involved in a series of extraordinary decisions and orders that, among other things, allowed the great civil rights march from Selma, Ala., to go forward ("nothing more than a peaceful effort on the part of Negro citizens to exercise a classic constitutional right," he noted), threw out an Alabama law barring blacks and women from jury service, integrated the University of Alabama, mandated public funds for court-appointed attorneys, desegregated the Alabama police and required decent food and medical treatment for state prisoners.

There was a great deal more, much of it contributing to Judge Johnson's reputation for what is today called "judicial activism." When he began doing it, however, it was more in the nature of judicial necessity: Federal judges, including Mr. Johnson, were confronted with the need to deal with some appalling practices and conditions that few political leaders at the time had the courage or wisdom to take on. Frank Johnson had both, to the great benefit of his state and his country.