In all the denunciations of Sen. Trent Lott's after-the-fact endorsement of Strom Thurmond's 1948 presidential campaign, almost no one is talking about the principle on which Thurmond based his defense of segregation. The principle was states' rights.

And so it's not surprising that many Republicans are eager to shove Lott out of his job before this debate goes too deep. For all their attacks on Lott, most contemporary Republicans are just as committed as Lott is to states' rights doctrines.

This creates a problem. Most Republicans -- to their credit -- now embrace the civil rights laws of the 1960s. These laws, after all, were passed with significant support from such important Republican figures as Senate leader Everett McKinley Dirksen and Rep. Bill McCulloch.

But Dirksen, McCulloch and their allies were standing up for the old Republican tradition that defended the power of national government to promote equal rights. That tradition came under attack in 1964 when Republican nominee Barry Goldwater opposed the Civil Rights Act in the name of states' rights, and also because he thought some of its anti-discrimination provisions violated property rights. As Republican Jack Kemp put it recently in a column: "The GOP went wrong in 1964 when Barry Goldwater, no racist, tragically voted against the Civil Rights Act out of misguided ideological purity." That phrase, "'ideological purity," is both accurate and instructive.

It was Goldwater's campaign, of course, that began the era of the Republican South. Post-Goldwater Republicanism swept in millions of States' Rights Democrats, as Thurmond's supporters called themselves, including an ambitious young Mississippian named Trent Lott. Goldwater carried only six states in 1964: South Carolina, Alabama, Mississippi, Louisiana, Georgia and Arizona. The first four of these had been the only states to vote for Thurmond in 1948. Apropos of some of Lott's comments, the overlap did not occur because Goldwater and Thurmond shared some views on national defense. At issue were civil rights -- and states' rights.

One can now hear Republicans groaning: "But that's ancient history and Lott is a problem because he's letting all our opponents dredge it up."

That sentence is true except for the part about ancient history. While most Republicans now support the old civil rights measures, they continue to cast themselves as the party of states' rights, and proudly so. Republican court appointees, from the Supreme Court on down, are busily fashioning a new jurisprudence that uses states' rights as grounds for overturning progressive national legislation. Already, for example, the courts have used states' rights to limit the reach of federal laws on behalf of the disabled and the environment. Where states' rights don't work to eviscerate national legislation, property rights are called in. Sound familiar?

Until Lott reminded us, here's what we had forgotten: States' rights doctrines were invoked in our history for purposes other than preserving the sanctity of state laws. As Grant McConnell put it in his classic book "Private Power and American Democracy," states' rights provided "the classic defense of the privileges enjoyed by local and other elites."

African Americans in the South are among the best-known victims of states' rights claims, but they were not alone in having to turn to the federal government to seek vindication for their rights. It also took federal power to advance the rights of workers (through the Wagner Act and wages and hours laws), to protect consumers and to guarantee the rights of small investors. Federal law protects the rights of women, the disabled and members of religious minorities.

Yes, it's good that many Republicans have come out against what Lott said. But it's significant that many of his earliest and most forceful critics were neoconservative former Democrats (Charles Krauthammer and William Kristol come to mind) who never shared the old states' rights faith. The first Republican senator to issue an outright call on Lott to quit was Rhode Island's Lincoln Chafee, who, as his first name suggests, speaks from his party's oldest tradition of support for federal power.

But Lott's Republican critics who share his states' rights views on many contemporary matters need to explain why states' rights doctrines that were so wrong as a general proposition in 1948 are right today. If the federal government was right to overturn states' rights in defense of African Americans, why is it wrong now to view states' rights with a degree of suspicion and to continue to see the federal government as a bulwark for individual rights? Even if Lott is hustled off the stage, the question will still haunt his party.