Stock versus flow
There is no disputing that incarceration for property and violent crimes is of huge importance to America’s prison population, but the standard analysis—including Alexander’s critics—fails to distinguish between the stock and flow of drug crime-related incarceration. In fact, there are two ways of looking at the prison population as it relates to drug crimes:
- How many people experience incarceration as a result of a drug-related crime over a certain time period?
- What proportion of the prison population at a particular moment in time was imprisoned for a drug-related crime?
The answers will differ because the length of sentences varies by the kind of crime committed. As of 2009,
the median incarceration time at state facilities for drug offenses was 14 months, exactly half the time for violent crimes. Those convicted of murder served terms of roughly 10 times greater length.