Someone has been stealing from my girlfriend's workplace (not her) and they're forcing everyone there to undergo a lie detector test or lose their jobs. Since such tests don't actually work, is this even legal?

I have done some research but I can't get a straight answer under UK law, as the web mostly mentions US law.

  • In general in the UK is there any prohibition on an employer firing employees for refusing to answer work-related questions? If not, is there any reason to believe it would be illegal to require them to answer the questions while wired to a gizmo that causes no pain?
    – feetwet
    Jul 20, 2015 at 14:20
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    I don't know about the first bit, but the fact that polygraph testing has a huge false positive rate and the fact that it could falsly implicate people is why it shouldn't be legal
    – user175
    Jul 20, 2015 at 14:23
  • Then you have posed two separate questions, and perhaps you only meant to pose the second. (1) Can an employer fire employees for refusing to undergo a polygraph interrogation related to their work? (2) Can an employer take any action based on the results of polygraph readings during an interrogation? If your question is only the latter you should edit it accordingly.
    – feetwet
    Jul 20, 2015 at 15:03
  • Nah the question was mainly the first, but that then leads into the second I guess
    – user175
    Jul 20, 2015 at 15:28
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    @JamesHughes it seems highly irregular for a company not to have called the police if there had been theft in the workplace. If my employer fired me after their own investigation indicated that I had done something like that, I would think I ought to be able to go after them for making the decision on the basis of a substandard investigation.
    – phoog
    Jul 23, 2015 at 3:22

1 Answer 1


From Private Investigators UK:

Polygraph testing is 100 per cent, totally, completely legal in the United Kingdom. However, there are a few conditions. The person undergoing the polygraph exam must be cooperative and willing to take the polygraph. No one can be forced to take one. The person administering the polygraph test must be qualified to do so and must hold a relevant degree and license. These results however, are inadmissible in a court of law. This is because there is a fair chance of the results of a polygraph being inaccurate. Since physiological responses are measured, it is possible that the stress of the situation may cause the examinee to register many false positives.

As the results are inadmissible in a court, I think there would be reasonable grounds to claim unfair dismissal if she were sacked because of the test's results.

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