The Greyball software employs a dozen data points on a new user in a given market, including whether a rider’s Uber app is opened repeatedly in or around municipal offices, which credit card is linked to the account, and any publicly available information about the new user on social media. If the data suggests the new user is a regulator in a market where Uber is not permitted, the company would present that user with false information about where Uber rides are. This includes showing ghost cars or no cars in the area.

The city concluded that, when Uber started operating in the city in December 2014 without Portland’s authorization, the Greyball tool blocked 17 rider accounts. Sixteen of those were government employees. In all, Greyball denied 29 ride requests by city transportation enforcement officers.

“In using Greyball, Uber has sullied its own reputation,” the Portland Bureau of Transportation said.

Greyball is just one of myriad scandals confronting Uber. There are too many for a comprehensive list here, but one scandal concerns whether Uber stole trade secrets for a self-driving vehicle venture. Another centers around whether the company used software to defraud both drivers and riders out of money.