[Page 752]The penile plethysmograph (PPG), or p-graph, is an individually applied physiological test that measures the flow of blood to and from the genital area. The p-graph is currently being deployed in hundreds of adult and juvenile sex offender treatment centers in the United States and in several countries around the world. Sex offenders have relatively high rates of reoffending, and in the United States, many state legislatures have responded by passing restrictive legislation, while courts frequently mandate close supervision and surveillance of release of these offenders. In most cases, the clinicians are asked to evaluate individuals accused or convicted of sexual offenses for an assessment of dangerousness, risk for recidivism, involuntary commitment determinations, inclusion in sex offender registry, or criminal responsibility. Since PPG is ...