Electronic license plate readers (LPRs) are changing the nature of legal surveillance. For law enforcement, the scanners are a powerful tool for fighting crime — a highly effective "force multiplier," but a lack of regulation and the burgeoning market for privately-collected data has some judges and privacy activists concerned. Ars Technica takes a look at the explosive spread of LPRs, what happens to the data they collect, and the myriad new legal issues they present. As Lee Tien, a senior staff attorney at the EFF points out, LPR technology "forces us to really confront how many of the privacy norms that we form were implicitly dependent [on the fact] that the government couldn't afford to engage in mass, routine surveillance of the entire population."