IN “Breaking Bad” a high-school chemistry teacher from Albuquerque, New Mexico, sets up a crystal-meth lab to pay his medical bills. The television series, though entertaining, was unrealistic: meth labs are relatively rare in the American south-west. Although meth-usage rates are reported to be highest in the West, states in the Bible belt have the most meth labs. A survey in 2010 noted that counties containing meth labs tend to be disproportionately poor, white and evangelical. Those same communities also happen to be the ones with stiffest restrictions on the sale of alcohol. When Prohibition ended in 1933, local governments began implementing their own bans on alcohol sales, many of which remain to this day. Fifty-three of Kentucky’s 120 counties have some sort of restriction on the sale of alcohol, while another 31 ban its sale altogether. One question posed by social scientists is whether alcohol is a complement to, or a substitute for, drugs. A new paper by Jose Fernandez, Stephan Gohmann and Joshua Pinkston of the University of Louisville claims the latter, suggesting that lifting the ban on alcohol would lead to a drop in meth use.

The authors argue that local prohibitions lower the price of drugs such as meth relative to alcohol. This is hard to prove, because dry counties share many traits with counties that have meth problems. The authors claim that after controlling for factors including income, poverty, population density and race, legalising the sale of alcohol would result in a 37% drop in meth production in dry counties in Kentucky, or by 25% in the state overall.

Since no one knows exactly how many meth labs there are in America, the paper uses those discovered by the police as a proxy for meth production (see map). They provide further evidence for their argument by noting that lifting the ban on selling alcohol would also reduce the number of emergency-room visits for burns from hot substances and chemicals (amateur meth-producers have a habit of setting themselves alight).

A paper written in 1983, “Bootleggers and Baptists”, noted that support for Prohibition came from two groups with radically different motives: Baptists who abhorred drinking on moral grounds, and opportunists who saw an opportunity to profit from bootlegging. If Congress were to propose reinstating Prohibition, perhaps meth-dealers would join the ranks of supporters.