HOWARD ATWOOD KELLY,  ONE OF THE “BIG FOUR” PHYSICIANS who founded Johns Hopkins Hospital in Baltimore, held a view of alcohol typical of his generation. He began his career prescribing it to treat weakness, fevers and other conditions. But he found that “the effect is temporary, evanescent, that the drug (for such it is) does no real good,” he said in 1909. Worse, some patients were incapable of moderation and “a dangerous habit is thus easily engendered.”

That dangerous habit—alcoholism—had come into focus as a problem of its own for physicians to solve in the eighteenth century. For most of history, it had been considered a moral issue, the purview of priests and the police. Then in 1876, the first journal devoted to addiction, the Quarterly Journal of Inebriety, appeared. Its contributors largely promoted a disease model for alcoholism, which looked to environmental and genetic factors as causes, and tried to find evidence-based cures. The editor of QJI for 38 years was T.D. Crothers, author of the first textbooks on alcoholism and a director of two of the most famous U.S. “inebriate asylums”— a new breed of institution that locked up problem drinkers and experimented with diet, baths and exercise for their rehabilitation.

Despite such efforts, rates of alcoholism soared during the first decades of the 20th century. Although Crothers personally believed there was “no rational defense of [alcohol’s] usefulness to civilization,” he insisted that the journal not take sides in the heated, wider cultural debate about a proposed solution—the movement to outlaw the sale of intoxicating liquors altogether.

The political forces gunning for temperance were gaining ground, however, and in the late teens, more and more physicians joined them. The American Medical Association narrowly passed a resolution in 1917 opposing the use of alcohol as a beverage and discouraging doctors from prescribing it as a therapeutic agent—calling it “detrimental to the human economy.” Alcohol use was considered to be responsible for most cases of cirrhosis and, according to 1910 census data, alcoholics accounted for about a tenth of all inmates in mental asylums.

On January 16, 1919, the 36th state approved passing the 18th Amendment, which led to a ban on the manufacture and sale of alcohol beginning in 1920. Forty-seven of the then 48 states eventually ratified the amendment, which many people saw as an end to the nation’s gravest health scourge.

Despite modern views of Prohibition as a quixotic failure, the ban on alcohol had some upsides. A 2006 review published in the American Journal of Public Health argued that Prohibition was “partly successful,” citing an estimated decline of as much as 20% in deaths caused by cirrhosis of the liver. By the 1930s, the average American drank less than a third as much alcohol as before Prohibition. It would take another 35 years after it ended for per capita consumption to rise to pre-Prohibition levels.

Yet for physicians, Prohibition did not stop the debate. The legislation banned liquor as a beverage, but “medicinal use” was still legal, which put them in a curious position. Within six months, more than 15,000 doctors and 75,000 druggists applied for licenses to prescribe alcohol. In Chicago alone, some 500,000 prescriptions for alcohol were issued, though a later analysis suggests that at least 60% of those prescriptions met no good medical need.

Doctors became active in many of the efforts to continue prescribing alcohol and to end Prohibition, even in the first years after it was enacted. The American Medical Editors’ Association argued that the law interfered with the “free practice of therapeutics,” and in 1921, John Davin, a physician activist in New York, went before the U.S. Senate Judiciary Committee to argue in favor of the medicinal qualities of beer. He cited its use as a treatment for anthrax poisoning and anemia.

“How many such lives have you saved?” one senator asked him.

Davin replied, “I should say hundreds.”

“How many hundreds, about?”

“Well, to be modest, say 100.”

In 1922, just two years into the ban, the American Medical Association backed off from its resolution of 1917 condemning alcohol consumption. Some physicians considered any legal ban on alcohol use as an infringement of personal liberty, while others began to suspect that a prohibition on alcohol might actually harm patients. One study in 1928 showed a precipitous drop-off in alcohol consumption in 1920, and another revealed that alcohol-related harm decreased by as much as 60%. But, as observance of the ban faltered, alcohol consumption grew year by year.

In hindsight, Prohibition was a textbook case of unintended consequences. By pushing alcohol production to the black market, it encouraged suppliers to make lower-volume, higher-proof contraband, and the potency of alcohol increased 150%. With increased potency came increases in injury and mortality. Thousands of people died drinking unregulated distilled spirits and adulterated liquor. Medical examiners also discovered that federal authorities had intentionally poisoned industrial alcohol, in an effort to keep it from being diverted for human consumption, but the tactic backfired and killed as many as 10,000 people. And of course, criminal enterprises built on bootleg liquor took countless lives. An accumulation of these factors led, in 1933, to the 21st Amendment, which put an end to the experiment.

Concerns about alcohol use and dependence outlived Prohibition, of course, and efforts to address alcoholism and other addictions continue today. According to Sarah Wakeman, medical director of the Substance Use Disorders Initiative at Massachusetts General Hospital, the unintended consequences of “prohibitionist thinking” continue to dog policies around addictive substances, often harming people who use drugs. Recent efforts to curtail the supply of prescription opioids and heroin, for instance, have created a market filled with ever-more potent substances, including illicitly manufactured fentanyl. These pose an increased risk and cause tens of thousands of deaths, Wakeman says, echoing what happened with bootleg liquor.

“Even though it’s popular to say the opioid crisis is a public health issue, many people—including people in the medical field—think in their heart of hearts that it’s an issue of people behaving badly, who deserve punishment,” Wakeman says. This can translate into policies and practices, both nationally and within hospital systems themselves, that deny medication and treatment to patients who struggle with addiction.

Such attitudes help explain why, of the estimated 21 million Americans with alcohol or substance use disorders, according to the most recent federal survey data, only 19% receive any treatment. “For the past 100 years, we have approached drug use and addiction as a criminal justice issue, not as a medical issue,” says Wakeman. “It’s time for that to change.”