In The Case for Forensic Polygraph Testing in Post-Adjudication Sexual Offender Examination and Management, polygraph expert witness Ken Blackstone writes:
Forensic polygraph examination has safeguards which keep its error-rate below 10 per cent. This type of polygraph testing is frequently used in the legal, intelligence and investigative communities. As an example, the popularity of the polygraph in the Federal agencies arena is encouraged by the high caliber of training and supervision provided its examiners. Similar standards and training need to be developed and deployed in the area of post-adjudication assessment and management of sexual offenders.
Utility tests, such as the ones most currently popular in sex offender management programs, actually invite errors (false positives and false negatives). A “false positive” can result in a waste of professional resources and it can unfairly hamper the otherwise honest sex offender who is trying to rebuild his life. A “false negative” can allow recidivism that could have been stopped before anything happened*. Here are some examples where forensic polygraph examination may have helped prevent tragic crimes from occurring:
* Phillip Garrido was a registered sex offender on Federal and State parole for rape when he abducted then 11-year-old Jaycee Dugard and while he held her captive for the next 18 years. He was excluded from required polygraph.
*John Couey was a registered sex offender in Florida and was on state probation when he abducted, raped, and murdered then 9-year-old Jessica Lunsford. His probation supervision failed and he was excluded from polygraph surveillance. Jessica’s body was discovered as a result of a polygraph examination.
Examples such as Garrido and Couey represent statistical outliers; however they underscore the need for a disciplined approach that requires forensic testing methods and standards.
Ken Blackstone is an expert regarding polygraph examinations. He is the author of the book Polygraph, Sex Offenders, and the Court (2011, Emerson Books ISBN 978-061-5506-80-7). www.blackstonepolygraph.com