Tuesday evening, the U.S. Supreme Court granted a stay, halting implementation of the Environmental Protection Agency’s Clean Power Plan pending the resolution of legal challenges to the program in court. The CPP is arguably the Obama administration’s signature environmental initiative, representing the EPA’s most ambitious effort to control greenhouse gas emissions under the Clean Air Act. Five separate stay applications were filed by more than two dozen states and numerous industry groups. Other states, environmental groups and some energy companies opposed the stay.