Specifically, those challenging the EPA say it is reading too broadly its authority to regulate greenhouse gases, carrying over limits from vehicle transmissions and applying them to stationary sources such as power plants. They also say the EPA is picking and choosing which parts of the law to enforce by establishing a permitting scheme for greenhouse gas emitters, because its threshold for when those regulations take effect is above the law’s limits. The government argues a lower limit would potentially ensnare millions of buildings nationwide beyond the intent of the regulations, including public schools and some apartment buildings. It argues...