Hill: Regulations at the center of President Obamas climate change initiative face a crucial test this week when opponents will attempt to block them before theyre even made final. A federal appeals court in Washington, D.C., will hear oral arguments Thursday in a high-stakes legal challenge to the Environmental Protection Agencys (EPA) proposed emissions limits for existing power plants. Murray Energy Corp., a major coal mining company, is asking the court to do something that it admits is extraordinary:...