The Impacts of Large-Scale License Plate Reader Deployment on Criminal Investigations

The use of automated license plate readers (LPRs) has spread rapidly among American police in recent decades. However, research on LPRs has been very limited and focused primarily on small-scale use of LPRs in patrol. This study expands the evidence base on LPRs by evaluating investigative use of a large-scale fixed LPR network in one populous city. Survival analysis methods were used to assess changes in the likelihood and timing of investigative case closures in this city following installation of a fixed network of nearly 100 LPRs. The analysis focused on auto theft, theft of vehicle parts, and robbery investigations, which account for most uses of LPRs by investigators. Case clearances for auto theft and robbery improved after the installation of the LPR network, particularly in places where LPRs were concentrated. However, these changes were not statistically significant in multivariate analyses, and patterns in the data suggest that other factors may have also contributed to higher clearances during the intervention period, particularly for auto theft cases. Results suggest that large-scale LPR deployment may have the potential to improve investigative outcomes for some serious crimes-particularly with more consistent use and better placement for investigations-but further assessment is needed. More generally, additional research is needed to determine the best uses of LPRs, the optimal scales and methods of LPR deployment, and the full range of costs and benefits associated with LPR use.