READERS OF THIS page may recall Sen. Robert Menendez (D-N.J.) in the context of his utterly unjustified derailing of President Obama’s nomination of a highly qualified foreign service officer to be ambassador to Azerbaijan.

Now Mr. Menendez is holding up Mr. Obama’s nomination of a highly qualified federal judge, Patty Shwartz, to the court of appeals.

As the New York Times reported last week, Judge Shwartz has yet to receive a hearing before the Senate Judiciary Committee because Mr. Menendez is invoking the home-state blackball to which the Senate generally defers. When the Times reported on this mysterious and unusual hold by a Democrat of a nomination by a Democratic president, it noted that Mr. Menendez had been the subject of a 2006 corruption investigation by the New Jersey U.S. Attorney’s Office that was led by James Nobile, Judge Shwartz’s long-time companion. (The probe was closed without any charges being filed.)

After the article appeared on the Times’s front page, Mr. Menendez issued a statement acknowledging that he was blocking the nomination and saying his concern was entirely centered on what he deemed to be Judge Shwartz’s deficiencies in the law. “In my opinion, Judge Shwartz did not adequately demonstrate the breadth of knowledge of constitutional law and pivotal Supreme Court decisions . . . that we should expect from a United States Circuit Court judge,” the senator said in the Jan. 6 statement. Mr. Menendez also complained that Judge Shwartz “misapplied the application of strict scrutiny versus rational basis review to the questions at hand.”

The senator’s assurance that personal pique has nothing to do with his position would be reassuring were his evaluation of Judge Shwartz not so at odds with that of, well, just about everyone else in the world. A unanimous panel of the American Bar Association gave Judge Shwartz its highest rating. New Jersey lawyers who have appeared before her or worked with her in private practice or during her lengthy tenure in the federal prosecutor’s office also lavish praise. Judge Shwartz graduated from the University of Pennsylvania Law School and has served as a magistrate judge on the U.S. District Court for the District of New Jersey for the past nine years.

Mr. Menendez’s office says the senator communicated specific and serious concerns about Judge Shwartz’s qualifications for the appeals court before she was nominated; administration and congressional officials dispute that. But that’s almost beside the point. If Judge Shwartz is as unqualified as Mr. Menendez makes her out to be, there would be no better place to reveal her shortcomings than during a confirmation hearing. Mr. Menendez should remove his block to allow his colleagues and the public to make up their own minds. If he won’t, Sen. Patrick Leahy (D-Vt.), chairman of the Judiciary Committee, should schedule a hearing anyway. The president is entitled to have his nominees fairly, vigorously and openly evaluated and voted on. Mr. Menendez is entitled to vote no, if he’s not too embarrassed to do so.