"His mind was great and powerful, without being of the very first order; his penetration strong, though not so acute as that of a Newton, Bacon, or Locke; and as far as he saw, no judgment was ever sounder. It was slow in operation, being little aided by invention or imagination, but sure in conclusion."

That’s how Thomas Jefferson once described George Washington. And if something similar can someday be said of Harriet Miers’s judgment, it will vindicate her Supreme Court nomination — even if, as I suspect, she ranks below all nine of the current justices in terms of sheer brainpower.

But the biggest problem with the personally admirable Miers is not her apparent lack of off-the-page intellectual brilliance. It is the absence of evidence that she has anything like the great judgment of a George Washington, a John Marshall Harlan, a Lewis Powell, or a Sandra Day O’Connor. Or anything like the writing ability of a Louis Brandeis or a Robert Jackson.

At a time when the justices wield more power than ever before, and when the perversities of the appointment process produce nominees with unknown views and zipped lips, the burden of proof should be on the nominee and the White House to show that Miers at least has a first-rate mind, sound judgment, and strong rhetorical skillsAssurances to conservatives that Miers is a gun-toting, evangelical pro-lifer don’t do the job. Nor do assurances to liberals that she has no alarming paper trial or Y chromosome.

A review of the most important ingredients possessed by a good justice-nominee illustrates both why it is so hard to find consensus choices and why we should be able to agree that Miers seems underqualified — even assuming the need for some compromise in quality for the sake of political viability and diversity.

Brainpower and intellectual curiosity. Most of us do not have the size, speed, or skill to play professional football. And most of us do not have the brainpower to acquire a deep understanding of the extraordinarily complex issues that the Court must decide and of the maze of statutes and precedents that it must interpret. Tom Clark, for example, did fine as Harry Truman’s attorney general. And he was hardly the "dumb son of a bitch" that Truman was to call him after putting him on the Court. But Clark lacked the extraordinary mental equipment to become a very distinguished justice.

To be sure, a dazzling intellect alone does not a good justice make. And once above a fairly high brainpower threshold, diminishing returns argue for giving more weight to other virtues.

Is Harriet Miers above that threshold? Not by much, if at all, the currently available evidence suggests. She did very well in law school — but does not appear to have exhibited a truly exceptional mind. She succeeded as a commercial litigator — but mostly in what The New York Times has called "relatively mundane business deals and contract disputes." She was the first woman to head a big Dallas law firm and the Texas State Bar — but those accomplishments do not put her on a par with, say, Powell or O’Connor. He was a nationally prominent litigator who had steered the Richmond School Board through a tense era of court-ordered desegregation and had headed the American Bar Association. She was third in her class at Stanford Law School, the majority leader of the Arizona Senate, and a trial judge, before becoming an Arizona appellate judge.

Intellectual curiosity? When asked by a senator what authors she liked to read, Miers mentioned John Grisham’s legal thrillers. Escapism is fine. But can anyone, anywhere, cite any specific evidence that Miers has ever grappled with any of the great issues of our time — or of any time? Or that she has ever written or said anything thought-provoking or insightful about any issue of constitutional law or public policy?

Judgment. Great judgment is the most important ingredient of a good justice and the most difficult to discern. In the words of Michael Boudin, chief judge of the U.S. Court of Appeals in Boston, judgment includes an almost instinctive sense of proportion, as in sensing how to fit the punishment to the crime; "an ability to think about multiple factors at the same time [and] to consider remote consequences, always asking the question, ‘What will happen next’; … an ability to gauge in advance the reactions of others to events and arguments; … to separate and prefer the reasoned response to one based on emotion; a willingness to make decisions, and do so based on incomplete data."

Miers is credited by friends with good judgment, and she may indeed have it. But, then again, she may not. Cause for concern is her brief turn as White House deputy chief of staff for policy, the job she held between her service as staff secretary and as White House counsel. By many accounts, her desk was a notorious bottleneck because she was a slow decision maker, was reluctant to delegate, was not a natural political strategist, and could get bogged down in the trivia of process — paper flow and punctuation. These are not promising traits for a would-be justice.

Writing ability. Justices must write (or at least edit their clerks) in a clear and coherent way if lower courts and citizens are to know what the law is, why it makes sense, and how it will apply in future cases. Those who write memorably foster public understanding and approbation of the Court’s rulings. And eloquent dissents can plant the seeds of progress, as did Justice Louis Brandeis’s famous 1928 paean to "the right to be let alone — the most comprehensive of rights and the right most valued by civilized men."

The most conspicuous exemplars of Miers’s writing ability may be her notes telling then-Gov. Bush that he was "the best" and "the greatest" and "cool."

Energy, industry, fair-mindedness. These are important ingredients. By all accounts, Miers has them. So do millions of other Americans, and tens of thousands of other lawyers and judges.

Political acceptability. This bottleneck is tighter than ever before. Most of the otherwise best-qualified nominees are unacceptable to the president — as insufficiently conservative, too old, or lacking friends in the key conservative networks. And most of those acceptable to the president are unacceptable to half or more of the senators — as all-too-conservative, too unpredictable, or too unfriendly with liberal groups.

Diversity. Any collegium of nine will make better-considered decisions if they bring a diverse range of personal and professional backgrounds to the group. The current Court’s greatest weakness may well be that all nine justices are former appellate judges, with very little collective experience as trial judges, prosecutors, criminal-defense lawyers, or big-time litigators — let alone as business people, wrongly accused criminal defendants, victims of crime or corporate misconduct, or strugglers against poverty or other adversity.

Chief Justice John Roberts — a well-born, Harvard-educated, inside-the-Beltway appellate-litigator-turned-appellate-judge — makes the Court even less diverse than before. Harriet Miers — a pioneering woman who worked her way through Southern Methodist University School of Law, who has ample litigation experience, and who once sat on the Dallas City Council — would enhance the diversity of the Court’s collective wisdom. She would also fit the public expectation that the Court should look more like America than does the traditional tableau of nine white men.

With several hundred thousand women lawyers in the country, it would be jarring if the president were to replace O’Connor with a man (unless redeemed by Hispanic heritage). So there was good reason to choose an outstanding woman. But Harriet Miers?

Independence. Miers’s closeness to the president is troubling. She has long been his personal lawyer and is now his White House lawyer. This might not be disqualifying if she were independent-minded and if Bush were a keen judge of his aides’ judgment. But she has often sounded like a sycophant. And Bush’s prediction that she would never depart from his judicial philosophy was unintentionally insulting. Should the Senate help a president with a penchant for making dangerously broad claims of executive power put such a loyalist on the Court?

For all of this, some suggest, Miers just might be a fine justice. Well, sure. But she has a very long way to go to show that she is a good bet.