This guidance post is intended for members of the public who are considering commissioning a polygraph examination in connection with infidelity, trust, or other relationship concerns. It draws on the British Polygraph Society’s Code of Ethics (2026, v1.0) and Standards of Practice (2026, v1.0). Full references appear in the Sources section.

Key points

  • A relationship polygraph is a voluntary, structured test of specific factual claims — it is not therapy, not mediation, and not a deterministic truth machine.[1]
  • Informed written consent is mandatory, and it must be freely given — coercing a partner into a polygraph is ethically prohibited.[2][3]
  • Results are probabilistic, not absolute — examiners must not overstate the reliability of the technique.[4]
  • A competent examiner will provide a written report, charge no contingent fees, and maintain strict confidentiality.[5][6]
  • Prepare emotionally for any outcome — including an inconclusive result — and consider professional counselling support regardless of the test’s findings.[7]

Why people seek a relationship polygraph

People arrive at the decision to commission a polygraph examination for a range of deeply personal reasons. The most common include:

  • Suspicion of infidelity. One partner believes the other has been unfaithful and wants a factual resolution that conversation alone has not provided.
  • Rebuilding trust after disclosure. An affair or other breach of trust has already been acknowledged, but the injured party needs assurance that the full truth has been shared.
  • Resolving a specific factual dispute. A disagreement over a discrete event — financial dishonesty, hidden contact with a third party, or similar — has become irreconcilable without an independent assessment.

Each of these situations carries significant emotional weight. It is important, before proceeding, to understand exactly what a polygraph examination involves, what it can realistically offer, and where its boundaries lie.

What a relationship polygraph can do

A properly conducted relationship polygraph provides a structured, evidence-based test of specific factual claims. It measures physiological responses — such as changes in respiration, cardiovascular activity, and electrodermal activity — while the examinee answers carefully formulated questions. The examination must follow validated techniques,[8] and the examiner scores the physiological data according to standardised protocols.

The result is reported as one of three outcomes:

  • Deception Indicated (DI) — the data suggest the examinee was not truthful on the relevant questions.
  • No Deception Indicated (NDI) — the data suggest the examinee was truthful on the relevant questions.
  • Inconclusive (INC) — the data are insufficient to support either conclusion. This is a legitimate outcome, not a failed test.[9]

When conducted by a qualified examiner under proper conditions, the test can provide a meaningful additional data point in situations where trust has broken down and verbal assurances are no longer sufficient.

What it cannot do

A polygraph is not a substitute for therapy, counselling, or relationship mediation. It addresses narrow factual questions. It does not diagnose the health of a relationship, assign blame, or determine what either partner should do next.

Several misconceptions deserve correction:

  • It is not a deterministic truth machine. Results are probabilistic. A qualified examiner will never guarantee certainty; indeed, BPS members are specifically prohibited from overstating the reliability of the technique.[10]
  • It cannot read minds. The polygraph records physiological responses associated with deception; it does not directly detect lies or reveal hidden thoughts.
  • It will not fix a relationship. Even a clear NDI result does not undo the circumstances that led to the test. Equally, a DI result provides factual information but no guidance on what to do with it.
  • It cannot answer vague questions. “Has my partner ever lied to me?” is not a testable question. The polygraph works on specific, bounded, falsifiable propositions.

How it works in practice

A standard polygraph examination proceeds through three phases:

1. Pre-test interview

The examiner meets the examinee to explain the process, discuss the issues under investigation, and develop the specific test questions together. No question asked during the test should come as a surprise. This phase also includes obtaining informed written consent[11] and a thorough explanation of the examinee’s rights.

2. In-test (chart collection)

The examinee is connected to polygraph sensors and the agreed questions are presented in a structured format. Several charts are collected to ensure reliability.

3. Post-test

The examiner analyses the physiological data using a validated scoring system[12] and communicates the result (DI, NDI, or INC) to the examinee. A written report is then prepared.[13]

The entire process typically takes between 90 minutes and two hours for a single-issue examination.

Both parties must understand that a polygraph examination is entirely voluntary. The person being tested must give informed written consent freely and without pressure.[14]

Coercing, pressuring, or emotionally manipulating a partner into taking a polygraph is ethically unacceptable. The BPS Code of Ethics expressly states that a polygraph examination must not be used as a tool of coercion or punishment.[15]

If you are the person requesting the test, ask yourself honestly: is your partner genuinely willing, or are they agreeing under duress? If you are the person being asked to take the test, know that you have every right to decline. No reputable examiner will proceed if there is any indication that consent has been coerced.

Consent must be obtained from the examinee directly. A competent examiner will ensure that the examinee understands the process, the nature of the questions, the possible outcomes, and the limits of the technique before proceeding.

Ethical standards for relationship testing

Relationship polygraph testing raises particular ethical challenges because of the emotional dynamics involved. Core standards that apply under BPS governance include:

  • Informed written consent obtained directly from the examinee.[16]
  • Neutral conduct throughout the examination — the examiner must not take sides, advocate for either party, or become involved in the relationship dispute.[17]
  • No contingent fees — the examiner’s fee must not depend on the outcome of the test.[18]
  • Confidentiality — results belong to the examinee and must be handled in accordance with confidentiality obligations.[19]
  • No questions on protected characteristics unless directly relevant to the examination purpose and with the examinee’s explicit consent.[20]
  • Written report provided after the examination.[21]
  • No use as punishment or coercion.[22]

For information on your rights as an examinee, see Your Rights.

Good practice vs common bad practice

Ethical relationship polygraph testing: what to expect and what to avoid
Good practice Common bad practice
Informed written consent obtained directly from the examinee, without pressure[23] Partner signs a consent form with the other partner present and applying emotional pressure
Examination conducted in a neutral, professional setting Testing conducted in a private residence or the requesting partner’s workplace
Examiner remains strictly neutral; focuses solely on credibility assessment[24] Examiner offers relationship advice, takes sides, or acts as mediator
No persons with a personal interest present during the examination Requesting partner sits in the room or listens via audio/video link during the test
Written report provided to the examinee[25] Only a verbal result given, with no documentation
Flat fee charged regardless of outcome — no contingent fees[26] Fee varies depending on whether the result is DI or NDI, or “bonus” charged for a “passed” test
Examiner uses validated scoring techniques[27] Examiner relies on subjective impressions or unstandardised methods
Inconclusive reported honestly as a valid outcome[28] Examiner forces every test into a DI or NDI category, never reporting inconclusive
Examiner does not overstate the reliability of the technique[29] Examiner claims the test is “100% accurate” or guarantees the truth

Choosing an examiner

Your choice of examiner is the single most important decision in this process. Look for the following:

  • Accredited training. The examiner should have completed a recognised polygraph training programme that meets or exceeds the minimum curriculum standards of a body such as the American Polygraph Association (APA).
  • Membership of a professional body. BPS membership indicates that the examiner has agreed to abide by the Society’s Code of Ethics and Standards of Practice. You can search the BPS directory for members in your area.
  • Written report. Ensure the examiner will provide a formal written report after the examination.[30]
  • No contingent fees. The fee should be a fixed amount regardless of the test outcome.[31]
  • Willingness to explain the process. A competent examiner will answer your questions about the technique, its limitations, and the procedure before you commit.
  • Professional setting. The examination should take place in a neutral, professional environment — not in your home or your partner’s home.

Beware of examiners who guarantee a particular result, claim 100% accuracy, refuse to provide credentials, or insist on unusually fast turnarounds without proper pre-test procedures.

Emotional considerations

Before booking a polygraph, ask yourself: am I prepared for any outcome?

A relationship polygraph can produce three results, each of which carries emotional consequences:

  • No Deception Indicated. This may bring relief, but it does not automatically restore trust. The underlying issues that led to the test may still require work.
  • Deception Indicated. This may confirm fears, but it does not tell you what to do next. The emotional impact can be significant, and professional support may be valuable.
  • Inconclusive. This is a valid scientific outcome[32] but can be deeply frustrating for both parties. It does not mean the examinee was deceptive; it means the data were insufficient for a determination.

Consider the following before proceeding:

  • Have you discussed with your partner why you feel a polygraph is necessary? Open communication — even difficult communication — may sometimes achieve more than a test.
  • Would professional relationship counselling be a more appropriate first step, or a useful complement to the examination?
  • If the result is DI, what will you do? If it is NDI, will you genuinely accept it? If it is INC, can you live with the ambiguity?
  • Is either party in a vulnerable emotional state that might make the examination inadvisable at this time?

A polygraph provides information. What you do with that information is a personal decision that no examiner can make for you.

Limitations and honest expectations

Honesty about limitations is a hallmark of ethical practice. The following points are important:

  • Results are probabilistic. No physiological test achieves perfect accuracy. Examiners must not overstate what the technique can deliver.[33]
  • The polygraph tests specific questions, not general character. A result applies only to the questions asked during that examination.
  • A polygraph result is not legally binding. In England and Wales, polygraph results are not generally admissible as evidence in court proceedings. The test is a private assessment, not a legal determination.
  • It cannot undo harm. Whether the result is DI, NDI, or INC, the test itself does not repair a relationship. It provides one piece of information in a much larger picture.
  • Not every situation is suitable for polygraph testing. Some disputes are too vague, too emotionally charged, or too complex for a meaningful polygraph examination. A responsible examiner will tell you so.

If you have further questions about the polygraph process, your rights as an examinee, or how to find a qualified examiner, the BPS provides public information on the Your Rights page.

This guidance is provided for general informational purposes. It does not constitute legal advice, therapeutic advice, or a recommendation for or against polygraph testing in any particular case. If you are experiencing relationship difficulties, you may wish to seek support from a qualified counsellor or therapist. If you are in a situation involving domestic abuse or coercive control, please contact a specialist service such as the National Domestic Abuse Helpline (0808 2000 247).

BPS
British Polygraph Society — an unincorporated UK membership body for polygraph examiners, founded in 2017.
APA
American Polygraph Association — a US-based professional body that sets training and practice standards for polygraph examiners.
DI (Deception Indicated)
A polygraph test outcome in which the physiological data suggest the examinee was not truthful on the relevant questions.
NDI (No Deception Indicated)
A polygraph test outcome in which the physiological data suggest the examinee was truthful on the relevant questions.
INC (Inconclusive)
A polygraph test outcome in which the physiological data are insufficient to support a determination of either deception or truthfulness. This is a valid scientific outcome.
EDA (Electrodermal Activity)
Changes in the electrical conductance of the skin, caused by sweat gland activity. One of the physiological channels measured during a polygraph examination.
CQT (Comparison Question Test)
A polygraph testing format that compares physiological responses to relevant questions (about the matter under investigation) with responses to comparison questions (broader questions designed to elicit a known response pattern).
Validated technique
A polygraph testing and scoring method whose accuracy has been established through peer-reviewed research, as required by BPS Standards of Practice §8.1.
Contingent fee
A fee arrangement in which the examiner’s payment depends on the outcome of the examination. Prohibited under BPS Code of Ethics §3.
Informed consent
Agreement to undergo a polygraph examination given voluntarily by the examinee after receiving a full explanation of the process, the questions to be asked, the possible outcomes, and the limits of the technique.
Pre-test interview
The phase of a polygraph examination before chart collection, in which the examiner explains the process, discusses the issues, develops test questions with the examinee, and obtains consent.
Post-test
The phase of a polygraph examination after chart collection, in which the examiner analyses the data and communicates the result to the examinee.
CPD
Continuing Professional Development — ongoing training and education required to maintain professional competence.
UK GDPR
The UK General Data Protection Regulation — the data-protection framework that governs the processing of personal data in the United Kingdom, relevant to how polygraph results and personal information are stored and shared.

Sources

  1. British Polygraph Society (2020). Standards of Practice, v1.0. Available at: polygraph.org.uk/standards-ethics/standards-of-practice/.
Tags apa code-of-ethics standards-of-practice
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