President Bush"s nomination of Judge Samuel Alito to fill Justice Sandra Day O"Connor"s seat on the Supreme Court has generated a chorus of now-familiar criticisms from Democratic senators, activists, and journalists alike.

"It is sad that the president felt he had to pick a nominee likely to divide America instead of choosing a nominee in the mold of Sandra Day O"Connor, who would unify us," lamented Senator Chuck Schumer.

"Nominated by President Bush to replace moderately conservative Justice Sandra Day O"Connor," read a news release from Nan Aron"s Alliance for Justice, "Third Circuit Judge Samuel Alito has a 15-year record of trying to push the law sharply to the right."

And, the Washington Post"s Charles Lane reported, "On some of the most contentious issues that came before the high court, Alito has been to the right of O"Connor, the centrist swing voter he would replace."

That Alito likely will prove to be more conservative than O"Connor, however, should not be a startling revelation. Certainly since Justice O"Connor"s perceived betrayal of the pro-life movement in 1992's Planned Parenthood v. Casey, conservatives have been disappointed with her jurisprudence and have been itching to replace her with a "true" conservative jurist. Even prior to Casey, a 1992 National Review editorial described Justice O"Connor as "an object lesson in the subtly debilitating impact of affirmative action . . ."

With this history in mind, it should not be surprising that President Bush would nominate someone whom he believes is to the right of O"Connor on the issues that matter most to the conservative base. Were there any doubt, the palace coup that aborted Harriet Miers" nomination confirmed that the base would not settle for anything less than a jurist with demonstrable conservative bona fides ensuring that he or she will not be another O"Connor.

Focusing exclusively on Alito"s place at the table vis a vis O"Connor, however, ignores a much more important question. President Bush"s supporters vehemently believe that he promised to nominate a justice in the mold of Thomas and Antonin Scalia. Many assume that by selecting Alito, Bush has done just that.

But which has he given us? A Thomas? Or a Scalia?

Despite the popular tendency to conflate these two conservative justices, significant differences exist between them -- differences of significance not only to legal academics and Washington wonks, but also of tremendous practical significance to the interest groups tussling over the fate of Alito"s nomination.

Of course Bush has selected a nominee who is hostile to Roe v. Wade (any who doubt that Chief Justice Roberts is equally hostile are fooling themselves). But, does Judge Alito share Justice Thomas" belief that the president"s commander-in-chief powers are virtually unbridled, or does he share Justice Scalia"s opinion that the Bush administration"s treatment of so-called "enemy combatants" is patently unconstitutional? Does Alito believe that his home state of New Jersey could establish itself as the Catholic (or Lutheran, Buddhist, etc.) State of New Jersey without offending the First Amendment? Justice Thomas is of such a mind; Justice Scalia, on the other hand, has never embraced such a radical view of the establishment clause. Would a Justice Alito, if he turns out to be an "originalist," (as Thomas and Scalia describe themselves), apply that philosophy consistently, as Justice Thomas has done, or would he twist its malleable dictates to reach outcomes more palatable to the conservative conscience as, I believe, Scalia has done?

People for the American Way, the Alliance for Justice, and other interest groups do themselves and their supporters a tremendous disservice by ignoring these crucial distinctions in favor of highlighting what should already be obvious to all: Bush chose a "true" conservative. The real question is, "Which kind?"

The proper role of stare decisis, or deference to precedent, is one stark difference between Scalia and Thomas that has already entered the discussion of Alito. While Miers" nomination was pending, conservatives were heard huffing and puffing that they would relish a national discussion of conservative judicial ideology. Charles Krauthammer lamented that Miers" nomination meant that Bush had "ducked a fight on the most important domestic question dividing liberals from conservatives: the principles by which one should read and interpret the Constitution." One would imagine that no topic within that debate would be more important to conservatives than the propriety of Roe v. Wade. But, rather than confront Roe head-on, conservatives are shrinking away from the fight.

Judge Alito"s 1985 application for deputy assistant attorney general explained that he was "particularly proud" of his work on cases in which the Reagan administration argued that "the Constitution does not protect the right to an abortion." Instead of embracing this view and girding for a fight, however, conservatives (including Alito himself) have downplayed it, commenting that he was merely "an advocate seeking a job." In the place of an actual debate on the merits of Alito"s position on Roe, or even an honest acknowledgment of his position, the abortion battle has been fought by proxy. Suddenly, stare decisis has become a household phrase among liberal activists and religious conservatives, alike.

The split between Scalia and Thomas on the appropriate role of stare decisis is perhaps their best-known difference. Scalia frequently reports that Thomas "doesn"t believe in stare decisis, period. . . . [I]f a constitutional line of authority is wrong, he would say let"s get it right. I wouldn"t do that." In the terms of what passes for today"s debate on abortion, then, Alito"s position on the role of stare decisis is crucial. Many legal scholars, even on the left side of the political spectrum, believe Roe was wrong, at least in its reasoning if not its outcome. Nevertheless, as Justices O"Connor, David Souter, and Anthony Kennedy showed us in Casey ("reaffirming the central holding of Roe"), a belief in the importance of stare decisis can go a long way towards protecting the legacy of Roe. Chief Justice Roberts even tossed a bone to Democrats on the Senate Judiciary Committee by admitting that Roe is "settled as a precedent" and "entitled to respect under principles of stare decisis."

Thomas" radicalism on this front is perhaps best demonstrated by his 2004 dissent in Elk Grove Unified School District v. Newdow, the infamous Pledge of Allegiance case. The majority of the Court held that Michael Newdow -- the father who sued over his daughter"s school"s practice of reciting the pledge in class -- lacked standing to challenge the pledge because his ex-wife, not he, was the child"s custodial parent entitled to bring such actions. Thomas disagreed with that assessment. He also went one giant step further, arguing that the First Amendment"s Establishment Clause does not even apply to the states. That this is a radical conclusion in itself is probably obvious (most scholars would also probably call it dubious, at best). What is more striking, though, is that Thomas felt it appropriate to make the argument at all. The majority did not even reach the merits of the case. The portion of Thomas" dissent discussing the First Amendment, therefore, was entirely gratuitous -- a fact that is indicative of his unwillingness to let sleeping dogs lie when it comes to precedent. Furthermore, Thomas" approach undercuts decades of precedent presuming that states are limited in their ability to establish religion. The school district did not even take this radical position, although the amicus brief of Phyllis Schlafly"s Eagle Forum did (always a good indicator of the reasonableness of a position). As troubling as the idea of the Baptist State of Kentucky may be, it is equally troubling to know that Justice Thomas is so cavalier about introducing such an interpretation.

To be sure, stare decisis is not a panacea for all that ills the left. After all, an unwavering respect for precedent would have prevented the Warren Court"s landmark reversal on segregation in Brown v. Board of Education. Similarly, the court"s 2003 ruling in Lawrence v. Texas, holding state anti-sodomy laws unconstitutional, would never have arrived were it not for the readiness of the liberal members of the court to reconsider Bowers v. Hardwick.

Further, stare decisis, because of its vague and amorphous contours is a particularly difficult concept to apply neutrally. The willingness of Justices Kennedy, O"Connor, and Souter (who collectively extolled the virtues of stare decisis in Casey) to revisit Bowers in Lawrence drew the ire of Justice Scalia in his Lawrence dissent. Scalia bluntly accused that the Lawrence decision "has thereby exposed Casey"s extraordinary deference to precedent for the result-oriented expedient that it [was]."

When it comes to stare decisis flip-floppery, however, Scalia is arguably as guilty as those he ridiculed in Lawrence. At a recent Federalist Society Lawyers Division meeting in Houston, Scalia elaborated on his standard explanation of the contrast between him and Thomas on stare decisis. Scalia repeated that Thomas is happy to revisit lines of cases he believes are wrong, no matter how settled the area is. Scalia then asserted that he believes it is best to move on once the battle has been fought and lost. Perhaps remembering the makeup of his audience, though, Scalia then added something to the effect of, "Except when it comes to Casey." Indeed, Scalia has expressed his desire to overturn many legal doctrines with which he disagrees. This willingness, however, is a far cry from Thomas" blank-slate approach to constitutional interpretation.

Given past experience, we should also be particularly wary of any assurances from Alito of his respect for stare decisis. During his confirmation hearing, then-Judge Thomas explained, "Stare decisis provides continuity to our system. It provides predictability, and in our process of case-by-case decision-making, I think it is a very important and critical concept." Of course, Justice Thomas" laughable comment on Roe (contending that he"d never discussed the case with anyone, ever) should have tipped us off that the rest of his testimony needed to be taken with a grain of salt. ." Furthermore, when it comes to stare decisis, perhaps Judge Alito"s relative closeness to Scalia or Thomas will have little effect on the abortion question -- neither Thomas nor Scalia would think twice about overturning Roe. But as Thomas" Newdow dissent displays, stare decisis can protect far more than the right to an abortion. The last decade"s worth of experience with Scalia and Thomas demonstrates that it is vitally important to recognize that Alito might emulate either jurist; the question is, "Which one?"

Thomas and Scalia differ significantly in another area of vital concern to liberals: the scope of federal power. Bucking the Rehnquist Court"s general trend of reincarnating meaningful limits to Congress" power under the Commerce Clause, the court held last June that Congress could criminalize the use of medicinal marijuana even in the face of state laws allowing for its use. Proponents of medicinal marijuana argued in Raich v. Ashcroft that because the marijuana in question was grown, distributed and used all within California, interstate commerce was not sufficiently implicated to justify Congress" interference. Writing for the court, Justice John Paul Stevens held otherwise, concluding, "[C]omprehensive regulatory statutes may be validly applied to local conduct that does not, when viewed in isolation, have a significant impact on interstate commerce. . . ." Although this decision was a blow to liberals who sought to loosen federal restrictions on the use of medicinal marijuana, it was a victory for liberals in that it provided hope that the court"s troubling trend of invalidating federal statutes, such as the Violence Against Woman Act, as invalid under the Commerce Clause had come to an end.

On the other hand, some conservatives were apoplectic about the perceived inconsistency between the court"s recent federalism decisions and Raich. In dissent, Justice Thomas opined, "By holding that Congress may regulate activity that is neither interstate nor commerce under the Interstate Commerce Clause, the court abandons any attempt to enforce the Constitution"s limits on federal power."

Liberals may be relieved that the court (if Thomas is correct) has abandoned its attempt to return to a pre-New Deal construction of the Commerce Clause. Thomas" discontent, however, undoubtedly flowed not solely from the outcome of the case but also from the identity of those justices concurring in the outcome, including Justices Kennedy and Scalia. Both had been reliable votes in the Rehnquist Court"s hallmark federalism cases, and although Kennedy did not write to explain his position in Raich, Scalia did. Scalia"s concurrence, quite simply, is difficult to reconcile with his earlier federalism positions. Scalia works hard to convince us that the two positions are consistent, but Justice Thomas is not convinced . . . nor are many others. As Professor Randy Barnett (the lawyer who argued the states" rights position in Raich) explained, "Justice Scalia appears to put his commitment to majoritarianism over his commitment to originalism."

Such a fickle enthusiasm for the judicial philosophy that conservatives espouse as the only legitimate lodestar of constitutional interpretation is troubling indeed. Liberals may not agree with originalism as a judicial philosophy. Nevertheless, I contend most would prefer the principled application of the wrong philosophy to the results-oriented inconsistency that Scalia"s Raich opinion represents. Where Alito falls on this spectrum is unknown. Indeed, his opinions from the Third Circuit reveal little enthusiasm for originalism at all (although Court of Appeals work generally lends itself less to originalist analysis than it does to struggling to apply Supreme Court precedent). Certainly, Senator Schumer would better serve his constituents by probing Alito"s penchant for consistency than by lamenting Alito"s obvious differences vis a vis O"Connor.

Among all the differences in Thomas and Scalia"s jurisprudence, their differing view on the president"s war powers are the most striking. In Hamdi v. Rumsfeld, the court considered the plight of Yaser Hamdi, an American citizen captured in Afghanistan and held as an "enemy combatant" in a naval brig in Charleston, South Carolina. Hamdi generated four different opinions that ran the gamut in terms of their acceptance of the government"s position that the president possesses the inherent (or, alternatively, the statutorily-granted) power to indefinitely detain any person he classifies as an "enemy combatant."

The controlling opinion, authored by Justice O"Connor, declined to accept the administration"s position that the president possesses "plenary authority to detain" anyone under his commander-in-chief powers granted by Article II of the Constitution. O"Connor also declined to accept the view urged on behalf of Hamdi, i.e., that he must be charged with a crime or else released. Instead, the plurality opinion struck a middle course (as Justice O"Connor is known to do) and concluded that Hamdi"s detention was authorized by Congress" Authorization for Use of Military Force ("AUMF") passed just days after September 11, 2001. The AUMF authorized the president to "use all necessary and appropriate force" against those who perpetrated the September 11 attacks. Consequently, the plurality held that Congress indeed authorized the detention of people in Hamdi"s circumstances. Justices Souter and Ginsburg disagreed with the plurality"s conclusion that the AUMF authorized Hamdi"s detention but agreed with the court"s ultimate decision that Hamdi must at least be given a meaningful opportunity to dispute the evidence supporting his classification as an "enemy combatant."

Unsurprisingly, O"Connor"s plurality opinion (in which Chief Justice Rehnquist and Justices Kennedy and Breyer joined) was attacked from both sides. Alone in arguing that the court should be more deferential to the executive branch, Justice Thomas asserted, "Arguably, Congress could provide for additional procedural protections, but until it does, we have no right to insist upon them." According to Thomas, Hamdi could be indefinitely detained and was not even constitutionally entitled to challenge the factual basis for classifying him as an "enemy combatant." Thomas even noted (in a gratuitous outburst reminiscent of his Establishment Clause rant in Newdow), "[T]he president very well may have inherent authority to detain" citizens like Hamdi, even absent express congressional approval. It is this last notion that is the most troubling. Under this conception of the Constitution, the executive branch could imprison any U.S. citizen based only on the president"s arbitrary decision to classify the him or her as an "enemy combatant" -- a classification that Thomas believes need only be backed up by the president"s say-so.

Justice Thomas" lonely perch as the only member of the court to accept such a radical view of the president"s war powers may have become a bit more crowded with the confirmation of Chief Justice Roberts; only time will tell. Justice Scalia, on the other hand, resides reassuringly far from Thomas on this question. In Hamdi, Scalia dissented from the court"s decision because he believed the court was not protective enough of the rights of alleged "enemy combatants." "Where the government accuses a citizen of waging war against it," Scalia wrote, "our constitutional tradition has been to prosecute him in federal court for treason or some other crime," not lock him away indefinitely without charges or access to counsel. In Scalia"s view, it was not relevant whether the AUMF purported to grant the president the authority to detain Hamdi. According to Scalia, Congress could not do so even if it wished. Without Congress suspending the writ of habeas corpus (as it did during the Civil War and no one contends has been done today), the president must charge detainees like Hamdi with a crime or else release them.

Has Justice Scalia strayed from his originalist ways? Hardly. Scalia"s dissent is peppered with references to eighteenth century sources purporting to support his view that the Constitution was originally understood as precluding the Bush administration"s treatment of Hamdi. Justice Thomas also relies on primary sources of the founding era for his position. Many critics of originalism believe the fact that two jurists, both claiming to channel the understanding of founding era Americans, can reach such divergent conclusions on the same question is evidence of an inherent shortcoming in originalism as a philosophy. Justice Scalia frequently defends originalism as the only way for judges to neutrally interpret the Constitution without injecting their personal views into the decision. Yet, the ability to cherry-pick historical sources reveals that his preferred method is easily susceptible to manipulation, and liberals must be particularly wary of the predispositions of those who seek to wield it.

Given that originalist judges can reach such radically different conclusions on this question of singular importance, it is certainly not enough to accept that Alito is more conservative than O"Connor. Following Miers" nomination, many hypothesized that Bush had selected a confidante to the court in the hopes that she would support even the most extreme actions of the executive branch under the guise of the president"s commander-in-chief powers. Chief Justice Roberts" executive branch pedigree (he spent time in both the White House counsel"s office and various divisions of the Department of Justice) also suggests that Bush may be seeking to pack the court with those who share Justice Thomas" radical view of the pesident"s war powers. Whether Judge Alito falls in this same category is not yet known. But it would be a tragedy to let his confirmation hearings pass without even attempting to find out.

Scalia"s relatively myopic view of the president"s powers as commander-in-chief and comparatively deferential approach to precedent hardly suffice to make him the platonic ideal of a Supreme Court Justice. Nor does Thomas"s consistently niggardly view of the Congress" ability to legislate under the Commerce Clause make him an ideal justice. Facing the fact that George Bush occupies the Oval Office for the time being, however, liberals would be well served to recognize that conservative jurists are not a homogenous bunch, and as Yaser Hamdi can attest, their differences can be crucial.