New research in California shows that only a tiny fraction - 3.38 percent - of released sex offenders are convicted of a new sex offense within 10 years of release. The study followed 3,577 prisoners who were released between 1997 and 2007 after serving time for sex offenses.
In an even larger parallel study by California's Sex Offender Management Board, tracking 4,204 paroled sex offenders, only 3.21 percent were convicted of a new sex offense within 5 years of release.
In both studies, almost all of the recidivism came within the first year post-release. Sex offenders were returned to custody for parole violations at a lower rate than other paroled prisoners, despite the fact that they were supervised more intensely. And they were more likely to be rearrested for crimes other than sex offenses.
The findings are consistent with a smaller study two years ago of recidivism by civilly committed Sexually Violent Predators. Of 93 such high-risk offenders released from Atascadero State Hospital without completing treatment, only 4.3 percent reoffended within six years.
The data call into question the dramatically higher recidivism rates cited by state evaluators at Sexually Violent Predator (SVP) civil commitment trials. Those data are based on Canadian research with an actuarial instrument called the Static 99. The Static 99 recidivism base rates are 18 percent after five years and 21.3 percent after 10 years, many times higher than the California data.
The statistical procedure of survival analysis may explain some of this discrepancy, but is unlikely to account for most of it. In survival analysis, an offender who dies or is reimprisoned is removed from the data pool, so that only offenders who are at risk of reoffending are calculated.
Rates of detected recidivism among sex offenders have dropped precipitously in recent years. In a 10-year period, sexual assaults against adolescents age 12-17 dropped by 79 percent; substantiated sexual abuse cases involving children dropped 39 percent in the same period. Possible reasons for the decline include greater public awareness and more severe punishments.
The data are a bit hidden at the California Sex Offender Management Board's website, so I have made them available HERE (5-year study) and HERE (10-year study).