The online taxi company Uber is getting a rough handling from the US courts. Uber Chief Executive Travis Kalanick has been told that he disclose some of his emails to plaintiff lawyers in a lawsuit accusing the car service of misleading customers about how it shares gratuities with drivers.

An Uber customer filed a proposed class action lawsuit against the company earlier this year, saying an advertised 20 percent gratuity is "false, misleading, and likely to deceive members of the public" because Uber keeps a substantial portion of the money. Plaintiff attorneys argued that Kalanick and other executives should disclose emails that contain evidence about Uber's tipping practices.

The company said that would be overly burdensome because such policies are set by the general manager in each city, which operate as their own "individual business," according to a court filing. However US Magistrate Judge Donna Ryu said Uber is a new startup with relatively few employees and it should not be difficult. Driver gratuities is an issue that Kalanick and other top executives "are likely to be involved in," Ryu said.

Uber's business practices have come under scrutiny, with some customers alleging privacy violations. Earlier this month a senior Uber executive caused an uproar when he told journalists that Uber should consider hiring researchers to examine and disclose activities of media critics.