National Probation Service Polygraph Update
National Probation Service Update
Since August 2015 to end November 2019, National Probation Service has carried out 4,401 examinations on 1,994 sexual offenders using single issue tests. 1,324 tests have resulted in significant disclosures leading to better risk management plans or the offender being returned to custody if they disclose breaches of other licence conditions or information that means they can no longer be safely managed in the community.
Polygraph examinations have been successfully used in the management of sexual offenders since January 2013 in the National Probation Service. The polygraph is used with sexual offenders released on licence. It works by measuring the physiological changes in the body when the individual being tested is asked certain questions. The polygraph instrument measures changes in heart rate, blood pressure, respiratory rate and sweat and the changes to the individual’s normal rates can indicate the subject is attempting to be deceptive.
They are used to monitor compliance with licence conditions and the information obtained during testing is used by offender managers to refine and improve risk management plans. Examinations are carried out by experienced qualified Probation Officers who have been trained as accredited examiners to the standards set by the American Polygraph Association (APA) and who are also experienced in managing high risk offenders.
The APA carried out a meta-analysis of the various polygraph techniques used by polygraph examiners in 2011. This included ‘single issue tests’ that are used in the UK by the National Probation Service examiners testing sexual offenders and would be used with domestic abuse perpetrators. These studies involved 32 different samples and described the results of 45 different experiments and surveys. The results produced a decision accuracy rate of 89%, with an estimated inconclusive rate of 11%. In other words, of the tests under consideration 89% were accurate in terms of reliability and 11% of the tests were inconclusive.
These findings were consistent with a previous study carried out by the National Research Council of the National Academies of Science published in 2003. This provides additional support for the validity of polygraph testing when conducted in accordance with the APA Standards of Practice.
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