Gallup's annual poll on confidence in institutions, released June 20, finds "just 12 percent of Americans expressing confidence in Congress, the lowest of the 16 institutions tested this year, and the worst rating Gallup has measured for any institution in the 35-year history of this question." That fraction is down sharply from an already dismal 30 percent as recently as 2004.

And yet we continue to elect and reelect scoundrels, liars, hypocrites and the intellectually challenged. The elusive quality of "electability" seems not to correlate with truthfulness, integrity, courage or intelligence, but only with a certain affability — and with the ability to raise funds for campaigns.

It's no coincidence that the intelligence of members of Congress has so often been spoofed. "Suppose you were an idiot and suppose you were a member of Congress. But I repeat myself," quipped Mark Twain. Milton Berle observed, "You can lead a man to Congress, but you can't make him think." Will Rogers addressed the consequences of these deficiencies: "When Congress makes a joke it's a law, and when they make a law, it's a joke."

There are innumerable examples of the joke being on us. A friend of mine was seated at a banquet table with the family of then-Rep. Dan Glickman, Kansas Democrat. The family expressed relief at his having entered politics because none of them thought Dan was smart enough to enter the family business: auto and appliance shredding and scrap metal.

I was at a symposium that Rep. Tom Bliley, Virginia Republican, then chairman of the powerful House Commerce Committee, attended by teleconference. As he recited from a prepared statement, he included the "stage instructions" — such as "Pause for emphasis" — that had been inserted by his speechwriter. And where one line had been inadvertently duplicated, Mr. Bliley read it a second time. Carelessness? Stupidity? Senility? Don't voters have a right to know?

Sen. Pete Domenici, New Mexico Republican, was forthright enough to reveal last year that he had been diagnosed with frontotemporal lobar degeneration (FTLD) - an inexorably progressive, incurable disease characterized by wasting away of the frontal and temporal lobes of the brain. Because of the behavioral changes and dementia that accompany this condition, Mr. Domenici announced he would not seek re-election this year.

I have great sympathy for Mr. Domenici, who is in the twilight of both career and life. But did the people of New Mexico deserve to be represented for more than another year by a senator who admits to suffering from progressive dementia? I believe he should have resigned at the time his illness was diagnosed.

And then there is nonagenarian Sen. Robert Byrd, West Virginia Democrat, the longest serving senator in American history. In his 51st year in the senate, the 90-year old's public utterances as captured on YouTube speak for themselves. In the first of these clips, Mr. Byrd maunders; in the second, during a 2001 interview on "Fox News Sunday," the remarks of this former recruiter for the Ku Klux Klan are grossly inappropriate. Several times he uses a racial epithet often applied to blacks to describe some white persons.

As a voter and taxpayer, but also as a physician, I worry about whether such people are fit to serve. Nor are they isolated examples. Giving cause for concern are the two U.S. senators who are supposed to represent my own interests are dubious: Democratic Sen. Dianne Feinstein, 74, and Sen. Barbara Boxer of California. Mrs. Boxer usually seems befuddled; and Mrs. Feinstein, a multimillionaire, may look good with her expensive clothes, jewelry, hair-styling and makeup, but flaws in knowledge and judgment make her a liability.

Other states have candidates for legislators who belong not in the House or Senate but in assisted living: Sens. Patrick Leahy, Vermont Democrat, 67; Arlen Specter, Pennsylvania Republican, 77; and Reps. John Dingell, Michigan Democrat, 81; Ralph Hall, Texas Republican, 84; and John Conyers, Michigan Democrat, 78. All are well past their use-by dates.

Perhaps we should treat dissatisfaction with our representation as a medical, rather than a solely political, issue. How? By asking candidates and incumbents to volunteer for periodic intelligence and mental status testing. After all, we often demand to know whether a candidate has recovered from open-heart surgery, cancer or a stroke, and many states require elderly drivers to be relicensed. Isn't control over the nation's coffers and the responsibility for declaring war as important as the ability to drive a car?

A mental status exam by an expert offers an assessment of cognitive abilities, memory and quality of thought processes. It includes assessments of alertness; speech; behavior; awareness of environment; mood; affect; rationality of thought processes; appropriateness of thought content (presence of delusions, hallucinations, or phobias); memory; ability to perform simple calculations; judgment ("If you found a letter on the ground in front of a mailbox, what would you do with it?"); and higher reasoning, such as the ability to interpret proverbs abstractly ("A stitch in time saves nine.").

An intelligence test measures various parameters that are thought to correlate with academic or financial achievement. Every legislator need not be a genius, but I would like mine to be smarter than the average person in the supermarket or laundromat.

The journalist and satirist H.L. Mencken observed, "Congress consists of one-third, more or less, scoundrels; two-thirds, more or less, idiots; and three-thirds, more or less, poltroons." Testing might help us to weed out a few idiots. Getting rid of the scoundrels and poltroons will have to wait.