The deal between Uber and drivers in California and Massachusetts did not compensate drivers enough, the judge ruled.
The April settlement was three years in the making. Its rejection could force Uber to dig deeper to reach a deal.
The lawsuits had charged that the drivers should be treated as employees, rather than independent contractors. That would have entitled the drivers to a variety of benefits, including overtime and health insurance. It also might have put Uber on the hook for some of the drivers expenses, such as gas and tolls.