"Many conservatives oppose Judge [Sonia] Sotomayor’s nomination because she does not appear to support originalism…. But when it comes to the race cases before the Supreme Court, too many conservatives abandon both originalism and judicial restraint [by claiming] that the Constitution’s 14th Amendment mandated a policy of strict colorblindness by state and local governments…. The historical evidence that it did is weak…. To seek to invalidate laws without a strong argument that the Constitution requires doing so is precisely what conservatives usually mean by ‘judicial activism.’"

These words — which echo criticism of the Supreme Court’s conservatives by liberal scholars and Democratic senators — packed an extra wallop because they came from a leading conservative commentator, Ramesh Ponnuru of National Review.

His June 23 New York Times op-ed clashed with efforts by other conservatives to depict Sotomayor as a liberal activist and themselves as the champions of judicial restraint, provoking a lively exchange among legal experts on National Review Online.

Some reproached Ponnuru for what Roger Clegg of the Center for Equal Opportunity called "an ill-timed, ill-argued" piece implying that white people do not have the same rights as blacks to the equal protection of the laws. Wendy Long of the conservative Judicial Confirmation Network wondered whether Ponnuru had been "taken hostage by some NYT editorial page terrorists who waterboarded him until he agreed to sign that op-ed piece."

Other conservatives, however, concurred in whole or in part with Ponnuru’s view that racial preferences are not barred by the Constitution even though "unwise and immoral" as a policy matter. And Ponnuru was far from the first prominent conservative to echo liberal claims that the conservative justices are guilty of judicial activism.

By this the critics mean the same kind of usurpation of the elected branches’ powers that conservatives have long attributed to liberals: invoking far-fetched or highly debatable interpretations of the Constitution to impose the unelected justices’ personal political views on the nation. The focus of this debate in recent years has been on conservative efforts to strike down gun control laws, campaign finance regulations and racial affirmative action preferences.

Consider a leading conservative judge’s panning of the 5-4 decision in June 2008 striking down a strict District of Columbia gun control law, when the majority held for the first time that the hopelessly ambiguous, two-century-old Second Amendment protected a broad individual right to "keep and bear arms."

The judge, J. Harvie Wilkinson III, of the U.S. Court of Appeals for the 4th Circuit, argued in a University of Virginia Law Review article that the court’s conservatives had descended almost as far into a "game of dueling activist Constitutions" as did liberals in Roe v. Wade.

Like Roe, wrote Wilkinson, the gun decision "represents an act of judicial aggrandizement: a transfer of power to judges from the political branches of government — and thus, ultimately, from the people themselves." This, he added, could not be justified because the majority’s interpretation was no more persuasive than the four dissenters’ claim that the Second Amendment was intended to protect only the keeping of arms for service in a state militia. "The tie," said Wilkinson, "should go to the side of deference to the democratic process."

Another conservative-leaning jurist went even further, asserting that liberals had been right about the Second Amendment. Writing in The New Republic, Judge Richard Posner of the Court of Appeals for the Seventh Circuit whacked the "faux originalism" of Justice Antonin Scalia’s majority opinion in the gun case as amounting to "a freewheeling discretion strongly flavored with ideology."

It’s possible, of course, that Scalia was right and Wilkinson and Posner were wrong. But such fierce disagreements among conservative legal luminaries dramatize the central problem of constitutional interpretation in today’s world: What justification is there for unelected, life-tenured justices to strike down democratic choices based on highly debatable interpretations of ambiguously worded, indeterminate constitutional provisions?

Consider also the conservative justices’ efforts to strike down or emasculate major provisions of the 2002 McCain-Feingold campaign finance law. Many court-watchers think that they are poised to rule in a pending case, for the first time in history, that the First Amendment guarantees to corporations (as well as to individuals and ideological groups) a right to spend unlimited amounts on broadcast ads supporting or opposing federal candidates.

Such a decision would invite an avalanche of more-than-plausible charges of conservative judicial activism. In part for this reason, I hope to see a statesmanlike compromise emerge, as detailed in my July 11 column.

The judicial activism debate is especially hot in race cases, which in my view will produce the court’s most important decisions in the coming years — together with the national-security cases that conservatives see as a fount of activist encroachments on the powers of the president and Congress.

Countering Ponnuru’s apostasy, Clegg and some other conservative scholars say the 14th Amendment guarantee of "equal protection of the laws" clearly contains no exception for racial discrimination "of a politically correct variety." Thus, wrote Clegg in National Review Online, governmental use of affirmative action preferences in employment and college admissions is as unconstitutional as discriminating against blacks.

Others were more equivocal: "The historical evidence that the 14th Amendment mandated colorblindness is not as weak as Ramesh believes it is," wrote Andrew McCarthy, of the Foundation for Defense of Democracies. "To be sure, it is not overwhelming nor does it disprove all contrary claims, but I do think it is adequate to support a credible originalist rationale for colorblindness."

McCarthy added a more general cautionary note: "Judges… are notorious for creating (or ‘discovering’) new constitutional rights as necessary to advance the leftist agenda. Why not a little substantive due process for our side, too? Except, the point is that we don’t want politically insulated judges imposing any agendas. We just want them to interpret the law as it exists. If our law is out of sync with our preferences… there’s a legitimate way to remedy the problem: Win the public debate and pass a law."

Meanwhile, liberal scholars including Doug Kendall, president of the Constitutional Accountability Center, stress the evidence that the drafters explicitly vested the power to enforce the 14th and 15th Amendments in Congress, not the Supreme Court, which had helped bring on the Civil War by holding, in the infamous 1857 Dred Scott decision, that black Americans were inferior beings with no rights.

Today’s conservative justices have done nothing that approaches the audacity of Roe v. Wade — let alone Dred Scott — as judicial legislation. And there have been signs that Chief Justice John Roberts may be seeking to steer his colleagues toward judicious compromises and constructive dialogue with Congress on issues such as the constitutionality of a key Voting Rights Act provision. (See my June 27 column.)

But it’s fair to fault as activist Justices Scalia, Clarence Thomas and other conservatives who seek to override democratic choices by pressing aggressive interpretations of highly debatable constitutional provisions.

It’s also fair to fault liberal critics of conservative judicial activism for unprincipled selectivity in their respect for precedent. Liberals see the fact that Roe has been on the books for 36 years and repeatedly reaffirmed as a strong argument against overruling it. I agree. But doesn’t the same logic apply to the succession of major precedents over the past three decades ruling that governmental racial preferences and racial gerrymandering are constitutionally suspect?

For that matter, how many of today’s liberals acknowledge — as almost all constitutional scholars did initially — that Roe is made-up constitutional law that can be maintained only on the basis of respect for precedent?

Indeed, the debate among conservatives can be seen not only as showing that judicial activism infects the right, but also as evincing a healthy candor and intellectual vitality that is not always apparent on the left.