Adam Liptak examines the origin of judicial endorsement of sex-offender registries in his NY Times article – “Dubious Data Belies Supreme Court’s Stance on Repeat Sex Offenders”. The takeaway is that Justice Anthony M. Kennedy’s influential majority opinion in the 2003 case, Smith v. Doe, that “the rate of recidivism of untreated offenders has been estimated to be as high as 80 percent,” is a 1986 article in Psychology Today, a magazine written for a general audience. The article was about a counseling program run by the authors, and they made a statement that could be good for business. “Most untreated sex offenders released from prison go on to commit more offenses — indeed, as many as 80 percent do,” the article said, without evidence or elaboration.

The actual statistics:

“There are many ways to calculate recidivism rates, and they vary depending on a host of distinctions. A 2014 Justice Department report found, for instance, that sex offenders generally have low overall recidivism rates for crimes. But they are more likely to commit additional sex offenses than other criminals.

In the three years after release from prison, 1.3 percent of people convicted of other kinds of crimes were arrested for sex offenses, compared to 5.3 percent of sex offenders. Those findings are broadly consistent with seven reports in various states, which found that people convicted of sex crimes committed new sex offenses at rates of 1.7 percent to 5.7 percent in time periods ranging from three to 10 years.

The Justice Department report said the risk of new sex offenses by convicted sex offenders rises over time, reaching 27 percent over 20 years.”