A former senior civil servant at Ministry of Justice has condemned Government plans to introduce more lie detector testing for ex-prisoners. Speaking to the prisoners’ newspaper Inside Time, Professor Graham Towl, who used to be the MoJ’s chief psychologist, highlighted his concern about their use saying that the technique ‘doesn’t work’ as ‘you can teach people to lie effectively on a polygraph’.
Polygraph tests, also known as lie detector tests, measure the subject’s breathing, heart rate and sweat responses while they answer questions. Elevated readings are viewed as a possible indication of stress due to lying. Since 2007, the technique has been used on serious sex offenders on parole and from 2014, mandatory tests have been added to some offenders’ release conditions. The polygraph is not admissible as evidence in court and there is no legal framework to prevent police forces using it during interrogations or as part of evidence gathering.
Towl also spoke out about the ethical implications of the technique. Some supporters of polygraph testing argue there is higher possibility of the disclosure of information as the subject may believe that the machine will detect their lies. The Government previously has highlighted the ‘significant evidence to demonstrate the efficacy of polygraph testing’. Of 5,000 polygraph tests conducted, two-thirds resulted in significant disclosure.
However, Towl believes there is an ‘ethical issue…about deception’. He added that there is significant evidence to suggest other techniques of extracting more information were more beneficial.
The Ministry of Justice claims the tests are reliable saying ‘when used correctly, polygraph tests are 81 to 91 per cent accurate’.
Since 2014, the Government has used mandatory polygraph examinations on domestic abuse perpetrators released on licence identified as being at high risk of causing serious harm. The Government justified the use as providing an ‘additional source of information’ in order to help make future decisions about the ex-offenders.
The Counter-Terrorism and Sentencing Bill will also extend their use to people convicted of terrorist offences. This plan also received criticisms. Professor Ormeord, at the University of Sussex, described how the technique is ‘deeply flawed and potentially dangerous’. In 2015, research conducted by the university found that well-designed interviews were ’20 times more effective’ than other methods.