Former Rep. Bob Barr, running for president as a Libertarian, argues that conservatives who care about judicial nominations should not support John McCain for President because "his jurisprudence is likely to be anything but conservative." According to Barr:

The idea of a "living Constitution" long has been popular on the political left. Conservatives routinely dismiss such result-oriented justice, denouncing "judicial activism" and proclaiming their fidelity to "original intent." However, many Republicans, like Mr. McCain, are just as result-oriented as their Democratic opponents. They only disagree over the result desired. . . .

even if a President McCain were to influence the court, it would not likely be in a genuinely conservative direction. His jurisprudence is not conservative.

For instance, most conservatives believe that the First Amendment safeguards political speech. Mr. McCain does not. . . .

In his May 2008 speech on judges at Wake Forest University, Mr. McCain talked about the importance of "the constitutional restraint on power," but in practice he recognizes no limits on government or executive-branch authority. In fact, if Mr. McCain nominated someone in his own image, the appointee would disagree with not only the doctrine of enumerated powers, which limits the federal government to only those tasks explicitly authorized by the Constitution, but also the Constitution's system of checks and balances, and even its explicit grant of the law-making power to Congress. . . .

It is important to choose judicial nominees carefully. But that is no reason for conservatives to vote for Mr. McCain. He has demonstrated no more interest in "conserving" the Constitution, and its principles of limited government and individual liberty, than has Mr. Obama.

This is a smart tack for Barr to take. Many limited government conservatives are quite disgusted by Republican profligacy and incompetence but nonetheless fear having a President Obama nominate two or more justices to the Supreme Court. Challenging McCain's credentials as a "judicial conservative" is one way to discourage conservative support and diminish conservative fervor for his campaign.

Judicial nominations is one of the few issues with the potential to keep many limited government conservatives in McCain's camp. But Bruce Bartlett is skeptical that "at the end of the day . . . the makeup of the Supreme Court will really be all that different under McCain than under Obama." According to Bartlett:

With Democrats virtually guaranteed to control the Senate by a comfortable margin in the next Congress, McCain would have enormous difficulty getting anyone nearly as conservative as Roberts or Alito onto the Supreme Court.

While McCain could theoretically just keep nominating conservatives until the Senate is finally forced to accept one of them, this approach is unlikely. There isn't an unlimited supply of conservative jurists with the requisite experience to be a viable Supreme Court appointee. And if the confirmation process remains as contentious as it has been in recent years, many of those who are qualified will pass on the opportunity to have their lives torn apart.

More likely, McCain would be forced to appoint moderate justices just to get confirmation. . . .

McCain could help himself by explaining what his strategy will be to find dependable conservatives and get them confirmed. However, he has already repudiated the best hope Republicans had for circumventing Democratic opposition: the so-called nuclear option, which would have forced the Senate to give all federal court nominees an up-or-down vote. McCain basically destroyed any hope of getting a parliamentary ruling on this scheme by putting together the Gang of 14, a bipartisan group of senators that agreed to allow all qualified nominees to have a vote before the full Senate.

Conservatives have to ask themselves whether the man who torpedoed the nuclear option is really likely to fight to the bitter end for the kinds of justices they want to see on the court.

Bartlett suggests that Obama will also be constrained in selecting judicial nominees, but I think he overstates his case here. The likelihood of a GOP filibuster of an Obama Supreme Court nominee is quite small (as it should be). Still, if liberal justices are the next to retire, a President Obama would have difficulty moving the Court much to the left.

Note: Barr's op-ed makes the common mistake of conflating the theory of a "unitary executive" with a theory of robust or unconstrained executive power. The theory of the "unitary executive" concerns the nature of the President's control over the executive branch, but has relatively little to say about the scope of executive authority or the degree to which the executive may act unilaterally.