THE Supreme Court's landmark 1954 decision ending the legal segregation of schools, Brown v. Board of Education, illustrates both the power and the limits of the nation's highest court in protecting Americans' rights.(The 14th Amendment's "equal protection" clause - the basis of Brown - isn't part of the Bill of Rights, but it can be grouped with the Constitution's first 10 amendments as a foundation stone of American liberty.) The moral force of the unanimous decision cannot be exaggerated. It marked a divide in Americans' thinking about racial justice. Yet the decision by itself achieved little. It still required the civil-rights movement, phalanxes of federal marshals, national media coverage of Bull Connor's dogs, and Congress's enactment of the Civil Rights Act of 1964 and the Voting Rights Act of 1965 before the United States truly turned a corner on civil rights. Moreover, if the Brown court was ahead of its time in some respects, it was running to keep up in others. Desegregation had been going on in the military and other parts of the federal government for a decade, and opinion leaders outside the deep South had turned against segregation. The Brown court was radical and conservative at the same time. This pattern marks the history of the Supreme Court. The court has been at its best in safeguarding liberty when it has boldly advanced rights that are rooted in American experience and on which a national consensus is poised to emerge. The court has run into trouble when it has dug in its heels against the movement of legitimate national forces (the pre-Civil War and early New Deal courts), or has taken positions on divisive issues for which no national compromise is yet evident. If the Supreme Court doesn't exactly "follow the election returns," as some charge, it is an integral part of America's constitutional and thus political system. The justices don't represent the American people's transient desires, but they should reflect the people's durable will. The Supreme Court should do what it has always done best: From its Olympian heights, articulate with clarity and moral authority standards that a freedom loving and fair people are haltingly trying, through opinion and politics, to erect themselves.