Truth is, lie detectors have no place in any civilised society

Truth is, lie detectors have no place in any civilised society

Police trialling the technology in Britain sounds a warning for the justice system here, DAVID BILES writes

Arecent article in the London Daily Telegraph under the heading ''Police trialling lie detector tests in Britain'' should be a matter of great concern to all British citizens, but also to all Australians as we tend to follow Britain in many areas of law enforcement and criminal justice. It would be a dangerous trend if we started down that path.

Lie detectors, which are also known as polygraphs, do not actually measure whether an individual is telling lies or telling the truth. What they do is record a person's involuntary physiological responses (such as pulse, blood pressure and perspiration) while under interrogation as an indication of the veracity of any statements he or she makes.

There may be some link between stress and these measures, but this has never been rigorously tested and the possibility of mistakes is very high.

Perhaps the British police are not aware of a report issued by the National Academy of Sciences in 2003, ''The Polygraph and lie detection'', which found that most polygraph research was ''unreliable, unscientific and biased''.

The almost irresistible urge to improve the effectiveness and efficiency of policing by the use of smart gadgets, such as stun guns, is possibly why British police forces over many years have conducted trials to assess the possible use of lie detectors.


This has reached the point now where the Association of Chief Police Officers has established a working group to advise forces contemplating using this technology.

And it doesn't stop there. The British Ministry of Justice, possibly one of the most cautious government departments to be found anywhere, is expected to decide next year whether sex offenders should be required to take routine lie detector tests as a condition of their parole following several years of debate between ministers on this subject.

Some commentators have even suggested that lie detectors are being used by parole officers to determine whether paedophiles and rapists on parole should be returned to jail if they fail the test. If this is already happening, it is only a small step to using them to determine guilt or innocence in the courts.

Mercifully, there is no talk yet of lie detectors providing evidence in British courts as is allowed, at the discretion of the presiding judge, in 19 of the 50 states in the US. In Britain it is suggested that lie detector tests would only be used by police as an investigative tool, as an addition to the ''armoury of investigative techniques'' available.

The main danger of allowing lie detectors anywhere near the criminal justice system is the very high number of ''false positive'' cases that will be identified. These are cases where the machine results suggest that the individual was lying and is therefore guilty of the offence for which he or she is accused.

There is also the problem of ''false negatives''; people who are lying when doing the test and are therefore not pursued further by the police, or, if the test is in a court setting, are acquitted of the charges against them.

Some people in this category may even have been coached in counter-measures to beat the machine, for example, by appearing very relaxed and friendly with the person asking the questions.

It is widely accepted by criminologists that perhaps 1 or 2 per cent of convicted people in prison are genuinely innocent, but a highly respected English academic has argued that if polygraph evidence is permitted, that percentage will increase to between 5 and 10 per cent. That would be hardly likely to increase public respect for either the police or the courts.

The other significant danger is that lie detectors are likely to be used in many other aspects of life quite removed from the world of crime and criminals. An obvious target area for those advocating the use of these devices is in the context of job interviews to see if applicants are exaggerating their qualifications or experience. A similar area for their possible use would be in the workplace to identify any workers who are suspected of theft. Another possible use listed by the industry is infidelity testing.

These distasteful possibilities are already to be found in the advertisements that the purveyors of these devices place in magazines and on their websites.

These sources of information also promote discussion of future developments in this industry which will include what might be called surreptitious lie detecting where the target individual is not aware of being tested.

Possible locations for such tests would be the customs and immigration counters at airports.

In short, the whole polygraph industry must be seen as unacceptable in a civilised society. It might be fun to see lie detectors used in light-hearted game shows on television, but they have no place in the real world, and certainly no place in our police forces or our courts.

A further concern is the fact that lie detectors are easily purchased on the internet and elsewhere, and the sellers always promote themselves as professionals by stating that they are ''full members of the British Polygraph Association''.

The machines are relatively inexpensive and may be obtained by anyone who wants them without any questions being asked about the uses to which they may be put.

In the course of exploring this subject I was astonished to discover that the security company that I had engaged several years ago to install an alarm system in my house also sells a wide range of lie detectors! Perhaps I chose the wrong company.

If this were not such a serious and potentially dangerous subject perhaps the best response to it would one of ridicule or derision, but if that does not work the next option would be for governments to legislate to make the machines illegal.

David Biles is a Canberra-based consultant criminologist.

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