If you own a cell phone, you’re carrying a miniature tracking device in your pocket — a fact law enforcement agencies are increasingly taking advantage of to investigate crimes and monitor suspected criminals. “Cell‐​site simulators” or “Stingrays” — first designed for military use, but increasingly in the hands of local police forces — are the technology that makes it possible. Yet those agencies have fought fiercely against efforts to inform the public about how they are used, and a recent bipartisan report by the House Committee on Oversight and Government Reform found there’s no consensus on the rules that should regulate their deployment, or even what legal authorities govern Stringray tracking. At this Cato Policy Forum, Rep. Jason Chaffetz will present his committee’s findings, followed by a panel discussion in which policy experts and technologists explore how law enforcement can exploit this powerful tool to fight crime — while also checking its enormous power to encroach on privacy.