A federal judge has disqualified the Keller Lenkner law firm from handling a lawsuit against Uber due to one of the firm’s lawyer’s work alongside the ride-hailing giant as the top appellate counsel at the U.S. Chamber of Commerce.

Warren Postman, who left the U.S. Chamber Litigation Center to join Keller Lenkner as a partner last summer, represented the Chamber as a co-plaintiff alongside Uber in a lawsuit challenging a Seattle ordinance that authorized independent contractor drivers to collectively bargain.