Book excerpt: The 109th Congress passed legislation that allows the federal government to civilly commit "sexually dangerous persons". Civil commitment, as it relates to sex offenders, is when a state retains custody of an individual, found by a judge or jury to be a "sexually dangerous person" by involuntarily committing the person to a secure mental health facility after the offender's prison sentence is done. In 1990, the state of Washington passed the first civil commitment law for sexually dangerous persons. Currently, 18 other states and the federal government have similar laws. Moreover, the Supreme Court, in Kansas v. Hendricks and Kansas v. Crane, ruled that current civil commitment laws are constitutional. The civil commitment of sex offenders centres on the belief that sex offenders are more likely than other offenders to re-offend. However, data on sex offender recidivism is varied. Data show that the recidivism risk for sex offenders may be lower than it is typically thought to be; in fact, some studies show that sex offenders recidivate at a lower rate than many other criminals. Other studies show that, given time, almost all sex offenders will commit a new sex crime. Most discussions about recidivism examine ways to decrease it; for example, by providing sex offenders with treatment. Research on the efficacy of sex offender treatment is promising, but it cannot prove that treatment reduces recidivism.