Studies of polygraph validity using the control question procedure indicate an accuracy of over 90 percent and a reliability of about 85 percent. Polygraphs have been used in parole/probation decisionmaking and to monitor probationers' compliance with the conditions of their release. Early surveillance programs using polygraph monitoring of sex offenders and highly recidivistic felons were conducted in 1970 and 1973. Initial results suggested that the technique was an effective deterrent. A later controlled study confirmed these results, showing that substance abuse, burglary, and sex offenders in a polygraph supervision plus probation condition had greatly reduced recidivism relative to a probation only control condition. Further, polygraph accuracy did not decrease with repeated testings. For highly compulsive and recidivistic sex offenders, such as pedophiles, polygraph surveillance can help reduce prison overcrowding and related costs, detect reoffending, reduce time spent on probation supervision, aid in protecting society, serve as a deterrent, and assist in rehabilitative treatment. 33 footnotes.