Ending or significantly reforming the war on drugs has long been cited as a primary way to lower America's record-setting incarceration rate. In recent years, however, the extent of the potential impact of decriminalizing drug use has been challenged, with one study finding that only one in five inmates in state and federal prisons is held on drug charges.
Now, new research from the Brookings Institute finds that measuring the proportion of drug offenders in a snapshot of inmate populations may be misleading. That's because drug sentences tend to be shorter than sentences for more serious crimes like homicide, so murderers wind up being overrepresented in studies which look at the static stock of prisons at a single moment, while drug users are underrepresented.
To better measure the effect of drug laws on incarceration, the Brookings study looks at the flow of inmates in and out of prison over time: