An Evaluation of Polygraph Testing by Police to Manage Individuals Convicted or Suspected of Sexual Offending

This report presents results of research commissioned by the police to evaluate their use of polygraph testing with individuals convicted or suspected of committing a sexual offence. Police areas involved in this research were: Greater Manchester (GMP), Hertfordshire, Essex, Kent, South Yorkshire, and Northumbria. Additional areas (i.e., Lancashire, Norfolk, and Staffordshire) supplied data on polygraph tests conducted for them.

The University of Kent was commissioned to evaluate police use of polygraph testing from 3rd July, 2017 to 15th July, 2019. The evaluation described in this report refers to analyses of:

• Strand 1 (Supervisees): 557 individuals convicted of sexual offending and undergoing police supervision who were randomly assigned to polygraph testing (voluntary or mandatory1 depending on police area) or comparison groups.

• Strand 2 (Suspects): 142 individuals suspected of committing online sexual offences and undergoing police investigation who were assigned to polygraph or comparison groups.

• Strand 3 (Applicants): 104 individuals convicted of sexual offending who applied for removal of notification requirements and were assigned to polygraph or comparison groups.