Prison and Mental Illness

Scott Alexander writes,

What about that graph? It’s very suggestive. You see a sudden drop in the number of people in state mental hospitals. Then you see a corresponding sudden rise in the number of people in prison. It looks like there’s some sort of Law Of Conservation Of Institutionalization. Coincidence?

Yes. Absolutely. It is 100% a coincidence. Studies show that the majority of people let out of institutions during the deinstitutionalization process were not violent and that the rate of violent crime committed by the mentally ill did not change with deinstitutionalization. Even if we take the “15% of inmates are severely mentally ill” factoid at face value, that would mean that the severely mentally ill could explain at most 15%-ish of the big jump in prison population in the 1980s. The big jump in prison population in the 1980s was caused by the drug war and by people Getting Tough On Crime. Stop dragging the mentally ill into this.

Another case of “this one chart” not being a compelling argument. Read the whole post. He is not buying the view that de-institutionalization of the mentally ill caused the prison population to rise.