FILE - In this April 4, 2013 file photo, a mechanized shovel loads coal onto a haul truck at the Cloud Peak Energy's Spring Creek mine near Decker, Mont. Montana tax authorities argue Tuesday, Nov. 25, 2014, before the state Supreme Court that a Wyoming mining company owes $3.4 million for selling coal to an affiliate at less than market value. At issue is whether coal should be valued for tax purposes at the time the fuel is mined and shipped or when a sale is negotiated. (AP Photo/Matthew Brown, File)