Penrose's Law

Penrose's Law[3][4] states that the population size of prisons and psychiatric hospitals are inversely related, although this is generally viewed as something of an oversimplification

That was thought up by from Lionel Penrose in 1939 (he was Roger Penrose's father). And it still seems broadly accurate

During 1960–2004, there was a 74% population-adjusted decrease in mental institution beds and a 52% increase in the prison population. The same period saw a 500% increase in overall crime and a 900% increase in violent crimes, with a concurrent 94% increase in the size of the country's police force. Penrose's law proved remarkably robust in the longitudinal perspective