Any polygraph-related FAQ webpage usually features a question – does a polygraph test hold up in court? In the UK criminal justice system, lie detectors’ results are not admissible as evidence. The exception to criminal justice admissibility of polygraph evidence is sex offenders’ cases, but the use of polygraphs in such cases is very heavily regulated. The answer to the question “why are lie detector tests not admissible in court” is that it has been held that they are not sufficient indication of credibility. The same applies to UK’s military tribunals – polygraph evidence is never admissible in the military court, or the MCS as it is more commonly known.


US Law Enforcement Agencies

Law enforcement agencies in the US use polygraph tests on a regular basis, but the trend is not very prominent in the UK, mostly because of the issues of polygraph admissibility. However, certain officers are trained in the use of polygraph for court cases because of the recent law allowing polygraph evidence to be admissible in criminal court in cases of high-risk sex offenders mentioned above.

The use of polygraph test by intelligence service agents is very common in the US, but less so in the UK. However, the technology is evolving and it is very possible that the UK agents might employ polygraph tests more in the near future.


UK Local Authorities

Local authorities in the UK have used polygraph evidence on several occasions catch several fraudulent benefits claimants. The evidence was gathered by phone lie detector tests. It is impossible, however, to base a case of a fraudulent claim on such evidence alone. Nevertheless, local authorities continue employing this method as starting points of investigations. Sometimes, a private investigator can get involved.


Business Disputes

When it comes to business disputes within the private sector, unlike the US where the lie detectors’ evidence is often admissible, in the UK it is much harder to use polygraphs in court. That is not to say, however, that polygraph evidence can never be admissible in court. The level of certainty of a polygraph is far too low for criminal cases, but it can, on certain occasions, be enough for a civil dispute. Polygraph admissibility is at the judge’s discretion. For example, results of a polygraph test conducted during a job interview screening which could include, for example, drug and alcohol-related questions, can serve as evidence in dismissal cases.


Private Disputes

In private disputes between physical persons, polygraph test evidence can also be admissible. For instance, in divorce hearings, a private investigator can present evidence he or she has obtained per customer’s request about the customer’s spouse and whether or not he or she has engaged in an extramarital affair. In some divorce cases, infidelity can play a role in dividing marital assets and therefore, the lie detector test evidence would be significant for the case.

Evidence gathered by agencies that provide professional polygraph testing services can be just as admissible in certain civil cases as the related evidence gathered by a private investigator. The clientele that is likely to use such agencies for that purpose mostly consists of companies and government organizations.