Similar to aspects of Alcoholics Anonymous, relapse prevention has sex offenders own up to wrongdoing and resign themselves to a lifelong day-to-day struggle with temptation. But one of the few authoritative studies of the method, conducted in California from 1985 to 2001, found that those who entered relapse prevention treatment were slightly more likely to offend again than those who got no therapy at all.

Clinicians who work with sex offenders cling to relapse prevention nonetheless, and its durability speaks volumes about the troubled, politically fraught science of treating sex offenders. Not only is relapse prevention of questionable value, but so are the tests to gauge whether sex offenders in treatment still get inappropriately aroused, the drugs used for so-called chemical castration and the methods of predicting risk of reoffending.

• http://www.nytimes.com/2007/03/06/us/06civil.html?ei=5124&en=c1bef6f9b6e947ee&ex=1330923600&exprod=permalink&partner=permalink