From the bench on the final day of this Supreme Court term, Stephen G. Breyer offered a stinging dissent in the case limiting local school board power to adopt racial mixing policies — but the barb also summed up moderate and liberal frustration at the court’s behavior during the preceding nine months. “It’s not often in law,” the justice said, “that so few have changed so much so quickly.”

Breyer was referring directly to the conservative majority of his colleagues, which solidified during the year under Chief Justice John G. Roberts Jr. But his remark applies as much to George W. Bush and his judicial-nomination advisers, who in just 24 months shifted the court markedly to the right because of their choices of Roberts and Samuel A. Alito Jr.

Bush’s success in securing the court’s conservative ideology for the next decade or longer — no matter who succeeds him — seems likely to stand as one of his hallmark second-term accomplishments, all the more remarkable given the historic narrowness of his two elections.

But as president, Bush has consistently acted as though empowered by a popular mandate to remake the federal judiciary to satisfy the conservatives who are his political base. Roberts and Alito were screened to suit them. (His failed choice, Harriet Miers, notably was not.) Both reached the court with less than impressive Senate support: Only two chief justices were confirmed with more “no” votes than the 22 cast against Roberts, and no successful nominee in more than a century has won less support from the opposition party than Alito, who received just four Democrats’ votes.

At his hearings Roberts extolled the virtues of judicial modesty and the benefits of unanimous decisions, and his first term’s results appeared to match those views with more unanimous rulings and fewer 5-4 decisions than in the recent past. But his second term saw the highest share of one-vote decisions in the court’s history — 35 percent, or 24 of the 68 argued cases.

With Roberts and Alito voting the same way on all but five cases in the past year, the court cut a wider swath through established law than happened in the first two terms of the previous three chief justices. Brown v. Board of Education came in 1954, Earl Warren’s first term, but his court’s signature decisions on criminal law, reapportionment and free speech all came in the 1960s. The Warren Burger court never did more than trim those precedents. And the court under William H. Rehnquist did not start its marked turn to the right until its third term.

By contrast, the first full year with Bush’s two justices on the court has upset decades of case law. Its school decision unsettles precedents since the 1960s upholding race-conscious pupil assignment policies to promote racial mixing. Its ruling upholding the federal ban on “partial birth” abortions contradicts a requirement, first laid down in 1973, that any abortion regulation include a health exception for the woman. And it effectively gutted one of the two major provisions in the McCain-Feingold campaign finance law, just four years after the court upheld the statute.

In those cases, Roberts and Alito said they were following precedents even while emasculating them. In two others, they joined majorities to explicitly overturn precedents. One, from the 1960s, had created an excuse for missing deadlines for appeals in “unique circumstances.” The other, from 1911, had prevented manufacturers from dictating minimum retail prices for their products; that ruling will likely mean higher consumer costs.

In other ways, business interests that are another big part of the GOP base fared especially well in the past year. Ruling after ruling limited the legal remedies for workers, consumers, investors or taxpayers against wrongs committed by employers, manufacturers, corporate executives or government contractors. Bush’s faith-based initiative also got a measure of legal immunity with a ruling making it difficult for anyone to challenge the government’s largess to religious groups on grounds of separation of church and state.

This rightward shift is likely to be long-lasting. Roberts is 52, and Alito is 57, so both can be expected to serve two decades or more. Clarence Thomas is 59. Only Antonin Scalia and the swing voter, Anthony M. Kennedy, are older than 70, but both seem in good health and to relish their jobs. And so the justices most likely to leave soon are in the liberal bloc. At 87, John Paul Stevens is inevitably near the end of his tenure. Ruth Bader Ginsburg, a cancer survivor, is 74. David H. Souter is only 67 but has been on the job 17 years, and Thomas Goldstein of the well-regarded SCOTUSBlog speculates that Souter may gladly give up his robes to return to New Hampshire.

Conservatives are eager to capitalize on what Bush has wrought. They want to overturn Roe v. Wade, bar all racial preferences in higher education and limit congressional power vis-? -vis the states. All are ideas without great popular support, and in a legislative forum compromise would be necessary to change course on each. At the Supreme Court, however, counting to five is all it takes to change “so much so quickly.”

Kenneth Jost is the Supreme Court editor for CQ Press.