By Michelle Sydes, Lorelei Hine, Angela Higginson, James McEwan, Laura Dugan, Lorraine Mazerolle

Background: Criminal justice agencies are well positioned to help prevent the radicalisation of individuals and groups, stop those radicalised from engaging in violence, and reduce the likelihood of terrorist attacks. This Evidence and Gap Map

(EGM) presents the existing evidence and gaps in the evaluation research. Objectives: To identify the existing evidence that considers the effectiveness of criminal justice interventions in preventing radicalisation, violent extremism and terrorism.

Search Methods: We conducted a comprehensive search of the academic and grey literature to locate relevant studies for the EGM. Our search locations included the Global Policing Database (GPD), eight electronic platforms encompassing over 20 academic databases, five trial registries and over 30 government and nongovernment websites. The systematic search was carried out between 8 June 2022 and 1 August 2022.

Selection Criteria: We captured criminal justice interventions published between January 2002 and December 2021 that aimed to prevent radicalisation, violent extremism, and/or terrorism. Criminal justice agencies were broadly defined to include police, courts, and corrections (both custodial and community). Eligible populations included criminal justice practitioners, places, communities or family members, victims, or individuals/groups who are radicalised or at risk of becoming radicalised. Our map includes systematic reviews, randomised controlled trials, and strong quasi‐experimental studies. We placed no limits on study outcomes, language, or geographic location.

Data Collection and Analysis: Our screening approach differed slightly for the different sources, but all documents were assessed in the systematic review software program DistillerSR on the same final eligibility criteria. Once included, we extracted information from studies using a standardised form that allowed us to collect key data for our EGM. Eligible systematic reviews were assessed for risk of bias using the AMSTAR 2 critical appraisal tool.

United States, Campbell Collaboration. 2023, 53pg

By Jonathan Kenyon

The overarching aim of this doctoral research was to investigate the role of the Internet in radicalisation pathways and offending of convicted extremists in England and Wales. The empirical study was unique because it benefitted from access to closed source risk assessment reports within His Majesty’s Prison and Probation Service (HMPPS). These reports were authored by Psychologists and Probation Officers with access to restricted case documentation and in the majority of cases, direct interviews with the individuals concerned. Findings were based on 235 convicted extremists, all of whom were considered to have radicalised prior to committing their offence. Variables of interest, including offender demographics, offence characteristics and online activities were extracted from risk reports completed from October 2010 to December 2017. Since completion of the doctorate, the analysis has been expanded to 437 convicted extremists, which includes all those subject to risk reports from October 2010 to December 2021. This accounts for close to every convicted extremist in England and Wales considered to have radicalised prior to their conviction.

Scotland: Centre for Research and Evidence on Security Threats, 2023, 4p.