California’s registry isn’t practical. Amanda Agan, a postdoctoral fellow in economics at Princeton studied sex offender registries at The University of Chicago. She explained her findings to NPR’s On the Media in 2011. She compared multiple studies, across multiple types of registries, including ones like California’s, and found that when the information is public, the pattern of recidivism (which means committing a crime again) was discouraging.
When they were in a public registry there was “a slight increase in how much they recidivated,” although “a slight deterrent effect for first-time offenders. But as the registry size grows, it seems like that recidivism effects swamps the first-time registrant effect. And so, we get kind of an overall increase in sex crimes.” Are you getting this? Sex crimes increased.
Again we find that if the government gets involved in preventive measures they make things worse.