Today, there is a similar debate over vaping, a popular new practice prohibited or heavily restricted in many countries. Electronic cigarettes, which use heating elements to vaporize liquids usually containing nicotine, were invented in China in the early 2000s by Hon Lik, a chemist looking for a way to satisfy his nicotine addiction without dying of lung cancer as his father had. Nicotine itself is far less harmful to smokers than the other chemicals created during combustion. Heavyweight studies confirm that there are much lower levels of dangerous chemicals in e-cigarette vapor than in smoke and fewer biomarkers of harm in the bodies of vapers than smokers.

Some countries argue that vaping is an effective means of reducing smoking, while others want to see it stamped out altogether, fearing that it could give a new lease on life to the tobacco industry. As with drugs and prostitution, this debate pits prohibition against “harm reduction”: the idea that it is better to regulate harmful habits to make them safer than to ban them in the hope of enforcing abstinence, which results in criminals making them more dangerous.

In both the U.K. and the U.S. the rapid growth in vaping has coincided with rapid reductions in smoking rates, especially among young people. Yet there is a stark contrast between the two countries in how vaping has been treated by public health authorities and, as a result, in its safety for users. 

In Britain, vaping is all about nicotine, not drugs. It is socially acceptable and is confined almost entirely to people who have smoked, even among the young. Less than 1% of vapers are people who have never smoked, and there is little sign of young people taking it up faster than they would have taken up smoking. 

A barrel of beer is destroyed during Prohibition in the U.S. PHOTO: BETTMANN ARCHIVE/GETTY IMAGES

There are now 3.6 million vapers in the U.K. and 5.9 million smokers (some people are in both categories). Many British smokers have switched entirely to vaping, encouraged by the government, whose official position is that vaping is 95% safer than smoking, an assertion now backed by early studies of disease incidence. The organizations that have signed a statement saying that vaping is significantly less harmful than smoking include Public Health England, the Association of Directors of Public Health, the Royal College of Physicians and the Royal Society for Public Health.

There have been no deaths and few if any cases of lung illness directly attributed to vaping in the U.K. A recent study has concluded that vaping is now helping up to 70,000 people stop smoking every year by reaching those who failed to quit smoking by other means. “The British public have voted with their feet and are choosing to use e-cigarettes. This is a positive choice, and we should promote it,” says Prof. Linda Bauld of Cancer Research U.K.

In the U.S., by contrast, vaping has killed at least 33 people, injured about 1,500 and earned the wrath of both the Centers for Disease Control and Prevention (CDC) and President Trump. “Big Vape is intentionally addicting our kids to nicotine, merging with Big Tobacco while disguised as antismoking crusaders, peddling known and unknown chemical harms to the adolescent brain … providing a dangerous new delivery platform for potheads and spreading a deadly lung disease,” writes Katy French Talento, until recently President Trump’s health policy adviser.

Why the different experience? The CDC says that most cases of illness are linked to vaping products laced with THC oil, an ingredient of cannabis, “particularly those obtained off the street or from other informal sources (e.g., friends, family members, illicit dealers).” In addition, many American nicotine e-cigs are much stronger than those allowed in Britain, where there is a 2% limit on nicotine concentrations under the EU’s Tobacco Products Directive. A typical Juul is nearly three times as strong.

In Britain, a manufacturer or importer of e-cigarettes must submit a notification to the authorities six months in advance of a product launch and is subject to strict product-safety regulations, including toxicological testing of the ingredients and emissions, as well as rules ensuring tamper-proof and leakproof packaging. Stimulants, colorings and vitamin additives are tightly regulated. 

Few such regulations exist in the U.S. For many observers, this explains the higher injury rate: “What’s happening in the U.S. is not happening here [in Britain], nor is it happening in any other countries where vaping is common,” says John Britton, director of the U.K. Centre for Tobacco & Alcohol Studies at Nottingham University. 

The U.S. Food and Drug Administration has recently proposed rules for regulating e-cigarettes that would echo the British approach by “reviewing a tobacco product’s components, ingredients, additives, constituents, toxicological profile and health impact, as well as how the product is manufactured, packaged and labeled.”

Some fear that this is too late and that politicians will react to the moral panic over vaping by preferring prohibition instead. Michelle Minton of the Competitive Enterprise Institute says: “A ban on flavors, devices or nicotine levels will have the same effect as every other prohibition. People will turn to illicit dealers or try to do it themselves. And, as we saw with the outbreak of tainted THC, this will result in overdoses, injury and death.”

Of course, neither country has gotten everything right. In Britain, the vaping industry argues that some restrictions prevent lifesaving interventions. Philip Morris International —which has developed heat-not-burn products to compete with the rise of vaping and now promises a “smoke-free future”—would like to insert slips into cigarette packs urging smokers to switch, but the ban on advertising e-cigarettes prevents this. And in both countries independent vaping firms argue that strict regulations act as barriers to entry that favor big firms. Mike Hogan, of the U.S. Smoke-Free Alternatives Trade Association, told Politico, “We may be putting the entire ‘harm reduction henhouse’ in the hands of the fox industry”—by which he means Big Tobacco.

The argument for harm reduction is not one that comes easily to some public-health advocates, because it means promoting behaviors that may still be harmful, just less so than the alternative. Vaping doesn’t have to prove entirely safe for it to save lives, given that it mostly replaces smoking.

In the 1980s the British government took the unpopular decision to encourage the distribution of free needles to heroin addicts so that they would not contract H.I.V. by reusing dirty needles. This condoned a dangerous and illegal activity, but it worked: The incidence of H.I.V. among people who inject drugs is much lower in the U.K. than in other countries that initially rejected this approach, including much of the U.S.

By contrast, the U.S. is gradually accepting the harm reduction argument for cannabis, while Britain remains wedded officially to prohibition and has high death rates from drug use. The argument for legal cannabis holds that prohibition makes cannabis on the market stronger and more dangerous, rewards illegal gangs with bumper profits and spawns violence. As with alcohol, decriminalization allows quality control and crime reduction as well as tax revenue.

A century after the American experiment with Prohibition, neither the U.S. nor the U.K. has fully absorbed the lesson of its failure: that public health and safety are best served when governments treat our harmful habits as problems to regulate, not evils to ban.