This evidence review synthesises the published evaluations and policy documents relating to mandatory post-conviction sex offender polygraph testing (PCSOT) in England and Wales. Primary sources include Gannon et al., The Evaluation of the Mandatory Polygraph Pilot (Ministry of Justice Research Series 14/12, 2012), the peer-reviewed version published as Gannon et al., “An Evaluation of Mandatory Polygraph Testing for Sexual Offenders in the United Kingdom,” Sexual Abuse: A Journal of Research and Treatment, 26(2), 178–203 (2014), the Ministry of Justice Domestic Abuse Bill Factsheet (2020), and the HMPPS Polygraph Examinations Policy Framework (re-issued 8 January 2026). Full citations appear in the Sources list.
TL;DR
- Mandatory polygraph testing for high-risk adult sexual offenders on licence was rolled out nationally across England and Wales on 6 January 2014, following a Midlands pilot that began in April 2009.[1]
- In the pilot evaluation, 76.5% of offenders in the polygraph group made at least one clinically significant disclosure, compared with 51.2% in the comparison group.[2]
- By the time of the 2020 Domestic Abuse Bill factsheet, over 7,000 tests had taken place, with two-thirds resulting in significant disclosures.[3]
- No published UK randomised controlled trial has examined the direct impact of mandatory PCSOT on sexual reoffending, and cost-effectiveness data have not been updated since the 2012 pilot evaluation.[4]
Statutory Basis: The Offender Management Act 2007
The legal foundation for mandatory polygraph testing of sexual offenders in England and Wales is contained in sections 28–30 of the Offender Management Act 2007 (OMA 2007). Section 28 enables a polygraph condition to be inserted in the licence of a person serving a relevant custodial sentence — defined as a life sentence or a fixed-term sentence of 12 months or more — for a relevant sexual offence, provided the person is not aged under 18 on release.[5]
Section 29 sets out the practical requirements of the polygraph condition. The released person must participate in polygraph sessions conducted for two specified purposes: monitoring compliance with other licence conditions, and improving the way the person is managed during release. The individual must attend at times specified by an appropriate officer and comply with the polygraph operator’s instructions.[6]
Section 30 provides an important evidentiary safeguard. Evidence of any statement made by the released person while participating in a polygraph session, or any physiological reactions while being questioned in the course of an examination, may not be used in any proceedings against that person for an offence.[7] This prohibition extends to the pre-test interview, the post-test interview, and the examination itself.[8]
From Pilot to National Rollout
Mandatory polygraph testing for adult sexual offenders began as a pilot in April 2009 across the East and West Midlands probation regions.[9] During the pilot, offender managers in those regions could insert a polygraph testing condition into the licences of offenders released from sentences of 12 months or more for a sexual offence, facilitated under the auspices of the OMA 2007.[10]
The pilot was evaluated by Gannon and colleagues, with findings published first as a Ministry of Justice research report in July 2012 and subsequently in peer-reviewed form in 2014. Following the positive disclosure findings, the Ministry of Justice announced in May 2014 that compulsory polygraph testing would be extended to serious sex offenders across England and Wales, building on the Midlands pilot.[11] National rollout had commenced on 6 January 2014.[3]
The scope of mandatory polygraph testing has since been expanded. The Domestic Abuse Act 2021 amended the OMA 2007 to permit polygraph conditions for offenders convicted of relevant domestic abuse offences. As amended, section 28 also extends to relevant terrorist offences.[12]
What the Evaluations Show: Disclosure Rates
The central finding of the pilot evaluation was a substantial difference in disclosure rates between the polygraph group and a comparison group. In the peer-reviewed analysis, offender managers in the polygraph group reported that 76.5% of their offenders had made at least one clinically significant disclosure (CSD), compared with 51.2% of offenders in the comparison group.[2] The polygraph group also made more total disclosures on average: a mean of 2.60 per offender compared with 1.25 in the comparison group.[13]
Key finding: The majority of disclosures made by sexual offenders in the polygraph group were associated with the polygraph session itself, suggesting the testing process was the primary catalyst for new information.[14]
The MoJ Research Series report further noted that approximately one third of offenders — most notably those assessed as higher in risk — failed their first test with a “Deception Indicated” result.[15]
The programme’s scale grew considerably after rollout. By the time of the 2020 Domestic Abuse Bill factsheet, over 7,000 polygraph tests had been conducted with individuals convicted of sexual offences, and two-thirds of those tests had resulted in significant disclosures.[3]
| Measure | Polygraph group | Comparison group |
|---|---|---|
| Proportion making at least one CSD | 76.5% | 51.2% |
| Mean total disclosures per offender | 2.60 | 1.25 |
| Deception Indicated at first test | Approx. one third | N/A |
Actions Taken After Clinically Significant Disclosures
A clinically significant disclosure is defined as new information that the offender discloses, which leads to a change in how they are managed, supervised, or risk-assessed, or to a change in the treatment intervention that they receive.[16] CSDs were consistently higher in the polygraph group than in the comparison group, and the majority related to changes in circumstance or risk.[17]
Following a CSD, offender managers in the polygraph group were more likely to take supervisory action than those in the comparison group. The actions reported included: increasing supervision or controls (including recall); informing a third party; changing supervision focus; informing a Multi-Agency Public Protection (MAPP) meeting or processes; or issuing a warning to the offender.[18] The peer-reviewed analysis confirmed that polygraph offender managers were more likely to take actions involving increasing supervision, informing a third party, informing MAPPA, changing supervision focus, or issuing a warning.[19]
Cost per additional CSD: The pilot evaluation estimated the cost of each additional clinically significant disclosure associated with the mandatory polygraph at £556.[20]
The Statutory Recall Rule
The interaction between polygraph results and recall to custody is governed by both the statutory framework and HMPPS operational policy. The MoJ Domestic Abuse factsheet is explicit: people on supervision subject to a polygraph testing licence condition cannot be recalled to custody solely on the basis of returning a significant response.[21]
The HMPPS Polygraph Examinations Policy Framework (re-issued 8 January 2026) elaborates on this principle. It states that the result of a polygraph examination cannot be used as the basis of recall. However, the policy draws a critical distinction: information gathered from any part of the polygraph session may be passed on to the police or other relevant agencies where a legal gateway permits, and the police may use that information to conduct further investigations which may result in further charges or recall.[22]
Key distinction: Any disclosures made by the person on probation during the polygraph process that suggest the individual can no longer be safely managed in the community can be used as the basis for recall — even though the polygraph result itself cannot.[23]
Examiners operating within this regime must adhere to relevant professional Standards of Practice, and the evidentiary safeguard in section 30 of the OMA 2007 remains the statutory backstop ensuring that physiological data and session statements are inadmissible in criminal proceedings.[7]
Evidence Gaps and Future Directions
Despite the positive disclosure findings and more than a decade of operational use, several significant evidence gaps remain.
Caveat: The supplied sources do not identify any published UK randomised controlled trial examining the direct impact of mandatory PCSOT on sexual recidivism. The published evaluations measure disclosure rates and supervisory actions, not reoffending outcomes.
First, no published UK study has tested whether mandatory PCSOT reduces sexual reoffending through a randomised controlled trial design. The pilot evaluation measured CSDs and supervisory actions as primary outcomes, not reconviction or reoffending rates.[24]
Second, the cost-effectiveness data available in the public domain are limited to the 2012 pilot finding that each additional CSD cost approximately £556.[20] No publicly available update has recalculated this figure following national rollout and the expansion of testing volumes to over 7,000 tests.[3]
Third, none of the supplied sources identifies any published victim-outcome study examining whether mandatory PCSOT has improved outcomes for victims or potential victims of sexual offending. [VERIFY: whether any UK victim-outcome study on PCSOT has been published outside the supplied sources.]
These gaps are not unusual for a relatively novel supervisory tool, but they suggest that further research — particularly on recidivism and broader cost-benefit analyses — would strengthen the evidence base underpinning the programme.
Timeline
Glossary
- CSD — Clinically Significant Disclosure
- New information disclosed by an offender that leads to a change in how they are managed, supervised, risk-assessed, or treated.
- CQT — Comparison Question Test
- A polygraph testing format that compares physiological responses to relevant questions with responses to comparison (control) questions. Widely used in PCSOT programmes.
- RQ — Relevant Question
- A question in a polygraph examination that directly addresses the issue under investigation, such as compliance with a specific licence condition.
- PCSOT — Post-Conviction Sex Offender Testing
- The use of polygraph testing with individuals convicted of sexual offences, typically during community supervision, to monitor compliance and elicit disclosures.
- OMA 2007 — Offender Management Act 2007
- The UK Act of Parliament (sections 28–30) that provides the statutory basis for mandatory polygraph testing as a licence condition for certain sexual (and, as amended, domestic abuse and terrorist) offenders.
- DAA 2021 — Domestic Abuse Act 2021
- The UK Act of Parliament that, among other provisions, amended the OMA 2007 to extend mandatory polygraph conditions to persons convicted of relevant domestic abuse offences.
- HMPPS — His Majesty’s Prison and Probation Service
- The executive agency of the Ministry of Justice responsible for correctional services in England and Wales, including the administration of mandatory polygraph testing.
- MAPPA — Multi-Agency Public Protection Arrangements
- Statutory arrangements in England and Wales through which the police, probation, and prison services work together to manage the risks posed by violent and sexual offenders living in the community.
- MAPP meeting
- A Multi-Agency Public Protection meeting held under MAPPA at which agencies share information and agree risk-management plans for individuals subject to the arrangements.
- APA — American Polygraph Association
- A US-based professional body for polygraph examiners that publishes standards, accredits training programmes, and certifies individual examiners.
- PLC — Probable-Lie Comparison
- A type of comparison question in polygraph testing designed to provoke a physiological response from truthful examinees, providing a baseline against which relevant-question responses are compared.
- DLC — Directed-Lie Comparison
- A comparison question format in which the examinee is instructed to give a known untruthful answer, generating a deliberate physiological response for comparison purposes.
- EDA — Electrodermal Activity
- A measure of electrical conductance of the skin, which varies with sweat gland activity. It is one of the physiological channels recorded during polygraph examinations.
- ANS — Autonomic Nervous System
- The part of the nervous system that controls involuntary bodily functions such as heart rate, respiration, and perspiration — the physiological responses measured in polygraph testing.
This evidence review is published for informational and educational purposes. It summarises findings from the sources cited and does not constitute legal advice, clinical guidance, or an endorsement of any particular testing methodology. Readers requiring advice on the statutory polygraph regime should consult the relevant HMPPS policy frameworks and legislation directly. The British Polygraph Society has no role in the statutory regime administered by HMPPS.
Sources
- Offender Management Act 2007, sections 28–30. legislation.gov.uk. https://www.legislation.gov.uk/ukpga/2007/21/section/28
- Gannon TA, Wood JL, Pina A, Vasquez E, Fraser I. The Evaluation of the Mandatory Polygraph Pilot. Ministry of Justice Research Series 14/12. London: Ministry of Justice, July 2012. ISBN 978-1-84099-555-8. https://www.gov.uk/government/publications/the-evaluation-of-the-mandatory-polygraph-pilot
- Gannon TA, Wood JL, Pina A, Tyler N, Barnoux MFL, Vasquez EA. An evaluation of mandatory polygraph testing for sexual offenders in the United Kingdom. Sexual Abuse: A Journal of Research and Treatment. 2014;26(2):178–203. doi:10.1177/1079063213486836. https://kar.kent.ac.uk/35131/
- Home Office / Ministry of Justice. Domestic Abuse Bill 2020 Factsheets: Mandatory Polygraph Tests Factsheet. GOV.UK. https://www.gov.uk/government/publications/domestic-abuse-bill-2020-factsheets/mandatory-polygraph-tests-factsheet
- HM Prison and Probation Service. Polygraph Examinations — Instructions for Imposing Licence Conditions for Polygraph on People Convicted of Sexual Offences (PCoSOs), Terrorist and Terrorist Connected Offences: Policy Framework. Re-issue date 8 January 2026. https://assets.publishing.service.gov.uk/media/695e66418ab0677c14afdfd0/polygraph-examinations-pf.pdf
- Ministry of Justice. Compulsory lie detector tests for serious sex offenders (news release). 27 May 2014. https://www.gov.uk/government/news/compulsary-lie-detector-tests-for-serious-sex-offenders