By Michelle Sydes | Lorelei Hine | Angela Higginson4 | James McEwan | Laura Dugan | Lorraine Mazerolle3

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 non‐ government 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. Main Results: The systematic search identified 63,763 unique records. After screening, there were 70 studies eligible for the EGM (from 71 documents), of which two were systematic reviews (assessed as moderate quality), 16 were randomised controlled trials, and 52 were strong quasi‐experimental studies. The majority of studies (n = 58) reported on policing interventions. Limited evidence was found related to courts or corrections interventions. The impact of these interventions was measured by a wide variety of outcomes (n = 50). These measures were thematically grouped under nine broad categories including (1) terrorism, (2) extremism or radicalisation, (3) non‐terror related crime and recidivism, (4) citizen perceptions/intentions toward the criminal justice system and government, (5) psychosocial, (6) criminal justice practitioner behaviours/attitudes/ beliefs, (7) racially targeted criminal justice practices, (8) investigation efficacy, and (9) organisational factors. The most commonly assessed outcomes included measures of terrorism, investigation efficacy, and organisational factors. Very limited research assessed intervention effectiveness against measures of extremism and/or radicalisation. Authors’ Conclusions: Conducting high‐quality evaluation research on rare and hidden problems presents a challenge for criminal justice research. The map reveals a number of significant gaps in studies evaluating criminal justice responses to terrorism and radicalisation. We conclude that future research should focus attention on studies that consolidate sound measurement of terrorism‐related outcomes to better capture the potential benefits and harms of counter‐terrorism programs, policies and practices which involve criminal justice agencies.

Campbell Systematic Reviews, 19(4). 2023. 53p.

By Michael Wolfowicz, Yael Litmanovitz, David Weisburd, and Badi Hasisi

Abstract Background: Two of the most central questions in radicalization research are, (1)why do some individuals radicalize when most of those from the same groups or exposed to similar conditions do not? and (2) why do radicalized individuals turn to radical violence while the majority remain inert? It has been suggested that the answer to both questions lie in the cumulative and interactive effects of a range of risk factors. While risk assessment and counter‐radicalization take a risk‐protectivefactor approach, there is widespread debate as to what these factors are and which are most important.Objectives: This review has two primary objectives.1) To identify what the putative risk and protective factors for different radica-lization outcomes are, without any predeterminations.2) To synthesize the evidence and identify the relative magnitude of the effects of different factors.The review's secondary objectives are to:1) Identify consistencies in the estimates of factors across different radicalizationoutcomes.2) Identify whether any significant heterogeneity exists within factors between(a) geographic regions, and (b) strains of radicalizing ideologies.Search Methods: Over 20 databases were searched for both published and gray literature. In order to provide a more comprehensive review, supplementary sear-ches were conducted in two German and one Dutch database. Reference harvesting was conducted from previous reviews and contact was made with leading researchers to identify and acquire missing or unpublished studies.Selection Criteria: The review included observational studies assessing the out-comes of radical attitudes, intentions, and/or radical behaviors in OECD countries and which provided sufficient data to calculate effect sizes for individual‐level risk and protective factors.Data Collection and Analysis: One‐hundred and twenty‐seven studies, containing 206 samples met the inclusion criteria and provided 1302 effect sizes pertaining to over 100 different factors. Random effects meta‐analyses were carried out for each factor, and meta‐regression and moderator analysis were used to explore differ-ences across studies.Results: Studies were primarily cross‐sectional, with samples representing 20 OECD countries. Most studies examined no specific radicalizing ideology, while others focussed on specific ideologies (e.g., Islamist, right‐wing, and left‐wing ideologies). The studies generally demonstrated low risk of bias and utilized validated or widely acceptable measures for both indicators and outcomes.With some exceptions, sociodemographic factors tend to have the smallest estimates, with larger estimates for experiential and attitudinal factors, followed by traditional criminogenic and psychological factors.Authors' Conclusions: While sociodemographic factors are the most commonly examined factors (selective availability), they also tend to have the smallest es-timates. So too, attitudinal and even experiential factors, do not have effect sizes of the magnitude that could lead to significant reductions in risk through tar-geting by interventions. Conversely, traditional criminogenic factors, as well as psychological factors tend to display the largest estimates. These findings suggest the need to broaden the scope of factors considered in both risk assessment and intervention, and this review provides much needed evidence for guiding the selection of factors

Campbell Systematic Reviews: Volume 17, Issue 3 September 2021, 90 p.