On April 4, 2011, American Tradition Institute, American Tradition Partnership and plaintiff Rod Lueck sued the State of Colorado and several officials over the constitutionality of the state's Renewable Energy Standard mandate. The RES requires the state's major utilities (mainly Xcel Energy) to obtain 30 percent of their power generation from "renewable" sources by the year 2020.
ATI claims that the Colorado RES discriminates on its face against legal, safer, less costly, less polluting and more reliable in-state and out-of-state generators of electricity sold in interstate commerce. This discrimination is forbidden by the Commerce Clause, which reserves the regulation of interstate commerce to the federal government.