In New Jersey, cutting in half the number of drug convictions would reduce prisons by just 3%

From the New York Times via Marginal Revolution: 

A new interactive “prison population forecaster,” posted online Tuesday by the Urban Institute, a liberal-leaning think tank in Washington, aims to help fill that void and yields some sobering conclusions.

The interactive program allows you to assess for yourself the impact of different policy changes. Cut in half the sentences for those convicted of property crimes? Inmates in 2021 are down by 10 percent....

I was startled by these calculations for New Jersey, for example: Cutting in half the number of people sent to prison for drug crimes would reduce the prison population at the end of 2021 by only 3 percent. By contrast, cutting the effective sentences, or time actually served, for violent offenders by just 15 percent would reduce the number of inmates in 2021 by 7 percent — more than twice as much, but still hardly the revolution many reformers seek.