bad science

How the Supreme Court Spread a False Statistic About Sex Offenders

Photo: Drew Angerer/Getty Images

When a false idea gains traction, spreading far and wide, it’s always interesting to try to trace it back to its source to figure out what caused it to catch on in the first place. The New York Times has an utterly fascinating story of this sort today, and it pertains to a common myth about sex offenders: that they have extremely high recidivism rates relative to other types of criminals.

As Adam Liptak explains, in 2003 the Supreme Court issued a decision, Smith v. Doe, written by Anthony Kennedy, upholding Alaska’s sex-offender registry in part based on the claim that sex offenders re-offend at a “frightening and high” rate. That phrase, Liptak writes, “has appeared in more than 100 lower-court opinions, and it has helped justify laws that effectively banish registered sex offenders from many aspects of everyday life.” And it’s based on another decision written by Kennedy: “The rate of recidivism of untreated offenders has been estimated to be as high as 80 percent,” he wrote in 2002’s McKune v. Lile.

Okay, so where did he get that number? “The source of the 80 percent figure was a 1986 article in Psychology Today, a magazine written for a general audience,” writes Liptak. “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.” That number is wildly out of line with serious, rigorous attempts to estimate the recidivism rates of sex offenders, which have “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.” Over a longer time span, the number might creep up — the Department of Justice estimated a recidivism rate of 27 percent over 20 years, for example.

Obviously, some sex offenders re-offend, and every effort should be made to prevent them from doing so. But there’s no evidence they do so at a rate anywhere near 80 percent. As Liptak points out, these ideas have been used to push a lot of harsh laws targeting offenders. But many of these laws, criminologists and psychologists agree, do nothing to make anyone safer, and if anything, increase the odds that sex offenders will commit harmful acts again.

This is a useful reminder of just how many nonscientific factors determine which “scientific” claims catch on and spread. No one wants to argue that sex offenders, a group that is widely feared and reviled for understandable reasons, are less dangerous than most people think. That’s just a very difficult argument to make. It’s difficult to stand up to this sort of false statistic, because the statistic feels so intuitively right and is used for a purpose most people agree with: punishing sex offenders more. If Anthony Kennedy can fall for this sort of pseudoscience, the rest of us probably can, too.

How SCOTUS Spread a False Statistic About Sex Offenders