Sen. Al Franken has a pattern of calling on car-hailing services Uber and Lyft, and not because the Minnesota Democrat needs a ride.

Franken has sent letters to the chief executives of both companies over the past two years that question their policies and practices when it comes to protecting customers from privacy infringement and discrimination. The latter issue was the subject of a Nov. 2 missive in which Franken voiced concern after an independent study found black riders in two cities faced longer wait times and higher ride-cancellation rates.

On Wednesday, the senator’s office released the responses it received from both companies, responses that largely focused on efforts already in place to mitigate discrimination. The letters from Uber and Lyft, dated Nov. 30 and Dec. 16, respectively, said the companies would continue to look for ways to reduce discrimination while also releasing enough identifying information to establish trust and transparency between the driver and passenger.

The National Bureau of Economic Research released a study in October that analyzed 1,500 rides taken through several ride-hailing platforms in Boston and Seattle. It found that riders thought to be black waited as much as 35 percent longer to be picked up, and were twice as likely to have their ride canceled by the driver. The report concluded that seeing passengers’ photos and names may contribute to drivers’ ability to discriminate based on race and gender.

Franken sent a letter to the chief executives of both companies on Nov. 2 asking them to outline policies in place to prevent race and gender discrimination, and questioning the feasibility of removing passenger photos and names from the ride-hailing apps if it would mean less discrimination.

Uber and Lyft maintain that discrimination cannot be eliminated, though both have taken steps to mitigate it. Uber only shows the passenger’s first name to drivers, not their family name or photo. Lyft, however, provides its drivers with the name and photo of passengers before they accept the ride.

The companies also touted ride-hailing services as expanding affordable transportation into neighborhoods that were previously underserved by public transit or taxicab companies.

Franken, who is the ranking Democrat on the Senate’s Judiciary Subcommittee on Privacy, Technology and the Law, has a history of challenging the companies on policies he sees as unfavorable to consumers. In late 2014, Franken sent letters to the chief executives of Uber and Lyft asking the companies to explain when their employees access users’ ride information and how the company discloses that to consumers.

Last week, Franken again took aim at Uber after the company altered its privacy settings so that the company can track riders’ movement for several minutes after their ride concludes. Uber also removed the option that allowed customers to choose when the app collects information about their location.

Uber, Lyft and Franken’s office did not respond to requests for a comment.

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