Lie Detector Test UK: Frequently Asked Questions

A typical private specific-issue examination normally addresses one clearly defined issue through no more than three carefully formulated relevant questions. However, the number is not informative by itself. The more important consideration is the type, scope and relationship of the proposed questions.

Three relevant questions do not mean three unrelated topics. One or two questions may be sufficient in some cases. The relevant questions may also be repeated across recordings as part of the examination format. Specialist services may use different structures.

Read more: Why the type and scope of polygraph questions matter more than the number.

Questions usually need to concern defined conduct rather than broad character, feelings or speculation. Suitable questions often use clear behavioural wording, such as whether a person removed, entered, contacted, sent, transferred, accessed, deleted, touched or disclosed something during a defined period.

A suitable question normally has an agreed meaning, a clear time frame, a specific person, item, account, place or event, one clear proposition and an answer that can be understood as yes or no. See the professional question-formulation guidance.

You can suggest questions and explain the concern in your own words. That can be helpful because it shows what you believe is disputed.

Final wording is not simply copied from a client list. The examiner must decide whether the issue is suitable, whether the wording is fair and interpretable, and whether the proposed questions can be used responsibly.

The examinee should understand the relevant questions before testing. The questions are reviewed, discussed and clarified before physiological recording begins.

A professional examination should not depend on surprise. The issue is whether the examinee produces interpretable response patterns to structured, understood questions.

Only if the allegations form one coherent issue and can be reduced to suitable relevant questions. Separate allegations usually require separate scoping and may require separate examinations.

For example, a missing-money matter may involve whether money was removed, transferred or concealed during a defined period. That may still be one issue. By contrast, missing money, suspected sexual contact and phone misuse are not made into one issue just because they are all concerning to the same client.

Questions are commonly unsuitable when they ask about feelings, future behaviour, vague intentions, broad knowledge, legal conclusions, moral labels, whole-lifetime conduct, whole-relationship conduct or several issues at once.

Examples include: “Do you still love them?”, “Will you ever cheat again?”, “Are you a bad person?”, “Have you ever lied to me?” or “Did you steal the money and contact that person and delete the messages?”

Questions about recognition or knowledge may sometimes belong to a different specialist procedure, such as a concealed information test, rather than a standard private specific-issue polygraph examination.

No. A polygraph examination cannot read thoughts, motives, beliefs or private emotional states. It must be anchored to defined behaviour, a defined event or a defined factual proposition that can be answered clearly.

No. A polygraph examination cannot guarantee what a person will or will not do in the future. It may sometimes address past conduct within a defined period, but it cannot certify future honesty or future fidelity.

No. Feelings, attraction, attachment and emotional significance are not normally suitable targets for a specific-issue polygraph examination. If a relationship concern can be examined at all, it usually has to be translated into defined conduct.

The examiner will usually look for the central disputed issue, separate unrelated topics, remove unsuitable wording and advise whether any part of the concern can be examined responsibly.

A long question list often indicates that the matter needs scoping before an appointment can be offered. More questions do not automatically mean more useful information.

Fees are assessed case by case after confidential discussion. Relevant factors may include the issue, complexity, venue and travel arrangements, preparation, reporting and whether the matter is private, legal, workplace, therapeutic or otherwise specialist.

See the dedicated UK lie detector test cost guide for the current cost explanation.

Where the retainer policy applies, a £125 reservation retainer may be required to reserve an offered appointment. It is credited against the total examination fee and is not an additional charge.

The retainer reserves the appointment, but it does not guarantee that an examination will proceed regardless of suitability, consent, cooperation, pre-screening, professional judgment or the applicable terms.

Yes. You can submit a confidential case summary before any appointment is offered or payment requested. An initial enquiry is not the same as a confirmed booking.

No. The enquiry must be reviewed for suitability, scope, consent and practical arrangements. An appointment is confirmed only after the case is accepted, the terms are clear and the required booking steps have been completed.

1. Submit a confidential enquiry or appointment request.
2. Provide a concise summary of the issue.
3. Allow the proposed issue and question scope to be reviewed.
4. Confirm that the examinee is willing to participate voluntarily.
5. Complete any requested pre-screening or suitability information.
6. Proceed only once the appointment, fee, terms and reporting arrangements have been confirmed.

For a fuller process explanation, read the step-by-step guide to arranging a professional polygraph examination.

There is no fixed timescale. Timing depends on availability, the nature of the issue, how quickly suitability can be reviewed, whether the proposed questions are coherent and whether suitable venue arrangements can be made.

You can explain why a matter is urgent, but urgency does not remove the need for consent, suitability review and defensible question formulation. A rushed examination may be refused if the necessary checks cannot be completed responsibly.

Rearrangement and cancellation depend on the timing, the work already undertaken and the applicable terms. Review the terms of business before booking, especially where a short-notice appointment or retainer applies.

You may make an enquiry about whether a matter is suitable, but the proposed examinee must personally and voluntarily agree to participate. An examination should not proceed where consent is pressured, unclear or withdrawn.

No responsible answer should present accuracy as a simple guarantee. Accuracy depends on suitability, issue definition, question formulation, recognised procedures, data quality, examiner competence and interpretation.

A polygraph examination is not infallible and should not be treated as a standalone verdict. Read more in the polygraph accuracy guide.

No. A polygraph examination records physiological activity while the examinee answers structured questions. A trained examiner then interprets response patterns using the relevant method, scoring, case formulation and suitability information.

The instrument does not directly identify truth or deception by itself.

Ordinary nervousness is expected. A professional examination does not treat nervousness alone as deception. The examiner considers suitability, procedure, question clarity and response patterns across the examination.

Yes. No assessment is infallible. False positive, false negative and inconclusive outcomes are possible, which is why suitability review, question formulation, examiner competence and cautious interpretation matter.

An inconclusive result means that the data do not support a clear examiner opinion under the applicable criteria. It should not be treated as a deceptive result by default, and it does not automatically mean that a retest is appropriate.

In most private specific-issue matters, verbal feedback is usually discussed after recording and analysis. The exact arrangement depends on the agreed scope and whether written reporting has been commissioned.

That depends on the agreed instruction and reporting scope. Some matters require a written report; others may involve verbal feedback only. Reporting should be discussed before the appointment is confirmed.

Where a written report is required and agreed, existing guidance indicates that reports are typically provided within a few working days. The expected timescale should still be confirmed for the particular instruction and reporting requirements.

No. A polygraph result is an examiner opinion based on a structured procedure. It is not standalone proof of guilt, innocence, truthfulness or deception, and it should not be used as the only basis for a serious decision.

The examinee should normally have a reasonable opportunity to discuss the process and any significant reactions. A private specific-issue examination is not a general interrogation and should remain focused on the agreed issue.

Anxiety is relevant and should be disclosed, but it does not automatically prevent an examination and does not automatically create a deceptive result. The examiner considers whether the person can participate voluntarily, understand the questions and provide interpretable data.

A diagnosis alone does not decide suitability. The examiner may need to consider symptoms, medication, triggers, panic risk, ability to sit through the procedure, comprehension and whether any adjustments are appropriate. This page is not medical advice.

Medication can be relevant to suitability and data quality, but it does not automatically make an examination unsuitable.

Do not stop or change prescribed medication unless instructed by the prescribing clinician. Disclose medication, dosage, recent changes, side effects and any relevant sleep aids, pain medication or supplements during pre-screening.

Disclose relevant medical conditions, prescribed medication, recent medication changes, anxiety or panic symptoms, pain, sleep problems, pregnancy, neurodevelopmental conditions, communication needs, recent alcohol or drug use and anything that may affect participation.

The purpose is suitability review, not to encourage anyone to alter medication or routine without clinical advice.

Neurodevelopmental conditions do not automatically prevent examination. Suitability is reviewed individually, including attention, communication, sensory issues, anxiety, comprehension and whether any reasonable adjustments are required.

Pregnancy does not automatically preclude a polygraph examination, but it is an important consideration. It should be disclosed during the initial enquiry so suitability can be assessed before any appointment is confirmed.

If the examiner decides that the examination cannot responsibly proceed, it may be postponed, modified or declined. Reasons may include consent concerns, health or medication issues, inability to understand the questions, unsafe conduct, non-cooperation or poor suitability for the proposed format.

Any fee consequences depend on the terms and the circumstances. Review the terms of business for the general framework.

No. Take prescribed medication as directed unless a healthcare professional tells you otherwise. Eat normally, stay reasonably hydrated and avoid unusual heavy meals, excess caffeine, high-caffeine energy drinks, alcohol and recreational drugs.

See the preparation guide and the pre-screening information.

No. A private examination requires voluntary participation and informed consent. If consent is not freely given, the examination should not proceed.

You can make an enquiry and ask whether the issue might be suitable, but the proposed examinee must personally agree to participate. An instruction based on pressure, threats or coercion may be refused.

For more context, see the guidance on whether you can force a partner to take a lie detector test.

Workplace instructions may involve employment, HR, legal, data protection, safeguarding and consent issues. They are specialist instructions and should not be treated as ordinary private public enquiries. Legal or HR advice may be needed.

Yes. Consent can be withdrawn. Depending on when and why that happens, the examiner may stop, postpone or decline the examination. The fee position depends on the terms and the circumstances.

If coercion, threats, intimidation or unsafe pressure are suspected, the examiner may refuse or stop the examination. Safeguarding, legal or professional steps may be taken where required or appropriate.

The matter is handled confidentially, subject to consent, reporting arrangements, data protection, legal obligations, safeguarding, professional duties and the terms of business. It should not be described as completely confidential in all circumstances.

The result is provided according to the agreed instruction and the examinee consent arrangements, subject to law, privacy obligations and any specialist reporting terms. In private instructions, the client and examinee positions should be clarified before the appointment.

A written report is sent only according to the agreed reporting arrangement and consent position, subject to legal, privacy, safeguarding and professional obligations. Reporting should be agreed before the appointment proceeds.

Yes, where appropriate. Reports can be directed to solicitors, legal representatives, therapists, employers or other professionals where the instruction, consent, lawful basis and reporting scope support that arrangement. Specialist instructions may involve different procedures and terms.

Admissibility and evidential use depend on jurisdiction, case type, procedural rules and the purpose for which a report is offered. Do not assume that a result will be admissible or inadmissible without legal advice on the specific matter.

The police are not automatically informed simply because an examination is requested. Disclosure may be required or appropriate where law, safeguarding, threats, criminal conduct, court obligations, regulatory duties or professional obligations apply.

The terms state that, unless otherwise agreed or required for legal, regulatory, safeguarding, contractual, dispute or other specified purposes, recordings and related data may be deleted from records within 24 hours after the examination.

Wider client, matter, forensic, evidential, financial or professional records may be retained for longer under the privacy policy and applicable legal or professional requirements.

A typical private specific-issue appointment should ordinarily be allowed approximately two to three hours. Particularly straightforward or complex matters may take less or more time. Specialist services may use different appointment structures and durations.

The appointment commonly includes arrival and administrative checks, consent confirmation, suitability review, issue discussion, question review, physiological recording, analysis, post-examination discussion, verbal feedback and any agreed reporting arrangements.

For more detail, read the professional appointment guide.

Read any instructions provided, complete requested pre-screening information, bring any agreed documents, eat normally, take prescribed medication as directed and disclose relevant health, medication or communication issues.

Do not arrive under the influence of alcohol or recreational drugs. The preparation guide gives more detailed practical guidance.

Yes. Eat normally and stay reasonably hydrated. Avoid fasting, dehydration, unusually heavy or unfamiliar meals, excess caffeine, high-caffeine energy drinks, alcohol and recreational drugs.

A companion may usually accompany the examinee to the office or location, but will not normally be present in the examination room. Accessibility, communication, vulnerability or safeguarding needs should be discussed in advance.

No. A professionally conducted polygraph examination requires physical presence, in-person instrumentation and a controlled environment. That cannot be replicated through a remote video call.

The venue must be suitable, private and controlled. Home or off-site arrangements require case-by-case review and may be declined if the environment is unsuitable, unsafe, distracting or not sufficiently private.

UK arrangements depend on examiner availability, suitable venues and the needs of the case. See the UK lie detector test location information, and confirm the final venue during the booking process.

It may help address one carefully defined factual issue, but it cannot repair trust, determine emotions or resolve every aspect of a relationship dispute. Some matters are better approached through advice, therapy or safeguarding support rather than a polygraph examination.

A suitable examination may address defined conduct during a defined period, such as whether specified sexual contact occurred or whether a specified communication was sent. It cannot responsibly examine an entire relationship history in one broad question.

Normally no. Broad whole-relationship questions are usually unsuitable because they are too vague, expansive and emotionally loaded for a specific-issue examination.

The terms must be defined before any question is used. Labels such as cheating, betrayal, contact or inappropriate behaviour may mean different things to different people. The examiner may need to translate those labels into specific conduct, or decline the issue if that cannot be done fairly.

No. Instructions may be declined where consent, safety, coercion, vulnerability, question formulation, proportionality or professional defensibility is problematic.

Look for careful suitability review, informed consent, clear scoping, defensible question formulation, realistic claims, transparent terms, appropriate reporting arrangements and relevant professional competence. Be cautious about guaranteed outcomes or claims that reduce the process to a simple pass-or-fail promise.

Question formulation determines what the examination is actually about. Poor wording can make results less interpretable even when everyone attends in good faith. The question-formulation guidance explains why behavioural, time-limited and single-issue wording matters.

No. More question slots do not necessarily produce better information. A narrower, properly formulated examination is often more defensible than a broad list of weak or unrelated questions. The question-limit guidance explains this in more detail.

Not necessarily. Price should be considered alongside suitability review, ethical practice, question formulation, examiner competence, data quality, confidentiality, reporting and the terms that apply to the instruction.