Evidence and liberty

Abstract

Evidence and liberty are two great ideas in British history. One consequence of both ideas is experimental criminology, which applies research designs developed in Britain to matters of liberty affecting the entire world. The promise of experimental criminology is to generate better evidence about how to increase liberty. The crucial challenge to experimental criminology is the means by which research results, even when accepted as true, may be translated into widespread practice. Two models for applying experimental research are possible. One is `bottom—up discretion', in which crime victims, police, judges and probation officers and others take experimental results into account when making their decisions one case at a time. Another model is `top—down guidance', in which either Ministers or an independent evidence-assessment agency like `NICE'—the National Institute of Health and Clinical Excellence—appoint committees of practitioners and researchers to develop succinct operational guidance based upon systematic reviews of experimental evidence. Bottom—up discretion will grow steadily from the sheer persistence of criminologists and practitioners doing experiments. Liberty could be advanced much faster by top—down guidance, however, if government chose to invest in `prospective meta-analysis' a method of multi-site randomized trials that would assess generalizability of policy effects as well as their magnitude and cost-effectiveness.