This research brief draws primarily on Keeton S, Gerasimov W & Pearce L, “The use and operation of counter-terrorism polygraph examinations: Process evaluation findings” (Ministry of Justice Analytical Series, October 2023), one of the few published UK government evaluations to address countermeasures in operational polygraph practice. Full citation at entry 1 of the Sources list.
TL;DR
- Countermeasures are defined as anything a person on probation does in a deliberate effort to defeat or distort a polygraph examination — for example, breath holding or taking medications.[1]
- The Keeton 2023 counter-terrorism (CT) process evaluation provides rare UK field data: 88 polygraph examinations completed by 39 individuals over approximately two years.[2]
- No published UK prevalence study on countermeasure use exists for either the CT or the post-conviction sex offender testing (PCSOT) cohort.
- No published inter-examiner reliability study on countermeasure detection in UK field practice has been identified.
- Closing these gaps would require routine field data collection and cross-examiner reliability audits — neither of which is currently reported in the public domain.
What Are Countermeasures?
The 2023 Ministry of Justice process evaluation of counter-terrorism polygraph examinations provides one of the clearest operational definitions yet published in a UK government document:
“Countermeasures are anything that a person on probation does in a deliberate effort to defeat or distort a polygraph examination, for example breath holding or taking medications.”[1]
The definition is deliberately broad. It encompasses physical manoeuvres (such as controlled breathing patterns or deliberate muscle tension), pharmacological interventions (such as the use of anxiolytics or other medications), and mental strategies (such as cognitive tasks designed to augment or suppress physiological responses to specific questions). Crucially, the definition centres on intent: a countermeasure is a deliberate act, not an involuntary physiological variation or a movement artefact produced without awareness.
Why Countermeasures Matter
The purpose of any comparison-question test (CQT) is to compare physiological responses to relevant questions (RQs) with responses to comparison questions (CQs). If an examinee can artificially inflate responses to CQs or suppress responses to RQs, the resulting pattern may resemble a non-deceptive outcome — even if the examinee is, in fact, being deceptive. Conversely, poorly executed countermeasure attempts can introduce artefacts that render charts unscorable, leading to inconclusive results. In either case, the integrity of the examination is compromised.
In a criminal-justice supervision context — whether Offender Management Act 2007 sex-offender testing or CT polygraph — countermeasures are not merely a methodological nuisance. They have direct implications for public protection, because an examination outcome distorted by countermeasures may fail to elicit risk-relevant disclosures that would otherwise inform supervision decisions.
What UK Field Data Exists
The Keeton 2023 CT Process Evaluation
The Keeton et al. (2023) evaluation is, to date, the most detailed published UK government account of the CT polygraph programme’s operation. Over approximately two years, 88 polygraph examinations were completed by 39 individuals.[2] Thirty-one of those examinations (35%) resulted in a significant-response classification, and disclosures of risk-related information were recorded in 63 instances (72% of examinations).[3]
The evaluation also describes the quality-assurance framework. Polygraph examiners had been trained and accredited to the standards set by the American Polygraph Association (APA). Regular reviews, professional development, cohort-specific training, and refresher training were in place to ensure consistency across CT examiners. All polygraph examination outcomes and reports were quality-assured by an external provider of polygraph services to the Ministry of Justice.[4]
Importantly, while Keeton et al. define countermeasures and acknowledge their relevance, the evaluation does not publish a separate prevalence figure for detected or suspected countermeasure use within the 88-examination dataset.
Grubin 2016: Field Experience in PCSOT
Grubin (2016) provides context for the wider UK polygraph programme. Following trials, mandatory testing of high-risk sex offenders on parole was introduced in England and Wales in 2014 under the Offender Management Act 2007. Probation officers reported that new disclosures relevant to treatment or supervision were made in 70% of first tests, compared with 14% of non-polygraphed offenders making similar disclosures in the preceding six months.[5]
While Grubin discusses field experience and the general methodological landscape, the 2016 paper does not report countermeasure prevalence data from the UK PCSOT cohort.
What UK Field Data Does Not Exist
Evidence Gaps — Stated Plainly
- No published UK prevalence study for countermeasure use in the PCSOT cohort. Although mandatory sex-offender polygraph testing has been operational since 2014, no publicly available study reports the proportion of examinations in which countermeasures were detected or suspected.
- No published UK prevalence study for countermeasure use in the CT cohort. Keeton et al. (2023) define countermeasures and describe quality-assurance arrangements but do not report a separate countermeasure-detection rate from the 88 examinations.[6]
- No published inter-examiner reliability study on countermeasure detection in UK practice. It is not known from publicly available data whether different UK examiners, presented with the same chart data, would agree on the presence or absence of countermeasure artefacts.
These are not criticisms of the existing programmes; they reflect the current state of what has been placed in the public domain. The absence of published data does not necessarily mean data has not been collected internally — only that it has not been published in a form available for independent review.
Implications for Examining Practice
Given the acknowledged threat that countermeasures pose to examination validity, practitioners operating in the UK can draw on several procedural safeguards, many of which are consistent with the APA standards to which UK examiners in both statutory programmes have been accredited:[7]
- Pre-test explanation. Informing the examinee during the pre-test phase that the instrumentation includes movement sensors and that countermeasure attempts are monitored. This serves both a deterrent and an informed-consent function.
- Movement-sensor monitoring. The use of seat and limb sensors alongside standard pneumograph, electrodermal, and cardiovascular channels. Movement artefacts that coincide with specific question presentations may indicate deliberate physical countermeasures.
- Post-test interview on detected artefacts. Where artefacts are observed, a structured post-test discussion provides the examinee with an opportunity to explain anomalous chart activity — and provides the examiner with additional information for the final report.
- External quality assurance. All examination outcomes and reports in the CT programme are quality-assured by an external provider, which offers a secondary review of chart data including potential countermeasure indicators.[8]
Adherence to the Standards of Practice and Code of Ethics that govern professional conduct provides an additional framework for ensuring that countermeasure detection is approached systematically rather than on an ad hoc basis.
What Would Close the Gap
Two categories of evidence would materially strengthen the UK knowledge base on countermeasures:
| Gap | What Is Needed | Why It Matters |
|---|---|---|
| Prevalence data | Routine, anonymised reporting of countermeasure detection rates across both the PCSOT and CT cohorts | Without a baseline rate, it is impossible to assess whether detection protocols are effective or whether countermeasure use is increasing, stable, or declining |
| Inter-examiner reliability | Cross-examiner reliability audits in which multiple qualified examiners independently review the same chart data for countermeasure indicators | Without reliability data, there is no published basis for confidence that countermeasure judgements are consistent across examiners |
Neither type of study would require fundamentally new infrastructure. The CT programme already has an external quality-assurance process in place,[9] and similar arrangements exist for the PCSOT programme. What is needed is the systematic publication of findings derived from that quality-assurance activity, in a form that permits independent scrutiny.
Glossary
- Countermeasure
- Any deliberate action taken by an examinee to defeat or distort a polygraph examination. Examples include controlled breathing, muscle tension, and pharmacological interventions.
- CQT (Comparison Question Test)
- A polygraph testing format that compares physiological responses to relevant questions with responses to comparison questions, in order to assess whether the examinee is being deceptive about the relevant issue.
- RQ (Relevant Question)
- A question in a polygraph examination that directly addresses the issue under investigation — for example, compliance with licence conditions.
- CQ (Comparison Question)
- A question designed to elicit a physiological response in non-deceptive examinees, providing a baseline against which responses to relevant questions are compared.
- PLC (Probable-Lie Comparison)
- A type of comparison question to which the examinee is expected to answer untruthfully (or at least uncertainly), on the assumption that the question addresses a broadly applicable behaviour the examinee is unlikely to deny with complete honesty.
- DLC (Directed-Lie Comparison)
- A type of comparison question in which the examinee is explicitly instructed to answer untruthfully, providing a known-lie baseline for comparison with relevant-question responses.
- Artefact
- An anomalous signal in polygraph chart data that is not attributable to the question stimulus. Artefacts may be caused by movement, coughing, external noise, or deliberate countermeasure activity.
- PCSOT (Post-Conviction Sex Offender Testing)
- The use of polygraph examinations as a supervision tool for convicted sex offenders subject to community management, mandated in England and Wales under the Offender Management Act 2007.
- CT (Counter-Terrorism)
- In this context, the polygraph programme for individuals released on licence following conviction for terrorism-related offences, enabled by the Counter-Terrorism and Sentencing Act 2021.
- APA (American Polygraph Association)
- A United States–based professional organisation that sets standards for polygraph education, training, and practice. UK statutory-programme examiners have been accredited to APA standards.
- EDA (Electrodermal Activity)
- Changes in the electrical conductivity of the skin, driven by sweat-gland activity, measured as one of the standard physiological channels in polygraph testing.
- HMPPS (His Majesty’s Prison and Probation Service)
- The executive agency of the Ministry of Justice responsible for the management of prisons and probation services in England and Wales, including the administration of statutory polygraph programmes.
Sources
- Keeton S, Gerasimov W, Pearce L. The use and operation of counter-terrorism polygraph examinations: Process evaluation findings. Ministry of Justice Analytical Series. October 2023. Available at: assets.publishing.service.gov.uk.
- Grubin D. Polygraph Testing of Sex Offenders. Polygraph. 2016;45(2):97–116. Available at: polygraph.org.
This post is a research brief prepared by the British Polygraph Society for informational purposes. It is not a detection protocol, an operational procedure, or a substitute for professional training. Practitioners should consult the applicable APA standards, their programme-specific guidance, and relevant statutory instruments. Readers seeking further information on UK polygraph legislation may refer to the UK Legal Framework page.