We hold our physicians to high standards because they make life-or-death decisions. Yet when it comes to drug addiction, their behavior can be disturbing. Their overall rates of substance abuse are roughly on par with the rest of the population, at about 10 percent. For prescription drugs, abuse rates for doctors in several specialties are estimated to be even higher—not surprising given their access to addictive medications.

One doctor, who cared for patients while surreptitiously taking large doses of prescription narcotics, wrote in the Contra Costa Times that “I held patients' lives in my hands when I practiced medicine while high on narcotic drugs for 3½ years. I made errors.” Systematic studies connecting medical errors to drug abuse are hard to do, in part because physicians are skilled at hiding their addiction, yet experts who have culled through case data agree that the danger exists. The inspector general for the U.S. Health and Human Services Department is one of them. Earlier this year he called for mandatory random drug testing for all health care workers with access to drugs.

The idea is a good one. We require such testing of airplane pilots, train conductors, truck drivers and others whose impaired behavior could endanger many lives.

In November, California could become the first state to mandate that crucial level of safety in health care. Voters will consider a ballot initiative that includes a requirement for random drug testing for physicians. The bill may not pass, because it also contains medical malpractice initiatives that face strong opposition. But regardless of what Californians decide, their steps to address drug abuse among health care workers should be emulated across the country.

Expecting health care professionals to police themselves has not worked. One 2010 study published in JAMA surveyed almost 2,000 physicians and found that 17 percent said they personally and directly knew an impaired or incompetent physician in the prior three years—yet only 67 percent of those physicians who knew of a colleague's problems reported that person to a relevant authority.

The new California initiative, if made into law, would require the state medical board to oversee a drug- and alcohol-testing program. Random tests would be carried out by doctors' hospitals. Physicians also would be tested when suspected of substance abuse or after an unexpected patient death or serious injury occurred. In addition, doctors would have to report colleagues to the medical board if they suspected drug or alcohol impairment on the job. If doctors tested positive, their medical licenses would be suspended, pending investigation.

We know testing can work, and it may act as an effective deterrent. Since 2004 at Massachusetts General Hospital, a random drug-testing requirement has been in place for anesthesiology residents. During the six years before the program started, there were four substance abuse incidents (uncovered after suspicious behavior prompted for-cause drug testing). But in the 10 years since testing began, not a single resident has tested positive.

Testing, however, should be just the beginning. The goal is not to punish people but to protect patients and get health care providers into treatment so they can safely get back to work. Positive test results should not have to cost physicians their careers: a positive test should lead to a referral to physician health programs that work with state agencies. Most states have such programs, which monitor participants, evaluate needs and direct them to treatment rather than disciplinary action. A 2008 study published in the BMJ tracked 802 doctors monitored by these programs for five years and found that about 65 percent remained free of substance abuse. Some physicians asked to continue being monitored as a guard against relapse. The one-out-of-three relapse rate makes it clear that a continued-testing program is essential to help catch backsliders.

There should be better efforts to aid troubled health care workers when they need it and stronger checks to rein in unnecessary access to prescription opioids and to track controlled substances. But such actions will not happen overnight, and drug testing is a good start. If we expect our train and truck drivers to be sober when they clock in, we should expect nothing less from those who follow the Hippocratic credo to, above all, do no harm.