An Evaluation of Mandatory Polygraph Testing for Sexual Offenders in the United Kingdom

Abstract

This research examined whether a government-initiated pilot project of mandatory polygraph testing would increase the disclosures made by community-supervised sexual offenders in the United Kingdom. The Offender Managers of 332 pilot polygraph sexual offenders and 303 sexual offenders who were receiving usual community supervision were telephoned quarterly, over a 21-month period, to collect information about numbers of clinically relevant disclosures, the seriousness of disclosures made, and actions taken as a result of disclosures. Perceptions of polygraph usefulness were also collected. Offender Managers in the pilot polygraph group—compared to comparison Offender Managers—reported (a) a higher proportion of offenders making at least one disclosure (i.e., 76.5% vs. 51.2% respectively), and (b) that their offenders made more total disclosures overall ( Ms = 2.60 vs. 1.25 respectively). The majority of disclosures made by sexual offenders in the polygraph group were associated with the polygraph session itself. Polygraph Offender Managers reported being more likely to take an action that involved increasing supervision, informing a third party, informing Multi-Agency Public Protection Arrangements (MAPPA), changing supervision focus, or issuing a warning to the offender. However, the relative seriousness of disclosures did not appear to differ across groups. In terms of polygraph test results, one third of offenders (most notably those who were higher in risk) failed their first test with “Deception Indicated.” This outcome—received on a first test—was most likely to elicit clinically relevant disclosures. Offender Managers described the polygraph as aiding supervision strategies. This research and its associated caveats are discussed.