The U.S. Court of Appeals for the District of Columbia Circuit questioned industry groups during oral argument April 17 to explain how they were harmed by Environmental Protection Agency waivers allowing gasoline to contain up to 15 percent ethanol, and whether they had standing to bring the challenges. Several industry groups representing petroleum producers and suppliers, engine and automobile manufacturers, and food producers petitioned the court to overturn the waivers, which the agency partially granted under the Clean Air Act, allowing E15 to be used in model year 2001 and newer vehicles in response to requests from ethanol producers.