The theory: people are committing fewer crimes because they’re drinking less alcohol

The case for: The correlation is there: Alcohol consumption per capita has been declining since 1977, and hit particularly low levels during the 1990s and 2000s. (It’s gone up slightly since then.) And alcohol abuse is definitely correlated with crime: According to one estimate, 40 percent of violent criminals in state prison were under the influence of alcohol when they committed their crimes.

The case against: Social scientists typically use beer consumption as a proxy for alcohol consumption generally. But while beer consumption has kept declining through the late 2000s, wine and liquor consumption has increased. So the existing research might be getting less useful at measuring how much alcohol people are consuming, which could skew analyses of its effect on crime.

The bottom line: Some effect. A 2015 Brennan Center analysis, as well as past research, shows that there’s a strong association between alcohol consumption and crime. But in the specific case of the crime decline of the 1990s and 2000s, alcohol use simply didn’t decline enough to explain that much of the drop. In all, the Brennan Center estimates, less alcohol consumption explains a small portion of the drop in crime in both the 1990s and the 2000s.