

If you talk to doctors about malpractice, you come to realize that the root of their objections isn’t financial. Yes, the money matters, and, yes, there are horror stories about $200,000 premiums for malpractice insurance. But most premiums are nowhere near that high.

All told, jury awards, settlements and administrative costs  which, by definition, are similar to the combined cost of insurance  add up to less than $10 billion a year. This equals less than one-half of a percentage point of medical spending. There have been years when malpractice payouts rose sharply, but there have also been years when they did not. Over the last two decades, the amount has increased roughly in line with total medical spending, according to a study in the journal Health Affairs, based on a national database.

This being said, the malpractice system does affect the morale of doctors. It leaves them wondering when they will be publicly accused of doing the very thing they’ve sworn not to do: harm patients. Dr. S. Anthony Wolfe, the chief of plastic surgery at Miami Children’s Hospital, told me he had been to court three times in the last 34 years and won all three times. “But it was a Pyrrhic victory,” he said. He spent weeks in court, enduring “rude, demeaning and endless depositions and badgering.”

You can understand why such experiences would lead doctors to order extra tests and treatments.

Perhaps the best-known study of defensive medicine  by Dr. Mark McClellan, who later ran Medicare in the Bush administration, and Daniel Kessler  compared cardiology treatment in states that had capped malpractice awards in the 1980s and early ’90s with those that didn’t. In the states without caps, stenting and other treatments were more common, but the outcomes were no better.

Later research  into various surgical operations, for instance  has found less of evidence of defensive medicine. But Mr. Chandra points out that this later work (including some of his own) is not as elegant as the cardiology paper. States have not made as many changes to malpractice law in recent years, which makes research tricky. That’s why Mr. Chandra’s estimate of the cost of defensive medicine, up to $60 billion a year, stems largely from the cardiology work.

Obviously, the precise amount of defensive medicine can never be known. Anyone who sets out to find a certain answer will be able to cite one study or another. (One good example of ideology dressed up as economics: the American Medical Association does not adjust for inflation when claiming that malpractice costs are soaring.)

Still, the researchers in the field tend to agree about the scale of the problem  and how much malpractice reform might accomplish.