Similar legislation exists in Canada.In Kansas v. Hendricks, the US Supreme Court upheld as constitutional a Kansas law, the Sexually Violent Predator Act, under which Hendricks, a pedophile, was found to have a "mental abnormality" defined as a "congenital or acquired condition affecting the emotional or volitional capacity which predisposes the person to commit sexually violent offenses to the degree that such person is a menace to the health and safety of others", which allowed the State to confine Hendricks indefinitely irrespective of whether the State provided any treatment to him. In United States v. Comstock, this type of indefinite confinement was upheld for someone previously convicted on child pornography charges; this time a federal law was involved—the Adam Walsh Child Protection and Safety Act. The Walsh Act does not require a conviction on a sex offense charge, but only that the person be a federal prisoner, and one who "has engaged or attempted to engage in sexually violent conduct or child molestation and who is sexually dangerous to others", and who "would have serious difficulty in refraining from sexually violent conduct or child molestation if released".In the US, offenders with pedophilia are more likely to be recommended for civil commitment than non-pedophilic offenders. About half of committed offenders have a diagnosis of pedophilia. Psychiatrist Michael First writes that, since not all people with a paraphilia have difficulty controlling their behavior, the evaluating clinician must present additional evidence of volitional impairment instead of recommending commitment based on pedophilia alone.
Pedophilia appears to be less common in incest offenders, especially fathers and step-fathers. According to a U.S. study on 2429 adult male sex offenders who were categorized as "pedophiles", only 7% identified themselves as exclusive; indicating that many or most child sexual abusers may fall into the non-exclusive category.Some pedophiles do not molest children. Little is known about this population because most studies of pedophilia use criminal or clinical samples, which may not be representative of pedophiles in general. Researcher Michael Seto suggests that pedophiles who commit child sexual abuse do so because of other anti-social traits in addition to their sexual attraction. He states that pedophiles who are "reflective, sensitive to the feelings of others, averse to risk, abstain from alcohol or drug use, and endorse attitudes and beliefs supportive of norms and the laws" may be unlikely to abuse children. A 2015 study indicates that pedophiles who molested children are neurologically distinct from non-offending pedophiles. The pedophilic molesters had neurological deficits suggestive of disruptions in inhibitory regions of the brain, while non-offending pedophiles had no such deficits.According to Abel, Mittleman, and Becker (1985) and Ward et al. (1995), there are generally large distinctions between the characteristics of pedophilic and non-pedophilic molesters.