President Bush has endured a lot of carping from conservatives, and not just for his handling of the war in Iraq. But one area where he deserves great credit is in his judicial nominations, which are reshaping the courts much in the way President Reagan's picks did 20 years ago.

The president's mark was on display this week as the U.S. Supreme Court heard arguments involving the assignment of public school students on the basis of race. The two cases before the court both involve plans designed to ensure racial balance at schools in their respective districts.

The Seattle school system runs an open enrollment program for the city's 10 high schools in which ninth-graders may choose which school they wish to attend. However, about half the schools are oversubscribed, meaning more students wish to attend than there are places to accommodate them. Under its plan, the Seattle school district required that race be used in what it called a "tiebreaker" to determine who was admitted to the oversubscribed schools if the racial balance fell outside a certain range.

The Louisville (Ky.) plan, which involved all city and surrounding Jefferson County schools, was implemented by the school board after the district emerged from a 25-year court-ordered desegregation plan. The Louisville plan required all schools to have at least 15 percent and no greater than 50 percent black student enrollment.

The school districts don't deny that they make decisions concerning which students attend which schools based on the color of their skin, but the districts claim this sort of racial classification is constitutional because its aims are to promote integration, not segregation. It is much the same case made by colleges and universities to justify affirmative action programs that give preference in admission to minority students on the basis that such programs increase diversity.

But the new Bush-appointed justices didn't appear to be buying the argument this week. As New York Times veteran reporter Linda Greenhouse noted, "By the time the Supreme Court finished hearing arguments on Monday on the student-assignment plans that two urban school systems use to maintain racial integration, the only question was how far the court would go in ruling such plans unconstitutional."

Greenhouse reported that the court's liberal justices "appeared increasingly and visibly dispirited" as the arguments proceeded. Clearly, the balance on the court has shifted, and no longer will justices be able to make up the law as they go along in order to justify what they consider to be socially desirable ends.

The case has occasioned much gnashing of teeth by editorial writers at the Times, The Washington Post and other liberal outlets, who warn that the Supreme Court will turn back the clock on racial justice if it strikes down these school district plans. But the truth is, such plans turn the Constitution's Equal Protection Clause on its head and make a mockery of the landmark Brown v. Board of Education decision, which struck down race-based student assignments in 1954.

It's impossible to know how the justices will ultimately decide these cases, Linda Greenhouse's prediction notwithstanding. But it is fair to say that the cases will be decided by a new majority made up of justices who will read the Constitution, laws and judicial precedents as they were written, rather than twisting the meaning of words to mean the opposite of what they say in plain English.

President Bush promised no less when he nominated Chief Justice John Roberts and Justice Samuel Alito. But you can bet that the new Democrat-controlled Senate will do its best to assure that the president has no further opportunity to shape the federal courts, especially the Supreme Court should a vacancy develop there. The president may have two more years in office, but his ability to appoint judges will be severely limited by the Democrats. Expect a fight over each and every nominee, no matter how well-qualified. Conservatives had better be there to support the president when that time comes.