Lie detection tests for convicted domestic abuse offenders is a costly distraction

One of the more striking features of the government’s draft domestic abuse bill, which was published 21 January, was the proposed extension of the ‘polygraph condition’ to convicted offenders’ licences.

The ‘polygraph condition’ already has a statutory base in the Offender Management Act 2007, but it is presently limited to those who have been convicted of serious sexual offences.

If passed in its current form, the domestic abuse bill would introduce the polygraph condition as a permissible feature of the licence for an offender convicted of a specified domestic abuse offence.

The introduction of polygraph testing to the bill received significant media coverage but it is questionable what impact the scheme will have, aside from its financial cost.

The government’s impact assessment estimates that a three-year pilot of the scheme would cost in the region of £500,000 per year (a total cost across the three-year pilot of £1.5m).

On the basis of that the three-year pilot is expected to involve just 300 offenders, that would make the cost per offender £5,000. Against the background of austerity cuts which have taken the criminal justice system to the brink (if not beyond), these figures are significant.

Therefore, it would not be unreasonable to expect that polygraph testing would have a significant impact.

The criteria

However, at a stroke, the statutory pre-conditions remove polygraph testing from all but the most serious matters. For the condition to be available, an offender must:

1. Be over 18 years old on the day that they are released on licence;
2. have received a “relevant custodial sentence”; and
3. the “relevant custodial sentence” must be in relation to a “relevant offence involving domestic abuse”.

“Relevant custodial sentence” is defined by §28(3) Offender Management Act 2007 and excludes any sentence of less than 12 months.

The scope is further limited by the fact that it is not considered appropriate to polygraph test those with serious mental illness or memory impairments. Disappointingly, those with learning difficulties can (presently) be tested ‘with some caution’. 

Even where an offender is eligible for the polygraph condition to be imposed, inherent limitations of polygraph testing were explicitly recognised in Prison Service Instruction 36/2014:

“It is important to note that an examinee can only respond to a question (verbally or physiologically) to the best of his or her knowledge. This is an important issue with using polygraphy or any other tool designed to detect deception or facilitate truth telling.

“The technology is based on the interviewee’s reaction to the question posed. Therefore, it does not assess the objective truth; it only interrogates the participant’s subjective perceptions of what s/he thinks the question is asking.”

The limitations are also reflected in the severely limited use of polygraph tests in the criminal justice system. §30 Offender Management Act 2007 acts as a statutory bar to the use of a failed polygraph test in criminal proceedings.