Even after those disgruntled colonists threw off the yoke of restricted rum, sin taxes became a big part of American policy. Alcohol, tobacco, and gambling are generally subject to such taxes wherever they exist in the United States, and it appears likely that legalized marijuana will move that way as well.

As a response to obesity, the basic logic for sin taxes is clear. Sugary and fatty foods, processed foods, and soda can contribute to obesity, and taxing them will make them more expensive, which should decrease demand for them. Sin taxes also rely on two less obvious logical tenets. Firstly, in the U.S., poor and low-income people are more likely to suffer the worst effects of some unhealthy behaviors, meaning that relatively small increases in the price of unhealthy goods can have outsized health impacts. The second is that while increased prices lower demand for a given good, people will still “sin” enough that the taxes will yield some revenues.

If that’s the logic, does it work in practice? A study on increased alcohol taxes in Illinois concluded that when a tax of 1 cent per serving of beer and 5 cents per serving of spirits was imposed in 2009, the state saw a total monthly decrease of 25 percent in drunk-driving deaths, and a whopping 37 percent among young people, in the two years afterward. While those findings were consistent with the findings of previous studies, the Illinois study found in addition that the decrease in drunk-driving deaths occurred even in heavy drinkers, who economists had long believed to have alcohol demands so inflexible as to be considered immune to taxes.

The evidence in favor of sin taxes on cigarettes is less clear, but still convincing. It is well-known at least that cigarette taxes cut cigarette consumption. Still, there is little data on how such taxes affect deaths from smoking-related diseases like lung cancer. The few studies that do exist show that high enough taxes are correlated with small, but significant, decreases in strokes, heart attacks, and lung cancer.

Alcohol and tobacco sin taxes are popular policies not only because of the health impacts on users, but also because alcohol and tobacco both have significant externalities—environmental, economic, and health consequences for people other than the users. Alcohol abusers, for example, can pose a direct danger to others through drunk driving, reckless behavior, and domestic violence. Secondhand cigarette smoke is carcinogenic in its own right, and an allergen and general nuisance beyond that. So sin taxes aren’t just aimed at saving “sinners,” but also protecting those around them.

But not all sin taxes are created equal. Evidence about the effects of sugar and similar taxes on health is limited, since the taxes are relatively new as a public-health tool, and testing them requires long-term monitoring of complicated and sometimes minor interactions and outcomes. Most of the available evidence comes from Mexico, where a one-peso-per-liter tax on sodas and an 8-percent tax on junk food were both put into effect in 2014. Some have declared the taxes a success on the grounds that they have cut Mexico’s extremely high soda and junk-food consumption sharply.