Beyond ‘what works’: why systematisation matters and what more it can do for the criminal justice evidence base

That a convenience sample cannot safely be generalised from is a trite truism in research. Yet in the criminal justice field, unrepresentative samples of studies routinely inform policy, practice, and theory. Novel or familiar findings often carry disproportionate weight, and selective reading can generate unwarranted certainty about what we think we know. Systematic reviews offer a solution to this problem. By requiring transparent and reproducible methods, they constrain overinterpretation of partial evidence and can promote sound reasoning. Despite their centrality to evidence-based criminal justice, systematic reviews are often narrowly understood as tools for answering ‘what works’ questions. This paper argues that the same logic of systematisation can support a much broader range of knowledge needs, including theory development, mechanism and context synthesis, measurement refinement, and futures-oriented evidence mapping. Thus, systematic reviews are not simply a tool for judging intervention effectiveness, but a family of methods for building cumulative, policy-relevant knowledge.