Uber has admitted it used a tool to thwart city regulators, and announced a review of its controversial Greyball technology. From a report on USA Today: Greyballing, a play on blackballing, was a way for Uber officials to remotely provide ghost driver information to a targeted individual. A March 3 report on the program in The New York Times cited a 2014 example where a regulator in Portland, Ore., a city in which Uber was operating without approval at the time, was unable to hail a car because of his Greyball-powered app. "We have started a review of the different ways this technology has been used to date," Joe Sullivan, Uber's chief security officer, wrote in a blog post. "In addition, we are expressly prohibiting its use to target action by local regulators going forward."