The mantra that led many conservatives to embrace the issue of criminal justice reform was a statement of common sense. Criminals come in all shapes and sizes, and there is a big difference between the people we are upset with and the people we are afraid of.

In the former group, we might include those guilty of important but still minor nonviolent crimes, such as drug possession. Such people need to be arrested and punished, of course — this isn’t an endorsement of San Francisco’s current lawlessness. But for most such crimes, the effectiveness of a prison sentence has diminishing returns as it grows longer.