The short answer
If a client has taken a polygraph and you want to know whether the result can be trusted, an independent review can help you answer that. It will not turn a polygraph into evidence, and it will not remove the risks of the original test.
This guide is for lawyers and for people working with a lawyer. It is general information, not legal advice, and it does not cover the rules of any particular jurisdiction.
What "independent scoring" means
A second examiner, who was not part of the original test, re-scores the recorded charts and reviews how the test was run. Done properly, it looks at two things: whether the scoring is supported by the charts, and whether the procedure gave the charts a fair chance of meaning anything.
| Part of the review | What it checks |
|---|---|
| Chart scoring | Whether a second examiner reaches the same conclusion from the same recorded charts. |
| Question list | Whether the questions were clear, relevant and fairly built, and whether the client understood them. |
| Procedure | Whether the pre-test interview, the number of charts and the conditions followed a recognised structure. See the four phases. |
| Recording quality | Movement, interruptions, artefacts and anything that makes a chart hard to read. |
| Client factors | Documented medical conditions, medication, fatigue or distress that may affect the signals. See medical conditions. |
What a lawyer can realistically expect
- A quality check. A review can show whether the original result rests on a sound test or on a weak one.
- A basis for questions. Concrete concerns about the procedure are more useful in a conversation with the other side than a general complaint that polygraphs are unreliable.
- Not admissible evidence. Whether a polygraph or a review of one can be used in court is a legal question that depends on the place. See US courts, Philippine courts and Australian courts.
- Not a guarantee of a different result. The second examiner may agree with the first.
Be careful with accuracy figures
You will find published figures for how often blind reviewers agree with original examiners. A 1990 review in the journal Polygraph of studies of real cases reported high agreement between blind evaluators and original examiners, but its author cautioned that blind analysis of charts is not a complete measure of reliability.
The US National Research Council went further. It found observational field studies of polygraph are plagued by selection and measurement biases, that they frequently lack a clear and independent determination of truth, and that they are highly likely to overestimate real-world accuracy. A reviewer's agreement rate quoted from such studies should not be presented as proof that a result is right or wrong. See how accurate a polygraph really is.
Steps before you commission a review
- Decide the legal question first.Is the aim to understand the result, to negotiate, or to support an appeal? The answer affects what, if anything, should be done.
- Ask about confidentiality and consequences.A review may confirm the original result. Whether its findings are protected depends on the jurisdiction and how the work is arranged, so settle this before anything is commissioned.
- Get the full record.Complete charts and recordings, the question list, the report and the examiner's notes, and any consent forms. A one-line result cannot be reviewed.
- Ask for a written, specific review.It should say what was checked and which findings rest on the charts and which on the procedure.
- Keep a clear line between the review and the advice.The reviewer explains the test. You decide what it means for the case.
Related reading
For the client's side, read how to appeal a failed polygraph and polygraph remediation.
This guide is general information, not legal advice. The sources include a 1990 industry-journal abstract and an article by a private examiner, both cited for context only. Rules on admissibility, privilege and expert evidence differ by jurisdiction.
Frequently asked questions
What is independent polygraph scoring?
Will an independent review make a result admissible?
How reliable is blind chart review?
What does a lawyer need to obtain for a review?
Is a review risky for the client?
Sources
- National Research Council: The Polygraph and Lie Detection, executive summary (2003)
- Ansley, N. Validity and Reliability of Polygraph Decisions in Real Cases, Polygraph 19(3), 1990 (NCJRS abstract)
- Bassett, J. Can a Polygraph Test Help Your Client? Michigan Bar Journal, October 2002 (by a private polygraph examiner)
Working with a client who failed a polygraph?
We explain the procedure, the questions and the limits of the result in plain terms, so you and your client can decide what to do next. We do not replace legal advice.