Rather suddenly, the United States Supreme Court switched from generally liberal to generally conservative. In a series of 5-4 decisions, the court voided two school district plans to preserve or achieve racial integration, upheld a federal anti-abortion law, cut back public school students’ rights of free speech, and placed tight new restrictions on bringing and appealing cases.

Why has this happened? The immediate cause is the appointment of Justice Samuel Alito and Chief Justice John Roberts. With Justices Antonin Scalia and Clarence Thomas and with the usually reliable swing vote of Justice Anthony M. Kennedy, a solid 5-vote conservative majority has prevailed.

No one should be surprised. When George W. Bush ran for president in 2000, he said Justices Scalia and Thomas were his ideals as models for Supreme Court nominations. When he was elected in a close vote that ultimately was decided by the Supreme Court, the die was cast. The decision was reinforced when he was reelected in 2004. Conservative nominations were inevitable, and the Senate confirmed them, obeying the widely held belief that judicial qualifications, not likely votes on specific issues, should determine Senate approval. In short, the people got what they voted for, just as they usually have done.

There can be a long time lag, however, in how changes in the court follow elections. Overwhelming support for President Roosevelt blamed “nine old men” for junking key elements of his New Deal to cope with the Great Depression. Later, a liberal court headed by Chief Justice Earl Warren ordered racial desegregation of public schools in Brown v. Board of Education. In 1973, a liberal Supreme Court in Roe v. Wade assured women the right to have abortions.

With the Reagan administration and again in the George W. Bush administration, conservatives have gained increasing strength in demanding reversals of these and other long-standing liberal achievements. Political organization from grass roots up has brought political victories. And the Federalist Society has groomed a generation of skilled conservative lawyers and eventually judges.

The new Supreme Court majority led by Chief Justice Roberts is lessening what had long been considered bedrock social and political rights. The changes sometimes are falling short of outright overthrowing of judicial precedents and rely instead on systematic chipping away. Justice Scalia finds the changes too gradual and has publicly criticized the chief justice for his respect for precedent.

The 2008 election can, in time, determine whether the highest court continues its conservative drive or whether it returns to its earlier mostly liberal or moderate path. Voters should keep in mind that their ballots can control the future direction of the court, not only which nominee they think can lead the way toward a better national health system, a workable approach to global warning, and an end to the seemingly endless Iraq war.