Abstract
Alley gates are designed to limit access to alleys and the crime opportunities they afford. Informed by the acronym EMMIE we sought to: 1) systematically review the evidence on whether alley gates are Effective at reducing crime, 2) identify the causal Mechanisms through which alley gates are expected to work and the conditions that Moderate effectiveness, and 3) collate information on the Implementation and Economic costs of alley gating. The results of our meta-analysis suggest that alley gating is associated with modest but significant reductions in burglary, with little evidence of spatial displacement. We also identified six mechanisms through which alley gates might plausibly reduce crime, and the conditions in which such mechanisms are most likely to be activated.