Terrorists, paedophiles and rapists could be considered for greater freedoms on their release if they pass lie detector tests, the Sunday Telegraph can disclose.

As the Government increases the number of high-risk criminals who can have the tests added to their conditions of licence, official documents show that evidence of whether they work is “neither extensive nor of good quality”.

Despite concerns over accuracy, probation workers have been instructed to tell those offenders to whom the polygraph test applies that it can be “protective” for them and could “be a possible route to having licence restrictions reviewed”.

The Ministry of Justice insisted that the results of the test alone could not lead to the relaxing of licence conditions as they are part of a range of assessment tools which would need to show the offender had complied with all of their conditions over a long period of time.

High risk of reoffending

The Government has increasingly expanded its use of polygraph tests to monitor serious criminals upon their release on the basis they are “80 to 90 per cent accurate”.

In January it announced that it would carry out a pilot test with the most serious domestic abusers including murderers, who are considered to be at high risk of reoffending.

Such tests have been carried out on serious sexual offenders since 2007 and additional powers to use them on “high risk” terrorists were announced last year.

But Coral Dando, professor of forensic psychology at the University of Westminster, who has researched ways of detecting deception among offenders, said that she was “sceptical” about their use and that people “can get courses on how to pass a lie detector test on the internet”.

She said using it as a risk assessment tool was “extremely problematic” and it has the potential to give offenders confidence that “they can beat the test, so they don’t need to behave”.

Prisoners can only be required to carry out polygraph tests as part of the conditions of their release if they are convicted of serious offences related to terrorism, sexual offences and domestic abuse and have been given a custodial sentence of more than 12 months.

The Government has insisted the tests are merely an additional tool to monitor those likely to reoffend and therefore ensure public safety.

In official documents governing their use`, seen by the Sunday Telegraph, it says it is “important” that offenders should understand that as well as “risk management” the polygraph condition can be “protective to them” if they comply with their licence conditions.

“It can, for example, be a possible route to having licence restrictions reviewed if, through managing their own behaviour, the assessment of the supervised individual’s risk of serious harm is lowered,” the document notes.

When a criminal completes “several successive” tests which indicate they are “not deceptive” then it could “alongside the individual’s general response to supervision and progress against supervision objectives, allow an adjustment downwards of the individual’s risk of serious harm”.

The results of the polygraph cannot be used as evidence in court, but information revealed during the sessions can be used to consider recalling an offender to prison or placing greater restrictions on their movement. 

If a trained specialist who carries out the examination thinks that victims or members of the public are at risk they should call the police for victim support, the guidance written in August states.

It notes that while the evidence to support polygraph testing is lacking, that which is available suggests that “it can achieve above chance levels of accuracy”. One study has found that it “significantly increases the likelihood that examinees will make disclosures that are pertinent to the assessment and management of their risk”, the guidelines state.

But there has been widespread concern about the use of polygraph testing, including from the Law Society which told Parliament it “does not agree that the polygraph condition should be placed on individuals released on licence”.

Beat the test

Professor Graham Towl, the former head of psychology for the Prison Service and the Ministry of Justice, warned that “the chief problem with the ‘lie detector’ is that it doesn’t work”.

He said that studies have shown that you can teach people to beat the test and that more effective interview techniques would give a fuller picture.

Prof Dando, a former police officer, added: “My concern is that I think that organisations will start to rely on this as methods for countenancing the decisions that they make.

“People can very quickly and very easily learn to beat a lie detector test and I just think that the risks involved outweigh potential benefits.”

She said that while she understood the desire for the tests to work, there is “no empirical evidence” and it is being used on people such as sex offenders “who have learned throughout their life to cover their tracks, have had to keep their desires a secret and private, they are very practised deceivers”.

The MoJ said that of more than 5,000 tests which have been undertaken with sex offenders, two-thirds of them had resulted “in significant disclosures”.

A spokesman said: “Evidence shows polygraph testing works. They are always used in addition to close supervision, behaviour treatment and strict conditions on offenders’ movements and contact with victims.

“Over 3,300 polygraph tests carried out by the Probation Service since 2014 have provided invaluable information we would otherwise not have had about offenders’ behaviour helping us to better protect the public.”