By PAUL FOYSALT LAKE CITY (AP) â¿¿ For years, Kennecott Utah Copper Corp. has been violating clean-air regulations at an open pit west of Salt Lake City by digging for more ore than allowed under a federally approved agreement and kicking up dust, clean-air groups argued Tuesday in federal court. It was the first time Kennecott has been hauled into court in Utah on a pollution complaint. U.S. District Judge Robert Shelby did not immediately make a ruling. Tuesday's arguments left him confused about whether Utah regulators or the U.S. Environmental Protection Agency had the authority to relax a limit on the amount of ore Kennecott can take from the Bingham Canyon Mine. "This gave me a great deal to think about," Shelby said Tuesday. "I'm your third judge in this case. I'll probably be the last." If they prevail with their lawsuit, Utah Moms for Clean Air and Utah Physicians for a Healthy Environment will seek sanctions and an order limiting production at the mine. By coincidence, Kennecott has been forced to scale back operations owing to an April landslide that damaged the ore pit, but it is trying to recover. It's also widening the pit to expand copper output, which prompted the citizen lawsuit. The groups say Kennecott is violating the U.S. Clean Air Act even though Utah's pollution regulators allowed the company to significantly ramp up mining production starting in 2006 by making up for the added dust with cuts in other emissions. According to the company, it has trimmed smelter, power plant and truck emissions with new technology. But it's the dust blowing around from the mining pit and a tailings pond that raises the biggest health concern, said Dr. Brian Moench, president of Utah Physicians for a Healthy Environment. He said the dust is as fine as talcum powder and contaminated with heavy metals.