The U.S. Court of Appeals for the 10th Circuit will hear oral arguments Jan. 21 in a case that could pose a crucial test for whether state renewable energy mandates are constitutional, and could also have a significant impact on states' ability to use their mandates to comply with EPA's greenhouse gas (GHG) rule for existing power plants. The Denver-based court will hear arguments in the case, Energy & Environmental Legal Institute (EELI), et al., v. Joshua Epel, et...