Over on The Right Coast, Mike Rappaport asks Is the President Entitled to Deference on His Supreme Court Nominees?:

Yes, say many right wing legal commentators. But the question is why? It is sometimes said that the Constitution gives the President the decision of which person to nominate and therefore the Senate should defer to that decision. But that seems mistaken. The Constitution also assigns to the Senate the role of advising and consenting to the nomination. Why does the Senate have to defer as to whether to consent? There is nothing in the Constitution about deference.

Another argument is that if the President does not get deference, there will be long and contentious nomination proceedings. Well, that might be, but so what. There are both benefits and costs to such proceedings, and the benefits include educating the public about the Supreme Court. Moreover, this argument begs the question. The President could avoid contentious proceedings by nominating a more moderate person. Why should the Senate have to defer rather than the President?

It is true that the Constitution assigns the President the first move -- he nominates and the Senate must respond. But that does not require the Senate to defer. It merely means that the Senate's job is to judge the person that the President has nominated and to determine whether that person is fit. But that does not suggest that they must defer to his choice. If they determine that his choice is unfit, then they can and should oppose. To put it differently, that the President nominates makes it difficult for the Senate to oppose that nominee because they would have preferred someone else. But it does not preclude the Senate from opposing the nominee because he or she fails to satisfy standards of fitness that the Senate believes to be applicable.

Finally, there is a significant problem with requiring senatorial deference. It allows the President to select nominees who are strongly disposed towards executive power. Senatorial deference might therefore lead over time to a court that is biased towards the executive. By contrast, requiring the President to compromise with the Senate would lead to a more even handed selection of justices.

And neither should the judiciary adopt a "presumption of constitutionality" by which it defers to the opinion of Congress that its statutes are constitutional. The judiciary, like the President, is a separate branch of government entitled to make its own independent assessment of whether or not an act of Congress is constitutional.

Of course, if Senators reject one nominee, they will then confront a second nominee, who may be no better, and may well be worse, from the perspective of the objecting Senators. They should, and likely always will, take this next move by the President into account when deciding whether to oppose a nominee. Readers who think Republicans should defeat Judge Sotomayor, if they had that power, should ask whether they are likely to be more or less happy with President Obama's subsequent nomination.