Professor John Pfaff was interviewed for Slate’s The Gist series about mass incarceration.
I think what the best data shows is that in the 80s and early 90s when prisons were relatively low and crime was rising, prison did help rein in that growth. Where we are today—with very high prisons and very low crime—that’s our next incremental person you send to prison—that marginal prisoner—is probably a clearly a net social loss. That’s not as effective now as it was before.