• The seminal event in criminology was the 1972 study by Marvin Wolfgang of the University of Pennsylvania that indicated just 7 percent in the cohort he studied committed more than two-thirds of violent crimes.
For each offense for which they were caught, these chronic offenders committed eight to 11 other crimes. They were rarely punished. Had these “Dirty 7 Percenters” been sent to prison for just a year after their third offense, there’d have been 7,200 fewer serious crimes in Philadelphia, Mr. Wolfgang calculated. Subsequent research here and in Europe has confirmed his findings.
The rate of violent crime has fallen by nearly half since publication of Mr. Wolfgang’s study, chiefly because more chronic offenders are being sent to prison for longer periods. It would have fallen further, but liberals fought against longer sentences. Jack Kelly