John Brady, the director of communications at the Portland Bureau of Transportation, said they uncovered these drivers after they started doing a system of "random checks."
"For 80 people a month, we do the full background check, we do criminal history and if the person is on the sex offender list," he told ABC News. They also do a series of random field checks using "secret shoppers and uniformed personnel" who check the safety of the vehicles and more.
While two of the 168 drivers were felons, "you can be disqualified for driving for a number of things, if you haven’t had a driver's license continuously for the past year, if you have had a certain number of traffic violations, if you have been involved in any traffic crime, if you don't have a valid license, it runs the gamut," Brady added.
"We have tens of thousands of taxi, Uber and Lyft drivers and by and large, they are safe drivers and safe individuals but we’re committed to finding anyone who isn't and make sure that they aren’t driving," Brady said.
A spokesperson for Uber told ABC News, "There's nothing more important than the safety of the drivers and riders we serve. We have strengthened our background checks and introduced new screening technology that monitors new criminal offenses. But safety does not start and end with a background check."
"Uber has a number of safety features in place for riders and drivers, including an emergency button with 911 integration technology in more than 250 cities across the US, including Portland. We will continue to put safety at the heart of our business,” the statement added.
Lyft told ABC News that "safety is fundamental" to them and "since the beginning we have built products and policies with that in mind."
The statement continued: "All those who apply to drive with Lyft are screened for criminal offenses and driving incidents. Lyft was the first rideshare company to institute criminal background checks. Just this summer we announced an expansion of our criminal background check process to include continuous monitoring, as well as a new enhanced identity verification process. Any driver who does not pass the initial, annual, and continuous screenings is not able to use our platform. We are constantly working to improve the safety of our platform and are committed to delivering the best experience for all users."